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Economic aspects of alternatives to methyl bromide in the postharvest and quarantine treatment of selected fresh fruits
Crop Protection 19 (2000) 161}168
Economic aspects of alternatives to methyl bromide in the postharvest and quarantine treatment of selected fresh fruits Anthoni F. Aegerter, Raymond J. Folwell* Department of Agricultural Economics, Washington State University, PO Box 646210, Pullman, WA 99164-6210, USA Received 2 April 1999; received in revised form 20 September 1999; accepted 21 September 1999
Abstract Methyl bromide is the most commonly used postharvest and quarantine treatment of temperate fruit worldwide. Low costs, short fumigation times, and consistent quarantine security are the main reasons for methyl bromide's dominance. Recent environmental issues and laws have created the need for an alternative to methyl bromide for postharvest and quarantine treatment of fresh fruits. The objective of this study was to analyze alternative treatment scenarios with capabilities equal to those achieved by methyl bromide for treatment of apples, sweet cherries, nectarines, peaches, and plums. Partial budget scenarios for each commodity were developed to determine the methyl bromide treatment costs which established a benchmark scenario to compare to the alternative treatment scenarios of each commodity. Irradiation was the only alternative identi"ed that was available for all the fruits in this study. Cost increases for all fruit treated with irradiation ranged from two to 14 times methyl bromide costs. Controlled atmosphere storage for apples had cost increases of 122% over methyl bromide costs. Costs for regular cold storage for apples was 93% of the benchmark cost. However, the reduced costs of suppressing the pests resulted in a marketing window of only four months since there is an eight-month limit on regular cold storage and four months were required for suppressing the pests. 2000 Elsevier Science Ltd. All rights reserved. Keywords: Methyl bromide; Fumigation; Costs
1. Introduction Annually, 15}40% of the world's food supply is destroyed before consumption (USDA, 1993b). Insects are a signi"cant contributor to this food destruction. Pests infesting fresh fruits before and after harvest can render commodities unmarketable. Postharvest and quarantine treatments are used to disinfest commodities from insects after harvest and to provide quarantine security. Quarantine security can be de"ned as the degree of statistical probability needed by treatments to disinfest host commodities so that upon transport of the treated products, the targeted pests cannot become established in any area where they do not already exist. The current measure of quarantine security accepted by the United States (US) and most of its trading partners is the concept of probit9. Probit-9 requires mortality of 99.9968% or no more
* Corresponding author. Tel.: #1-509-335-5556; fax: #1-509-3351173. E-mail address: [email protected] (R.J. Folwell).
than three survivors per 100,000 treated pests. Failure of quarantine treatments may result in expensive eradication procedures, product losses due to infestation, loss of markets, and costly new quarantine treatments (Paull and Armstrong, 1994). In the recent rapid expansion of world trade, any disruption of trade can potentially be costly to all parties involved. Methyl bromide is the most commonly used treatment that consistently meets probit-9 speci"cations. The fumigant is a broad spectrum pesticide used in a wide variety of commodities. In recent years, annual US consumption of methyl bromide has been approximately 30,000 ton which accounts for 41% of the world's use (US Environmental Protection Agency, 1995). Soil fumigation to sterilize soil in preplant preparation of the soil for crop planting accounts for 85% of US consumption. Postharvest and quarantine treatments of fruits, nuts, vegetables, and grains account for the remaining 15% (USDA, 1993b). Methyl bromide is the most widely used fumigant for postharvest and quarantine treatments of agricultural commodities and is the only accepted treatment for temperate fruit worldwide that meets
0261-2194/00/$ - see front matter 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 2 6 1 - 2 1 9 4 ( 9 9 ) 0 0 0 8 1 - 2
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international phytosanitary requirements for freedom from insect infestations (California Department of Food and Agriculture, 1996). However, there are some major concerns in the applications of methyl bromide. It is an extremely dangerous and deadly fumigant, and special care is needed for those people that are conducting the applications. Scienti"c studies have linked methyl bromide to ozone depletion which have raised questions regarding the continued use of the fumigant. Under the Montreal Protocol, methyl bromide was initially to be phased out in the US under the US Clean Air Act by January 1, 2001. The 1999 federal budget made the US phase out identical to that required by the Montreal Protocol for developed countries and allowed for the same exemption. The schedule for phase out in developed countries and the Montreal Protocol is: (1) 25% reduction in 1999; (2) 25% reduction in 2001; (3) 20% reduction in 2003; (4) and a complete phase out in 2005. Exemptions include quarantine, critical uses, and certain preshipment uses. Numerous problems in postharvest and quarantine treatments will arise with the eventual loss of methyl bromide. Farmers in developed countries such as the US will be at a competitive disadvantage when competing with products produced in developing countries where methyl bromide will be available for several years after it is phased out in the US. There will be increased competition from countries not banning methyl bromide. The loss of methyl bromide could create potential trade barriers for the US in both the domestic and foreign export markets. Without methyl bromide or an acceptable alternative, the US will not be able to export to these markets. Alternative postharvest and quarantine treatments must be as e!ective as methyl bromide and be able to meet environmental and regulatory requirements. Alternatives should be able to combat the abilities of pests to develop resistances to treatments through rapid reproduction rates and short lifecycles. Treatments need to be developed to eradicate all life stages of insects that may be found on the product exported with equal success. The characteristics of the host commodity, especially tolerance to treatments, should also be considered when implementing alternative treatments. The timeliness or the time needed to carry out the content of each alternative treatment is another important consideration. The treatment time must not signi"cantly reduce the time available to market a product within its useful life. The downward pressure on prices from marketing the commodity in a shorter window of opportunity could be an economic disaster. This study considered gamma irradiation, regular cold storage, and controlled atmosphere storage as potential commercially available alternatives to methyl bromide in postharvest and quarantine treatments of selected fresh fruits. Other available alternative treatments that were
Table 1 Postharvest and quarantine pests of economic importance Tree variety
Common name
Scienti"c name
Apples
Codling moth Mediterranean fruit #y Oriental fruit #y San Jose scale Apple maggot
Cydia pomonella Ceratitis capitata Dacus dorsalis Aspidiotus perniciosus Rhagoletis pomonella
Cherries
Codling moth Mediterranean fruit #y Oriental fruit #y Cherry fruit #y
Cydia pomonella Ceratitis capitata Dacus dorsalis Rhagoletis cingulata
Nectarines/ Peaches/Plums
Peach twig borer Codling moth Oriental fruit moth Walnut husk #y Plum Curculio Mediterranean fruit #y
Anarsia lineatella Cydia pomonella Grapholitha molesta Rhagoletis completa Conotrachelus nenuphar Ceratitis capitata
Adapted from: Paull and Armstrong, 1994.
not analyzed included electron beam irradiation, phosphine fumigation, heat treatments, and the systems approach. Electron beam irradiation was not a viable alternative due its low degree of penetration and lack of commercial applications in high volume packing operations. Phosphine can only be used on tree nuts or dried fruit due to its detrimental e!ects on fresh fruits. With some exceptions the available heat treatments have been shown to be e!ective against temperate insects. However, possible damage to the #esh of some fresh fruits may compromise the fruit quality. Presently, the only commercial heat treatment applications are for the disinfestation of tropical fruits. The systems approach which combines cultural practices with other activities to suppress the insect populations is presently under development, and costs are unquanti"able due to the broad scope of varying activities and lack of total implementation. The postharvest and quarantine treatments of apples, cherries, plums, nectarines, and peaches, along with the insect pests commonly associated with these commodities are presented in Table 1. This study consists of an economic analysis of potential, commercially available alternatives, for the postharvest and quarantine treatment of apples, cherries, nectarines, peaches, and plums. The alternatives need capabilities equal or similar to those achieved by methyl bromide in terms of time required and pest mortality. Public, legal, and regulatory acceptance, as well as environmental impacts and safety factors, will also have to be addressed before any techniques are accepted. The goal of this study was to make comparisons between alternatives on an economic basis.
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2. Methodology 2.1. Budgeting techniques, assumptions, and alternative treatments Methyl bromide fumigation costs for each commodity were estimated to establish a benchmark scenario to compare alternative treatment scenarios. Treatment scenarios were developed on a commercial scale for the technically feasible alternatives, and costs were determined using current industry practices. Several assumptions were made to facilitate comparability among scenarios. Methyl bromide was assumed to be unconditionally banned. Therefore, methyl bromide recycling scenarios were not considered. Each scenario represented a single step in the marketing channel, and costs were estimated utilizing economic engineering techniques. The speci"cations for the buildings and equipment are discussed for each scenario since they were di!erent for some of the fruits. Rather than developing multiple quantity scenarios for each commodity, the chosen scenario for each commodity represents an average quantity or most commonly occurring quantity situation. Building and equipment costs were adjusted to 1995 dollars using a price index for private "xed investment (US Department of Commerce, Bureau of Economic Analysis, 1996). All buildings were straight-line depreciated over 15 years with no salvage value, and all machinery was straight-line depreciated over ten years with no salvage value. The depreciation schedules are industry accepted and promote conservative cost estimates. Apples were considered a storable commodity whereas cherries, plums, peaches, and nectarines were assumed to be packed and shipped immediately after harvest due to their high perishability. 2.2. Methyl bromide fumigation (benchmark) Methyl bromide fumigation is an advantageous procedure for processors in the postharvest and quarantine treatment of fruits. The injection process and the stabilization of concentrations usually take 30 min. Most fumigation treatments can be accomplished in 2}24 h of exposure. A fumigation chamber can be any airtight enclosure from a tarp-covered structure to a cement building. Perishable commodities can take 24}36 h to move from orchard to market using methyl bromide fumigation (Schreiber, 1996). The product is immediately susceptible to reinfestation with methyl bromide fumigation as well as the alternatives discussed here. Methyl bromide fumigation of apples is currently a rare occurrence. Japan and Korea are the only countries currently demanding probit-9 security for codling moth in apples. Their combined imports amount to less than 2% of total US apple exports. Shipments of apples to these countries are relatively small and spread out over
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the marketing year resulting in small applications of methyl bromide. It was assumed that the apples treated with methyl bromide were handled by one "rm since the small quantity has a tendency to distort fumigation costs by spreading large "xed costs over a small tonnage of apples. This assumption allowed for a more realistic evaluation of costs. In the methyl bromide scenario for apples, a 1699 cm fumigation chamber and a 6118 m regular cold storage unit were utilized. The chamber had the capacity to fumigate 725 "eld bins per treatment, and the cold storage unit accommodated 27,000 "eld bins with 397 k per "eld bin in two rooms of equal size. For simplicity, cold storage apples were assumed to be unloaded and packed starting in the "rst month of storage. However, apples destined for Japan and Korea were assumed held for at least 55 days in cold storage at 2.23C. Therefore apples that are ready for marketing before their time requirement would be shipped to other markets and then the fruit removed from storage after the time requirements could be shipped to Japan and Korea. Apples have a shelf life of eight months in regular cold storage, and it was assumed that the apples were unloaded at a constant rate over the eight months. At this rate, 3375 "eld bins could be fumigated and packed per month. With a 725bin capacity chamber, a fumigation occurred every six days. The fumigation chamber was "lled with bins from the cold storage unit, and the methyl bromide was applied and ventilated in a 24-h period. The chamber was then unloaded as the apples were packed and shipped over a "ve-day period before the next fumigation. At the end of month four, the "rst room in the cold storage unit was empty, and its refrigeration unit was shut down. The second room was opened and emptied by the end of month eight. Fumigating fresh sweet cherries for codling moth and other insects with methyl bromide is a standard routine in postharvest operations. Since fresh cherries are an extremely perishable commodity, methyl bromide o!ers a quick and easy insecticidal treatment for both export and domestic use. Japan, South Korea, Mexico, Egypt, Peru, Pakistan, and British Columbia, along with several US states all require methyl bromide fumigation of fresh cherries. For this study, it was assumed that cherries were harvested over a three-week period and shipped immediately after harvest due to the high perishability of the fruit. In the methyl bromide sweet cherry scenario, a 1699 cm fumigation chamber was located adjacent to the packing house. The chamber had the capacity of handling 1370 "eld bins per treatment. As the cherries were brought in from the orchards, the chamber was "lled with "eld bins. The cherries were hydro-cooled in the chamber in preparation for the methyl bromide application. Once applied, the methyl bromide was allowed to disinfest the cherries overnight, and the chamber was
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ventilated the next morning. The cherries were then unloaded, packed, and prepared for shipment. After the chamber was emptied, the process was repeated with the fresh cherries picked that day. Soft fruits (nectarines, peaches, and plums) are fumigated with methyl bromide as a quarantine treatment but not with the same regularity as sweet cherries. The only soft fruit fumigated are those sent to the states or countries demanding quarantine security. Japan and South Korea require methyl bromide fumigation of the soft fruits to ensure quarantine security from codling moth. Mexico, Egypt, Pakistan, Peru, British Columbia, California, Texas, Florida, and Arizona, require quarantine treatments against fruit #ies in the soft fruits. In this study, it was assumed that all soft fruits were to be fumigated before shipment to either export or domestic markets and that the total harvest period for the three fruits covered three and a half months. Packing houses were assumed to pack nectarines, peaches, and plums on individual packing lines throughout this harvest period. Once packed, all three fruit varieties were placed in the chamber as they came o! the packing line and then fumigated. Nectarines are usually harvested from mid June through late August, peaches are harvested from early June to late September, and plums are picked from late May through late September. For the soft fruit methyl bromide scenario, an 849.5 cm fumigation chamber with no refrigeration unit was located adjacent to the packing house. Soft fruit does not require refrigeration for fumigation purposes so the chamber was not out"tted with a refrigeration unit. The chamber had the capacity to fumigate 7810 boxes of packed fruit per treatment. Soft fruits are susceptible to bruising, and extra care in handling is required to minimize blemishes. Packing houses normally sort and pack soft fruit before fumigating them to minimize bruising. After the fruit was packed, it was placed in the chamber and fumigated. Treatment times lasted less than 12 h including time for loading and unloading the packed commodities. This allowed for the use of a smaller chamber, two fumigations per 24 h period, and better timing logistics in shipping the commodity to its "nal destination. 2.3. Irradiation (alternative) The irradiation process involves the use of ionizing radiation to control insects infesting the commodity at a single point in the commodity's transit. Irradiation sources can be either gamma particles, usually from cobalt60, or electron beam particles formed from electron beam accelerators. Irradiation processes are not temperature dependent, can treat sealed containers, and leave no residues (USDA, 1993a). Irradiation has been proven to lengthen the shelf life and/or delay ripening in several food commodities. Irradiation does not cause a high,
immediate mortality rate but rather sterilizes most insects. This will require quarantine o$cials to accept products and commodities infested with live, though sterile, adult insects or live immature insects incapable of reaching the adult stage. The lack of residuals makes the commodities susceptible to reinfestation as is the case with methyl bromide. This procedure is complicated by the fact that fruits can only be irradiated once according to regulatory rules. E!ectiveness of this treatment is commodity speci"c in regards to the level of tolerable exposure. Two scenarios were developed for the irradiation of apples. One scenario assumed that the apple packer owned the gamma irradiation facility whereas in the second scenario the packer shipped boxed apples to a port owned facility to be irradiated and then shipped the apples to their "nal destinations. A 2415.5 m irradiation facility and a 6118.0 m cold storage unit with two rooms of equal size were used in the packer owned irradiation scenario. For simplicity in this study, cold storage apples were assumed to be unloaded and packed starting in the "rst month of storage. Apples have a shelf life of eight months in regular cold storage, and it was assumed that the apples were unloaded at a constant rate over the eight months. At this rate, 3375 "eld bins could be irradiated and packed per month. Three trucks of apples, approximately 18 t per truck, can easily be irradiated in a day to meet this unloading rate. For this scenario, it was assumed that the irradiation was only used for apples and was shut down after all the apples were treated. In the port owned irradiation scenario for apples, the packer owned a 6118.0 m regular cold storage facility. The facility had the capacity to hold 27,000 apple "eld bins in two rooms of equal size. For simplicity in this study, cold storage apples were unloaded and packed starting in the "rst month of storage. Apples with a shelf life of eight months in regular cold storage, and it was assumed that the apples were unloaded at a constant rate over the eight months. At this rate, 3375 bins could be packed and irradiated per month. Unlike the packer owned irradiation scenario, the packer unloaded the "eld bins and boxed the apples before trucking them to be irradiated and then delivered to their "nal destinations. This prevented shipping the irradiated apples back to the packer to be boxed and shipped to their "nal destinations. The only feasible alternative treatment for cherries was gamma irradiation. Fresh cherries cannot be held in regular cold storage or controlled atmosphere storage long enough to meet quarantine requirements. For the sweet cherry scenario, it was assumed that the packer would irradiate cherries at a port owned facility because it is cost prohibitive to build an irradiation that would be used only for the three weeks during harvest. The cherries were hauled from the orchards in "eld bins and trucked
A.F. Aegerter, R.J. Folwell / Crop Protection 19 (2000) 161}168
to the packing shed to be sorted and boxed. After packing, the cherries were trucked to a port owned irradiation facility for treatment before "nal shipment. The only feasible alternative treatment for nectarines, peaches, and plums was gamma irradiation. Nectarines, peaches, and plums cannot be held in regular cold storage or controlled atmosphere storage long enough to meet quarantine requirements. One scenario assumed that the soft fruit packer owned the irradiation facility whereas in the second scenario the packer shipped boxed fruit to a port owned facility to be irradiated. A 2415.5 m irradiation facility neighboring a packing shed was used in the processor/packer owned irradiation scenario. The soft fruits arrived at the packing shed from the orchards where they were sorted and boxed. The boxed fruits were then conveyed from the packing shed through the irradiation. In the port owned irradiation scenario, the soft fruits were trucked to the packing shed from the orchards. At the packing shed, the fruits were sorted and boxed. The boxed fruit was then trucked to the port owned irradiation facility and treated. Once treated, the fruits were transported to their "nal destinations. 2.4. Controlled atmosphere cold storage (alternative) Controlled atmosphere cold storage (CA) is a process of modifying the air in a refrigerated enclosure to su!ocate insects by purging or displacement of oxygen. The resulting atmosphere has a low oxygen/high carbon dioxide or high nitrogen concentration. CA storage promotes a longer storage life for commodities than regular cold storage. The treatment has proven its e$cacy, leaves no residues, and is environmentally safe. However, this treatment alternative has high capital costs, is temperature dependent, and is slow acting. The commodity is also susceptible to immediate reinfestation after removal from storage as with the other alternatives considered. Commodity treatment is limited to the space available and requires well-sealed chambers. CA is also commodity speci"c based on perishability. Apples in controlled atmosphere cold storage must be held for 90 days at 0}1.673C and in an atmosphere with less than 2% oxygen and less than 3% carbon dioxide. In these conditions, pests of all stages are successfully eradicated (Drake, 1996). In the controlled atmosphere storage scenario, a 5258.3 sm controlled atmosphere cold storage facility was used as the treatment facility. The facility had a total volume of 49,667.7 cm, could hold 27,000 apple "eld bins, and had eight rooms of equal size. As each room was "lled, the doors were sealed, and the oxygen was drawn down. The draw down took approximately 24 h per room to complete. To meet probit-9 speci"cations, the apples were held for 90 days after the purging was complete. Apples have a shelf life of 11 months in controlled atmosphere cold storage. It was
165
assumed that the apples were held in storage for the "rst three months (90 days) and then unloaded at a constant rate over the next eight months. At this rate, 3375 bins were packed and shipped each month. 2.5. Regular cold storage (alternative) Regular cold storage is the refrigeration of commodities at temperatures that e!ectively kill pests. Most fresh commodities are held at 0.0}1.103C without any change in atmospheric gases. Cold storage is a simple procedure, leaves no residues, and is environmentally safe. Drawbacks include that it is a slow process and is limited to the storage space available and to the storage life of the commodity. The treatment process is commodity speci"c in terms of e!ectiveness and is often used in combination with other treatments to meet probit-9 speci"cations and time constraints. Potential apple alternative treatment scenarios included gamma irradiation, stand alone regular cold storage, and controlled atmosphere cold storage. Regular cold storage as a stand alone treatment requires that the apples in the storage facility be held for 120 days at temperatures ranging from 0}1.103C to meet probit-9 speci"cations. This temperature range is e!ective for eradicating insects in the non-diapausing stages and the egg stage. Insects in the diapausing stage can withstand the extreme temperatures and may survive the storage temperatures. In apples, diapausing stages are not usually found in the stored fruit so the cold storage treatment can be used as an e!ective means of reaching probit-9 levels (Mo$tt, 1996). The regular cold storage scenario for apples utilized a 6118 m cold storage unit as the lone treatment apparatus. The cold storage facility had the capacity to accommodate 27,000 apple "eld bins in two equal size rooms. Once loaded, the doors of the storage unit were sealed for 120 days. Apples have a shelf life of eight months in regular cold storage so the apples had to be unloaded within four months of the "nished treatment time. In this scenario, it was assumed that apples would be unloaded at a constant rate over the four months after treatment. At this rate, 6570 "eld bins were packed and shipped per month.
3. Results and discussion 3.1. Apples The benchmark fumigation variable costs for the apples with methyl bromide amounted to $2.52/t and totaled $27,050 for 10,716.12 t of apples (Table 2). Cold storage variable (direct) costs for the eight months totaled $153,900 or $14.36/t. Total variable costs, including all treatment costs, equaled $180,950 or approximately $16.89/t. Fixed (overhead) costs consisted of the
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Table 2 Apple treatment scenarios and related costs Benchmark methyl bromide
Bldg costs Chamber Cold storage CA storage Irradiation Total
Irradiation/ processor owned
Irradiation/ port owned
Regular cold storage
$183,810 $2,446,200
$2,446,200
$2,446,200
$2,446,200
$2,630,010
$6,600,000 $9,046,200
$2,446,200
$2,446,200
$182,434
$182,434
Controlled atmosphere (CA) storage
$3,039,420 $3,039,420
Annual depreciation Chamber Cold storage CA storage Irradiation Total Operating costs Total costs
$14,754 $182,434
$182,434
$197,188 $180,950 $378,138
$524,333 $706,767 $828,900 $1,535,667
$182,434 $531,900 $714,334
$182,434 $168,885 $351,319
$231,230 $230,931 $462,161
Cost/metric ton
$35.29
$143.30
$66.66
32.78
43.13
$231,230
Based on 10,716.12 t.
depreciation of the buildings and equipment. The cold storage depreciation annually amounted to $182,434, and annual depreciation of the chamber was $14,754. Total "xed costs were $197,188 or $18.40/t. For this scenario involving 27,000 "eld bins of fresh apples, total benchmark costs amounted to $378,138 or $35.29/t (Aegerter, 1998). Total variable costs for a port owned irradiation scenario for apples amounted to $531,900. Analogous to the methyl bromide scenario, the cold storage variable costs for 10,716.12 t of apples came to $153,900 or $14.36/t, and the annual depreciation amounted to $182,434 or approximately $15.44/t. Irradiation variable costs included service charges and transportation fees and amounted to $378,000 or $35.27/t. Total costs of the port owned irradiation scenario equaled $714,334 or $66.66/t (Aegerter, 1998). This scenario's cost increases were 189% of the benchmark methyl bromide scenario. Once again, the scenario allowed for regular shipments and treatments of apples up to eight months after harvest as found in the benchmark scenario. However, numerous problems arise in this treatment scenario. Trucking is an added expense along with coordinating pickup and delivery times. The irradiation facility is publicly accessible which results in the processor sharing the facilities with others and coordinating treatment times accordingly. For the packer owned irradiation scenario dealing with apples, 27,000 "eld bins (11,812.5 t) were treated in eight months for a total cost of $1,535,667 or $143.30 t (Aegerter, 1998). The irradiation facility variable costs were $62.99/t or $675,000 for the scenario involving 10,716.12 t of fresh apples. Cold storage variable costs
for the eight months totaled $153,900 or $14.36/t as true in the other scenarios. Total variable costs equaled $828,900 or roughly $77.35/t. The cold storage depreciation amounted to $182,434, and depreciation of the irradiation was $524,333. Total "xed costs were $706,767 or about $65.95/t. This scenario had costs increase 406% compared to the benchmark methyl bromide cost level. The scenario allowed for regular shipments and treatments of apples up to eight months after harvest as found in the benchmark scenario. This scenario su!ered from high operating costs and high overhead costs when the irradiation facility sat idle for the four o!-season months. The regular cold storage scenario for apples treated 27,000 "eld bins (10,716.12/t) over an eight-month period at a total cost of $351,319 or $32.78/t (Aegerter, 1998). The variable costs for cold treating apples included electricity consumption for refrigeration and labor for loading and unloading the facility. Variable costs amounted to $15.76/t and totaled $168,885 for this scenario involving 10,716.12 t of fresh apples. Fixed costs associated with this scenario amounted to $182,434 or approximately $17.02/t. Total cost which amounted to $32.78/t which was 93% of the benchmark scenario. The scenario cost less monetary-wise than the methyl bromide fumigation scenario but came at another cost, time. The apples must be held for four months which in turn limits packing and shipping to four months due to the eight-month limit on cold storage. The controlled atmosphere (CA) storage scenario used a controlled atmosphere cold storage facility as the lone treatment. The scenario for controlled atmosphere cold storage for apples treated 27,000 "eld bins (10,716.12/t)
A.F. Aegerter, R.J. Folwell / Crop Protection 19 (2000) 161}168
over an 11-month period for a total cost of $462,161 or $43.13/t (Aegerter, 1998). The variable costs came to $21.55/t or totaled $230,931. The variable costs included labor for loading and unloading the apples and electricity consumption for refrigeration and for purging and maintaining the atmosphere. The CA cold storage unit depreciation was $231,230 annually or about $21.58/t. This scenario's cost increases were 122% of the benchmark. Even though apples were required to be held three months, the scenario allowed for regular shipments of apples up to 11 months after harvest. Overall, the most favorable alternative for apples cost wise was the regular cold storage scenario. The scenario was cheaper than the benchmark scenario. However, the apples are not accessible for packing and shipping until four months after the doors were sealed to the storage unit leaving just four months to ship the apples to market. This could potentially depress apple prices if all processors followed this treatment scenario and packed apples at double the normal packing rate. Controlled atmosphere storage was more costly than regular cold storage, but apples could be packed starting three months after the doors were sealed and up to 11 months after harvest. Both irradiation scenarios allowed apples to be almost shipped immediately after harvest, but at high costs to the packer. The port owned irradiation scenario might also lead to increased transportation logistic problems with the processor forced to share the irradiation with other processors. This concept also applies to other treatment scenarios where the equipment and/or facilities could be used for more than one commodity and therefore reduce the overhead costs per unit spreading them over a larger volume.
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Table 3 Sweet cherry treatment scenarios and related costs Benchmark methyl bromide
Irradiation/ port owned
Building costs Chamber Total
$183,810 $183,810
Annual depreciation Chamber Total Operating costs Total costs
$14,754 $14,754 $25,920 $40,674
$144,000 $144,000
Cost/metric ton
$9.96
$35.27
Based on 4,082.33 t.
ciated with this scenario and no additional depreciation "xed costs. This scenario's cost increases were 354% of the benchmark. Theoretically, this scenario allowed for the commodity to be shipped to "nal destinations within 36 h of harvest. In reality, several processors may vie for access to the irradiation which could hinder throughput. With only one available alternative, cherry processors are potentially faced with a treatment cost approximately three and a half times more costly than methyl bromide fumigation. A simple alternative to solve the above problems would entail having several processors form a cooperative group that would build and own the irradiation. Processors would be able to use the irradiation when needed and then contract out the irradiation to others for the rest of the year. 3.3. Nectarines, peaches, plums
3.2. Cherries The fumigation variable costs for the cherry methyl bromide scenario came to $6.35/t and totaled $25,920 for 4,082.33 t of fresh cherries harvested (Table 3). The variable costs included the methyl bromide costs, labor, and electricity used for aeration, ventilation, and hydrocooling. Since fresh sweet cherries are not a durable commodity, there were no storage costs associated with this scenario. The "xed costs connected with this scenario were the depreciation of the chamber which amounted to $14,754 or approximately $2.61/t. This scenario quarantine treated 25,000 "eld bins (4082.33 t) of fresh sweet cherries for a total treatment cost of $40,674 or $9.96/t (Aegerter, 1998). The cherry gamma induction scenario treated 4082.33 t of cherries for a total cost of $144,000 or $35.27/t (Aegerter, 1998). The variable costs of treatment included the irradiation service charge and the transportation fee and totaled $144,000 or $36.27/t. Since cherries are not a durable commodity, there were no storage costs asso-
The soft fruit benchmark called for a methyl bromide fumigation chamber adjacent to a packing shed. The methyl bromide scenario to fumigate nectarines, peaches, and plums was for a total volume of 15,945.58 t (Table 4). This was representative of an average Californian fruit packing shed's annual throughput. Actual tonnage of each fruit variety was not considered in this scenario due to variations from packing shed to packing shed in the amount packed of each variety. Each fruit variety's boxed weight was assumed to be 11.34 kg per box which negated the need to divide each variety into its respective packed tonnage to determine treatment costs. The fumigation variable costs for the soft fruit scenario amounted to $3.96/t and totaled $63,101.43. The variable costs included the methyl bromide, labor, and electricity for aeration and ventilation. There were no additional storage costs for this scenario due to the soft fruits' perishable nature. The "xed costs for this scenario were the depreciation of the fumigation chamber and its equipment and were depreciated at an annual rate of $6787 or roughly $0.42/t. The soft fruit fumigation scenario
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Table 4 Nectarine, peach, and plum treatment scenarios and related costs Benchmark
Building costs Chamber Irradiation Total Annual depreciation Chamber Irradiation Total Operating costs Total costs Cost/metric ton
Irradiation/ processor owned
Irradiation/ port owned
$85,995 $85,995
$6,600,000 $6,600,000
$6787 $6,787 $63,101.43 $69,888.43
$524,333 $524,333 $462,500 $986,833
$562,464 $562,464
$4.38
$61.89
$35.27
Based on 15,945.58 t.
treated 15,945.58 t (1,406,160 packed boxes) of fresh nectarines, peaches, and plums, and total treatment costs amounted to $69,888.43 or $4.38/t (Aegerter, 1998). The alternative insecticidal treatment for nectarines, peaches, and plums was gamma irradiation. The scenario for the port owned irradiation involved a combined 15,945.58 t of fresh nectarines, peaches and plums harvested over a three and a half month period as was used in the processor owned facility. The only costs associated with this partial budget analysis were the transportation costs and the irradiation service charges. Total costs for this scenario amounted to $562,464 or $35.27/t (Aegerter, 1998). This scenario's cost increases were 805% of the benchmark scenario. The scenario allowed for the commodity to be shipped with the same regularity as the benchmark scenario. However, several processors may vie for the same treatment time slots at the irradiation facility which could hinder regular shipment. The processor owned irradiation scenario treated a combined 15,945.58 t of fresh nectarines, peaches, and plums over a three and a half month period. Total treatment costs amounted to $986,833 or $61.89/t (Aegerter, 1998). The irradiation facility's operating costs amounted to $462,500 including $200,000 for the maintenance of the building during the idle months. Operating costs were $29.00/t. Fixed costs comprised the annual depreciation of the irradiation facility and totaled $524,333 or $32.88/t. This scenario's cost increases were 1410% of the benchmark scenario. The continuous #ow of the product allowed the scenario to accommodate for better shipment schedules than the benchmark. However, the scenario su!ers from high overhead costs especially during the facility's idle months. The soft fruit packers have only one available alternative treatment but can choose from two treatment scen-
arios. In the port owned irradiation scenario, the packers are faced with an alternative treatment that costs eight times more than the methyl bromide treatment with uncertain availability of an accessible treatment facility. The processor/packer-owned scenario eliminates the need to coordinate treatment times with other packers and allows for the continuous #ow of the commodities through the irradiation facility. However, treatment costs for this scenario are 14 times higher than the methyl bromide benchmark scenario. The one fundamental assumption in this study was that the viable alternative treatments could e!ectively eliminate insect populations at the level comparable to methyl bromide fumigation. However, methyl bromide is currently the only worldwide accepted treatment that meets postharvest and quarantine requirements. To proceed with using these alternative treatments, further research will be needed to establish the proper quarantine requirements and documentation. It is possible that alternative treatment scenarios equal to those achieved with methyl bromide are not likely to be a socially optimal solution, i.e., there is a trade-o! between the level of screening and cost of treatment. In addition, the importing countries must also be willing to accept the alternative treatments as meeting quarantine approval. There is the possibility that other areas of the US where the pests are not found might start producing these fruits and not have to use methyl bromide to fumigate.
References Aegerter, A., 1998. Economic aspects of alternatives to methyl bromide in the postharvest and quarantine treatment of selected fresh fruits and tree nuts. M.A. thesis, Department of Agricultural Economics, Washington State University. California Department of Food and Agriculture, 1996. O$ce of pesticide consultation and analysis. Methyl Bromide: An Impact Assessment. Drake, S., 1996. USDA tree fruit research. Wenatchee, Washington. Personal communication. Mo$tt, H.R., 1996. Agricultural research service. Wapato, WA. Personal communication. Paull, R.E., Armstrong, J.W., 1994. Insect pests and fresh horticultural products: Treatments and Responses. CAB International, Wallingford, UK. Schreiber, D., 1996. Snokist Growers. Yakima, WA, Personal communication. US Department of Agriculture, USDA, 1993a. Alternatives to methyl bromide: Assessment of Research Needs and Priorities. Proceedings from the USDA Workshop on Alternatives to Methyl Bromide. Arlington, Virginia. June 29}July 1. US Department of Agriculture, USDA, 1993b. Methyl bromide substitutes and alternatives: A Research Agenda for the 1990s. Washington, DC January. US Department of Commerce, 1996. Bureau of Economic Analysis. Survey of Current Business. Washington, DC, Vol. 76 (1}2). US Environmental Protection Agency, 1995. Methyl bromide home page. Downloaded from http://www.epa.gov/docs/ozone/mbr/ mbrga.htmlCq2.
Economic aspects of alternatives to methyl bromide in the postharvest and quarantine treatment of selected fresh fruits Anthoni F. Aegerter, Raymond J. Folwell* Department of Agricultural Economics, Washington State University, PO Box 646210, Pullman, WA 99164-6210, USA Received 2 April 1999; received in revised form 20 September 1999; accepted 21 September 1999
Abstract Methyl bromide is the most commonly used postharvest and quarantine treatment of temperate fruit worldwide. Low costs, short fumigation times, and consistent quarantine security are the main reasons for methyl bromide's dominance. Recent environmental issues and laws have created the need for an alternative to methyl bromide for postharvest and quarantine treatment of fresh fruits. The objective of this study was to analyze alternative treatment scenarios with capabilities equal to those achieved by methyl bromide for treatment of apples, sweet cherries, nectarines, peaches, and plums. Partial budget scenarios for each commodity were developed to determine the methyl bromide treatment costs which established a benchmark scenario to compare to the alternative treatment scenarios of each commodity. Irradiation was the only alternative identi"ed that was available for all the fruits in this study. Cost increases for all fruit treated with irradiation ranged from two to 14 times methyl bromide costs. Controlled atmosphere storage for apples had cost increases of 122% over methyl bromide costs. Costs for regular cold storage for apples was 93% of the benchmark cost. However, the reduced costs of suppressing the pests resulted in a marketing window of only four months since there is an eight-month limit on regular cold storage and four months were required for suppressing the pests. 2000 Elsevier Science Ltd. All rights reserved. Keywords: Methyl bromide; Fumigation; Costs
1. Introduction Annually, 15}40% of the world's food supply is destroyed before consumption (USDA, 1993b). Insects are a signi"cant contributor to this food destruction. Pests infesting fresh fruits before and after harvest can render commodities unmarketable. Postharvest and quarantine treatments are used to disinfest commodities from insects after harvest and to provide quarantine security. Quarantine security can be de"ned as the degree of statistical probability needed by treatments to disinfest host commodities so that upon transport of the treated products, the targeted pests cannot become established in any area where they do not already exist. The current measure of quarantine security accepted by the United States (US) and most of its trading partners is the concept of probit9. Probit-9 requires mortality of 99.9968% or no more
* Corresponding author. Tel.: #1-509-335-5556; fax: #1-509-3351173. E-mail address: [email protected] (R.J. Folwell).
than three survivors per 100,000 treated pests. Failure of quarantine treatments may result in expensive eradication procedures, product losses due to infestation, loss of markets, and costly new quarantine treatments (Paull and Armstrong, 1994). In the recent rapid expansion of world trade, any disruption of trade can potentially be costly to all parties involved. Methyl bromide is the most commonly used treatment that consistently meets probit-9 speci"cations. The fumigant is a broad spectrum pesticide used in a wide variety of commodities. In recent years, annual US consumption of methyl bromide has been approximately 30,000 ton which accounts for 41% of the world's use (US Environmental Protection Agency, 1995). Soil fumigation to sterilize soil in preplant preparation of the soil for crop planting accounts for 85% of US consumption. Postharvest and quarantine treatments of fruits, nuts, vegetables, and grains account for the remaining 15% (USDA, 1993b). Methyl bromide is the most widely used fumigant for postharvest and quarantine treatments of agricultural commodities and is the only accepted treatment for temperate fruit worldwide that meets
0261-2194/00/$ - see front matter 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 2 6 1 - 2 1 9 4 ( 9 9 ) 0 0 0 8 1 - 2
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international phytosanitary requirements for freedom from insect infestations (California Department of Food and Agriculture, 1996). However, there are some major concerns in the applications of methyl bromide. It is an extremely dangerous and deadly fumigant, and special care is needed for those people that are conducting the applications. Scienti"c studies have linked methyl bromide to ozone depletion which have raised questions regarding the continued use of the fumigant. Under the Montreal Protocol, methyl bromide was initially to be phased out in the US under the US Clean Air Act by January 1, 2001. The 1999 federal budget made the US phase out identical to that required by the Montreal Protocol for developed countries and allowed for the same exemption. The schedule for phase out in developed countries and the Montreal Protocol is: (1) 25% reduction in 1999; (2) 25% reduction in 2001; (3) 20% reduction in 2003; (4) and a complete phase out in 2005. Exemptions include quarantine, critical uses, and certain preshipment uses. Numerous problems in postharvest and quarantine treatments will arise with the eventual loss of methyl bromide. Farmers in developed countries such as the US will be at a competitive disadvantage when competing with products produced in developing countries where methyl bromide will be available for several years after it is phased out in the US. There will be increased competition from countries not banning methyl bromide. The loss of methyl bromide could create potential trade barriers for the US in both the domestic and foreign export markets. Without methyl bromide or an acceptable alternative, the US will not be able to export to these markets. Alternative postharvest and quarantine treatments must be as e!ective as methyl bromide and be able to meet environmental and regulatory requirements. Alternatives should be able to combat the abilities of pests to develop resistances to treatments through rapid reproduction rates and short lifecycles. Treatments need to be developed to eradicate all life stages of insects that may be found on the product exported with equal success. The characteristics of the host commodity, especially tolerance to treatments, should also be considered when implementing alternative treatments. The timeliness or the time needed to carry out the content of each alternative treatment is another important consideration. The treatment time must not signi"cantly reduce the time available to market a product within its useful life. The downward pressure on prices from marketing the commodity in a shorter window of opportunity could be an economic disaster. This study considered gamma irradiation, regular cold storage, and controlled atmosphere storage as potential commercially available alternatives to methyl bromide in postharvest and quarantine treatments of selected fresh fruits. Other available alternative treatments that were
Table 1 Postharvest and quarantine pests of economic importance Tree variety
Common name
Scienti"c name
Apples
Codling moth Mediterranean fruit #y Oriental fruit #y San Jose scale Apple maggot
Cydia pomonella Ceratitis capitata Dacus dorsalis Aspidiotus perniciosus Rhagoletis pomonella
Cherries
Codling moth Mediterranean fruit #y Oriental fruit #y Cherry fruit #y
Cydia pomonella Ceratitis capitata Dacus dorsalis Rhagoletis cingulata
Nectarines/ Peaches/Plums
Peach twig borer Codling moth Oriental fruit moth Walnut husk #y Plum Curculio Mediterranean fruit #y
Anarsia lineatella Cydia pomonella Grapholitha molesta Rhagoletis completa Conotrachelus nenuphar Ceratitis capitata
Adapted from: Paull and Armstrong, 1994.
not analyzed included electron beam irradiation, phosphine fumigation, heat treatments, and the systems approach. Electron beam irradiation was not a viable alternative due its low degree of penetration and lack of commercial applications in high volume packing operations. Phosphine can only be used on tree nuts or dried fruit due to its detrimental e!ects on fresh fruits. With some exceptions the available heat treatments have been shown to be e!ective against temperate insects. However, possible damage to the #esh of some fresh fruits may compromise the fruit quality. Presently, the only commercial heat treatment applications are for the disinfestation of tropical fruits. The systems approach which combines cultural practices with other activities to suppress the insect populations is presently under development, and costs are unquanti"able due to the broad scope of varying activities and lack of total implementation. The postharvest and quarantine treatments of apples, cherries, plums, nectarines, and peaches, along with the insect pests commonly associated with these commodities are presented in Table 1. This study consists of an economic analysis of potential, commercially available alternatives, for the postharvest and quarantine treatment of apples, cherries, nectarines, peaches, and plums. The alternatives need capabilities equal or similar to those achieved by methyl bromide in terms of time required and pest mortality. Public, legal, and regulatory acceptance, as well as environmental impacts and safety factors, will also have to be addressed before any techniques are accepted. The goal of this study was to make comparisons between alternatives on an economic basis.
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2. Methodology 2.1. Budgeting techniques, assumptions, and alternative treatments Methyl bromide fumigation costs for each commodity were estimated to establish a benchmark scenario to compare alternative treatment scenarios. Treatment scenarios were developed on a commercial scale for the technically feasible alternatives, and costs were determined using current industry practices. Several assumptions were made to facilitate comparability among scenarios. Methyl bromide was assumed to be unconditionally banned. Therefore, methyl bromide recycling scenarios were not considered. Each scenario represented a single step in the marketing channel, and costs were estimated utilizing economic engineering techniques. The speci"cations for the buildings and equipment are discussed for each scenario since they were di!erent for some of the fruits. Rather than developing multiple quantity scenarios for each commodity, the chosen scenario for each commodity represents an average quantity or most commonly occurring quantity situation. Building and equipment costs were adjusted to 1995 dollars using a price index for private "xed investment (US Department of Commerce, Bureau of Economic Analysis, 1996). All buildings were straight-line depreciated over 15 years with no salvage value, and all machinery was straight-line depreciated over ten years with no salvage value. The depreciation schedules are industry accepted and promote conservative cost estimates. Apples were considered a storable commodity whereas cherries, plums, peaches, and nectarines were assumed to be packed and shipped immediately after harvest due to their high perishability. 2.2. Methyl bromide fumigation (benchmark) Methyl bromide fumigation is an advantageous procedure for processors in the postharvest and quarantine treatment of fruits. The injection process and the stabilization of concentrations usually take 30 min. Most fumigation treatments can be accomplished in 2}24 h of exposure. A fumigation chamber can be any airtight enclosure from a tarp-covered structure to a cement building. Perishable commodities can take 24}36 h to move from orchard to market using methyl bromide fumigation (Schreiber, 1996). The product is immediately susceptible to reinfestation with methyl bromide fumigation as well as the alternatives discussed here. Methyl bromide fumigation of apples is currently a rare occurrence. Japan and Korea are the only countries currently demanding probit-9 security for codling moth in apples. Their combined imports amount to less than 2% of total US apple exports. Shipments of apples to these countries are relatively small and spread out over
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the marketing year resulting in small applications of methyl bromide. It was assumed that the apples treated with methyl bromide were handled by one "rm since the small quantity has a tendency to distort fumigation costs by spreading large "xed costs over a small tonnage of apples. This assumption allowed for a more realistic evaluation of costs. In the methyl bromide scenario for apples, a 1699 cm fumigation chamber and a 6118 m regular cold storage unit were utilized. The chamber had the capacity to fumigate 725 "eld bins per treatment, and the cold storage unit accommodated 27,000 "eld bins with 397 k per "eld bin in two rooms of equal size. For simplicity, cold storage apples were assumed to be unloaded and packed starting in the "rst month of storage. However, apples destined for Japan and Korea were assumed held for at least 55 days in cold storage at 2.23C. Therefore apples that are ready for marketing before their time requirement would be shipped to other markets and then the fruit removed from storage after the time requirements could be shipped to Japan and Korea. Apples have a shelf life of eight months in regular cold storage, and it was assumed that the apples were unloaded at a constant rate over the eight months. At this rate, 3375 "eld bins could be fumigated and packed per month. With a 725bin capacity chamber, a fumigation occurred every six days. The fumigation chamber was "lled with bins from the cold storage unit, and the methyl bromide was applied and ventilated in a 24-h period. The chamber was then unloaded as the apples were packed and shipped over a "ve-day period before the next fumigation. At the end of month four, the "rst room in the cold storage unit was empty, and its refrigeration unit was shut down. The second room was opened and emptied by the end of month eight. Fumigating fresh sweet cherries for codling moth and other insects with methyl bromide is a standard routine in postharvest operations. Since fresh cherries are an extremely perishable commodity, methyl bromide o!ers a quick and easy insecticidal treatment for both export and domestic use. Japan, South Korea, Mexico, Egypt, Peru, Pakistan, and British Columbia, along with several US states all require methyl bromide fumigation of fresh cherries. For this study, it was assumed that cherries were harvested over a three-week period and shipped immediately after harvest due to the high perishability of the fruit. In the methyl bromide sweet cherry scenario, a 1699 cm fumigation chamber was located adjacent to the packing house. The chamber had the capacity of handling 1370 "eld bins per treatment. As the cherries were brought in from the orchards, the chamber was "lled with "eld bins. The cherries were hydro-cooled in the chamber in preparation for the methyl bromide application. Once applied, the methyl bromide was allowed to disinfest the cherries overnight, and the chamber was
164
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ventilated the next morning. The cherries were then unloaded, packed, and prepared for shipment. After the chamber was emptied, the process was repeated with the fresh cherries picked that day. Soft fruits (nectarines, peaches, and plums) are fumigated with methyl bromide as a quarantine treatment but not with the same regularity as sweet cherries. The only soft fruit fumigated are those sent to the states or countries demanding quarantine security. Japan and South Korea require methyl bromide fumigation of the soft fruits to ensure quarantine security from codling moth. Mexico, Egypt, Pakistan, Peru, British Columbia, California, Texas, Florida, and Arizona, require quarantine treatments against fruit #ies in the soft fruits. In this study, it was assumed that all soft fruits were to be fumigated before shipment to either export or domestic markets and that the total harvest period for the three fruits covered three and a half months. Packing houses were assumed to pack nectarines, peaches, and plums on individual packing lines throughout this harvest period. Once packed, all three fruit varieties were placed in the chamber as they came o! the packing line and then fumigated. Nectarines are usually harvested from mid June through late August, peaches are harvested from early June to late September, and plums are picked from late May through late September. For the soft fruit methyl bromide scenario, an 849.5 cm fumigation chamber with no refrigeration unit was located adjacent to the packing house. Soft fruit does not require refrigeration for fumigation purposes so the chamber was not out"tted with a refrigeration unit. The chamber had the capacity to fumigate 7810 boxes of packed fruit per treatment. Soft fruits are susceptible to bruising, and extra care in handling is required to minimize blemishes. Packing houses normally sort and pack soft fruit before fumigating them to minimize bruising. After the fruit was packed, it was placed in the chamber and fumigated. Treatment times lasted less than 12 h including time for loading and unloading the packed commodities. This allowed for the use of a smaller chamber, two fumigations per 24 h period, and better timing logistics in shipping the commodity to its "nal destination. 2.3. Irradiation (alternative) The irradiation process involves the use of ionizing radiation to control insects infesting the commodity at a single point in the commodity's transit. Irradiation sources can be either gamma particles, usually from cobalt60, or electron beam particles formed from electron beam accelerators. Irradiation processes are not temperature dependent, can treat sealed containers, and leave no residues (USDA, 1993a). Irradiation has been proven to lengthen the shelf life and/or delay ripening in several food commodities. Irradiation does not cause a high,
immediate mortality rate but rather sterilizes most insects. This will require quarantine o$cials to accept products and commodities infested with live, though sterile, adult insects or live immature insects incapable of reaching the adult stage. The lack of residuals makes the commodities susceptible to reinfestation as is the case with methyl bromide. This procedure is complicated by the fact that fruits can only be irradiated once according to regulatory rules. E!ectiveness of this treatment is commodity speci"c in regards to the level of tolerable exposure. Two scenarios were developed for the irradiation of apples. One scenario assumed that the apple packer owned the gamma irradiation facility whereas in the second scenario the packer shipped boxed apples to a port owned facility to be irradiated and then shipped the apples to their "nal destinations. A 2415.5 m irradiation facility and a 6118.0 m cold storage unit with two rooms of equal size were used in the packer owned irradiation scenario. For simplicity in this study, cold storage apples were assumed to be unloaded and packed starting in the "rst month of storage. Apples have a shelf life of eight months in regular cold storage, and it was assumed that the apples were unloaded at a constant rate over the eight months. At this rate, 3375 "eld bins could be irradiated and packed per month. Three trucks of apples, approximately 18 t per truck, can easily be irradiated in a day to meet this unloading rate. For this scenario, it was assumed that the irradiation was only used for apples and was shut down after all the apples were treated. In the port owned irradiation scenario for apples, the packer owned a 6118.0 m regular cold storage facility. The facility had the capacity to hold 27,000 apple "eld bins in two rooms of equal size. For simplicity in this study, cold storage apples were unloaded and packed starting in the "rst month of storage. Apples with a shelf life of eight months in regular cold storage, and it was assumed that the apples were unloaded at a constant rate over the eight months. At this rate, 3375 bins could be packed and irradiated per month. Unlike the packer owned irradiation scenario, the packer unloaded the "eld bins and boxed the apples before trucking them to be irradiated and then delivered to their "nal destinations. This prevented shipping the irradiated apples back to the packer to be boxed and shipped to their "nal destinations. The only feasible alternative treatment for cherries was gamma irradiation. Fresh cherries cannot be held in regular cold storage or controlled atmosphere storage long enough to meet quarantine requirements. For the sweet cherry scenario, it was assumed that the packer would irradiate cherries at a port owned facility because it is cost prohibitive to build an irradiation that would be used only for the three weeks during harvest. The cherries were hauled from the orchards in "eld bins and trucked
A.F. Aegerter, R.J. Folwell / Crop Protection 19 (2000) 161}168
to the packing shed to be sorted and boxed. After packing, the cherries were trucked to a port owned irradiation facility for treatment before "nal shipment. The only feasible alternative treatment for nectarines, peaches, and plums was gamma irradiation. Nectarines, peaches, and plums cannot be held in regular cold storage or controlled atmosphere storage long enough to meet quarantine requirements. One scenario assumed that the soft fruit packer owned the irradiation facility whereas in the second scenario the packer shipped boxed fruit to a port owned facility to be irradiated. A 2415.5 m irradiation facility neighboring a packing shed was used in the processor/packer owned irradiation scenario. The soft fruits arrived at the packing shed from the orchards where they were sorted and boxed. The boxed fruits were then conveyed from the packing shed through the irradiation. In the port owned irradiation scenario, the soft fruits were trucked to the packing shed from the orchards. At the packing shed, the fruits were sorted and boxed. The boxed fruit was then trucked to the port owned irradiation facility and treated. Once treated, the fruits were transported to their "nal destinations. 2.4. Controlled atmosphere cold storage (alternative) Controlled atmosphere cold storage (CA) is a process of modifying the air in a refrigerated enclosure to su!ocate insects by purging or displacement of oxygen. The resulting atmosphere has a low oxygen/high carbon dioxide or high nitrogen concentration. CA storage promotes a longer storage life for commodities than regular cold storage. The treatment has proven its e$cacy, leaves no residues, and is environmentally safe. However, this treatment alternative has high capital costs, is temperature dependent, and is slow acting. The commodity is also susceptible to immediate reinfestation after removal from storage as with the other alternatives considered. Commodity treatment is limited to the space available and requires well-sealed chambers. CA is also commodity speci"c based on perishability. Apples in controlled atmosphere cold storage must be held for 90 days at 0}1.673C and in an atmosphere with less than 2% oxygen and less than 3% carbon dioxide. In these conditions, pests of all stages are successfully eradicated (Drake, 1996). In the controlled atmosphere storage scenario, a 5258.3 sm controlled atmosphere cold storage facility was used as the treatment facility. The facility had a total volume of 49,667.7 cm, could hold 27,000 apple "eld bins, and had eight rooms of equal size. As each room was "lled, the doors were sealed, and the oxygen was drawn down. The draw down took approximately 24 h per room to complete. To meet probit-9 speci"cations, the apples were held for 90 days after the purging was complete. Apples have a shelf life of 11 months in controlled atmosphere cold storage. It was
165
assumed that the apples were held in storage for the "rst three months (90 days) and then unloaded at a constant rate over the next eight months. At this rate, 3375 bins were packed and shipped each month. 2.5. Regular cold storage (alternative) Regular cold storage is the refrigeration of commodities at temperatures that e!ectively kill pests. Most fresh commodities are held at 0.0}1.103C without any change in atmospheric gases. Cold storage is a simple procedure, leaves no residues, and is environmentally safe. Drawbacks include that it is a slow process and is limited to the storage space available and to the storage life of the commodity. The treatment process is commodity speci"c in terms of e!ectiveness and is often used in combination with other treatments to meet probit-9 speci"cations and time constraints. Potential apple alternative treatment scenarios included gamma irradiation, stand alone regular cold storage, and controlled atmosphere cold storage. Regular cold storage as a stand alone treatment requires that the apples in the storage facility be held for 120 days at temperatures ranging from 0}1.103C to meet probit-9 speci"cations. This temperature range is e!ective for eradicating insects in the non-diapausing stages and the egg stage. Insects in the diapausing stage can withstand the extreme temperatures and may survive the storage temperatures. In apples, diapausing stages are not usually found in the stored fruit so the cold storage treatment can be used as an e!ective means of reaching probit-9 levels (Mo$tt, 1996). The regular cold storage scenario for apples utilized a 6118 m cold storage unit as the lone treatment apparatus. The cold storage facility had the capacity to accommodate 27,000 apple "eld bins in two equal size rooms. Once loaded, the doors of the storage unit were sealed for 120 days. Apples have a shelf life of eight months in regular cold storage so the apples had to be unloaded within four months of the "nished treatment time. In this scenario, it was assumed that apples would be unloaded at a constant rate over the four months after treatment. At this rate, 6570 "eld bins were packed and shipped per month.
3. Results and discussion 3.1. Apples The benchmark fumigation variable costs for the apples with methyl bromide amounted to $2.52/t and totaled $27,050 for 10,716.12 t of apples (Table 2). Cold storage variable (direct) costs for the eight months totaled $153,900 or $14.36/t. Total variable costs, including all treatment costs, equaled $180,950 or approximately $16.89/t. Fixed (overhead) costs consisted of the
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Table 2 Apple treatment scenarios and related costs Benchmark methyl bromide
Bldg costs Chamber Cold storage CA storage Irradiation Total
Irradiation/ processor owned
Irradiation/ port owned
Regular cold storage
$183,810 $2,446,200
$2,446,200
$2,446,200
$2,446,200
$2,630,010
$6,600,000 $9,046,200
$2,446,200
$2,446,200
$182,434
$182,434
Controlled atmosphere (CA) storage
$3,039,420 $3,039,420
Annual depreciation Chamber Cold storage CA storage Irradiation Total Operating costs Total costs
$14,754 $182,434
$182,434
$197,188 $180,950 $378,138
$524,333 $706,767 $828,900 $1,535,667
$182,434 $531,900 $714,334
$182,434 $168,885 $351,319
$231,230 $230,931 $462,161
Cost/metric ton
$35.29
$143.30
$66.66
32.78
43.13
$231,230
Based on 10,716.12 t.
depreciation of the buildings and equipment. The cold storage depreciation annually amounted to $182,434, and annual depreciation of the chamber was $14,754. Total "xed costs were $197,188 or $18.40/t. For this scenario involving 27,000 "eld bins of fresh apples, total benchmark costs amounted to $378,138 or $35.29/t (Aegerter, 1998). Total variable costs for a port owned irradiation scenario for apples amounted to $531,900. Analogous to the methyl bromide scenario, the cold storage variable costs for 10,716.12 t of apples came to $153,900 or $14.36/t, and the annual depreciation amounted to $182,434 or approximately $15.44/t. Irradiation variable costs included service charges and transportation fees and amounted to $378,000 or $35.27/t. Total costs of the port owned irradiation scenario equaled $714,334 or $66.66/t (Aegerter, 1998). This scenario's cost increases were 189% of the benchmark methyl bromide scenario. Once again, the scenario allowed for regular shipments and treatments of apples up to eight months after harvest as found in the benchmark scenario. However, numerous problems arise in this treatment scenario. Trucking is an added expense along with coordinating pickup and delivery times. The irradiation facility is publicly accessible which results in the processor sharing the facilities with others and coordinating treatment times accordingly. For the packer owned irradiation scenario dealing with apples, 27,000 "eld bins (11,812.5 t) were treated in eight months for a total cost of $1,535,667 or $143.30 t (Aegerter, 1998). The irradiation facility variable costs were $62.99/t or $675,000 for the scenario involving 10,716.12 t of fresh apples. Cold storage variable costs
for the eight months totaled $153,900 or $14.36/t as true in the other scenarios. Total variable costs equaled $828,900 or roughly $77.35/t. The cold storage depreciation amounted to $182,434, and depreciation of the irradiation was $524,333. Total "xed costs were $706,767 or about $65.95/t. This scenario had costs increase 406% compared to the benchmark methyl bromide cost level. The scenario allowed for regular shipments and treatments of apples up to eight months after harvest as found in the benchmark scenario. This scenario su!ered from high operating costs and high overhead costs when the irradiation facility sat idle for the four o!-season months. The regular cold storage scenario for apples treated 27,000 "eld bins (10,716.12/t) over an eight-month period at a total cost of $351,319 or $32.78/t (Aegerter, 1998). The variable costs for cold treating apples included electricity consumption for refrigeration and labor for loading and unloading the facility. Variable costs amounted to $15.76/t and totaled $168,885 for this scenario involving 10,716.12 t of fresh apples. Fixed costs associated with this scenario amounted to $182,434 or approximately $17.02/t. Total cost which amounted to $32.78/t which was 93% of the benchmark scenario. The scenario cost less monetary-wise than the methyl bromide fumigation scenario but came at another cost, time. The apples must be held for four months which in turn limits packing and shipping to four months due to the eight-month limit on cold storage. The controlled atmosphere (CA) storage scenario used a controlled atmosphere cold storage facility as the lone treatment. The scenario for controlled atmosphere cold storage for apples treated 27,000 "eld bins (10,716.12/t)
A.F. Aegerter, R.J. Folwell / Crop Protection 19 (2000) 161}168
over an 11-month period for a total cost of $462,161 or $43.13/t (Aegerter, 1998). The variable costs came to $21.55/t or totaled $230,931. The variable costs included labor for loading and unloading the apples and electricity consumption for refrigeration and for purging and maintaining the atmosphere. The CA cold storage unit depreciation was $231,230 annually or about $21.58/t. This scenario's cost increases were 122% of the benchmark. Even though apples were required to be held three months, the scenario allowed for regular shipments of apples up to 11 months after harvest. Overall, the most favorable alternative for apples cost wise was the regular cold storage scenario. The scenario was cheaper than the benchmark scenario. However, the apples are not accessible for packing and shipping until four months after the doors were sealed to the storage unit leaving just four months to ship the apples to market. This could potentially depress apple prices if all processors followed this treatment scenario and packed apples at double the normal packing rate. Controlled atmosphere storage was more costly than regular cold storage, but apples could be packed starting three months after the doors were sealed and up to 11 months after harvest. Both irradiation scenarios allowed apples to be almost shipped immediately after harvest, but at high costs to the packer. The port owned irradiation scenario might also lead to increased transportation logistic problems with the processor forced to share the irradiation with other processors. This concept also applies to other treatment scenarios where the equipment and/or facilities could be used for more than one commodity and therefore reduce the overhead costs per unit spreading them over a larger volume.
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Table 3 Sweet cherry treatment scenarios and related costs Benchmark methyl bromide
Irradiation/ port owned
Building costs Chamber Total
$183,810 $183,810
Annual depreciation Chamber Total Operating costs Total costs
$14,754 $14,754 $25,920 $40,674
$144,000 $144,000
Cost/metric ton
$9.96
$35.27
Based on 4,082.33 t.
ciated with this scenario and no additional depreciation "xed costs. This scenario's cost increases were 354% of the benchmark. Theoretically, this scenario allowed for the commodity to be shipped to "nal destinations within 36 h of harvest. In reality, several processors may vie for access to the irradiation which could hinder throughput. With only one available alternative, cherry processors are potentially faced with a treatment cost approximately three and a half times more costly than methyl bromide fumigation. A simple alternative to solve the above problems would entail having several processors form a cooperative group that would build and own the irradiation. Processors would be able to use the irradiation when needed and then contract out the irradiation to others for the rest of the year. 3.3. Nectarines, peaches, plums
3.2. Cherries The fumigation variable costs for the cherry methyl bromide scenario came to $6.35/t and totaled $25,920 for 4,082.33 t of fresh cherries harvested (Table 3). The variable costs included the methyl bromide costs, labor, and electricity used for aeration, ventilation, and hydrocooling. Since fresh sweet cherries are not a durable commodity, there were no storage costs associated with this scenario. The "xed costs connected with this scenario were the depreciation of the chamber which amounted to $14,754 or approximately $2.61/t. This scenario quarantine treated 25,000 "eld bins (4082.33 t) of fresh sweet cherries for a total treatment cost of $40,674 or $9.96/t (Aegerter, 1998). The cherry gamma induction scenario treated 4082.33 t of cherries for a total cost of $144,000 or $35.27/t (Aegerter, 1998). The variable costs of treatment included the irradiation service charge and the transportation fee and totaled $144,000 or $36.27/t. Since cherries are not a durable commodity, there were no storage costs asso-
The soft fruit benchmark called for a methyl bromide fumigation chamber adjacent to a packing shed. The methyl bromide scenario to fumigate nectarines, peaches, and plums was for a total volume of 15,945.58 t (Table 4). This was representative of an average Californian fruit packing shed's annual throughput. Actual tonnage of each fruit variety was not considered in this scenario due to variations from packing shed to packing shed in the amount packed of each variety. Each fruit variety's boxed weight was assumed to be 11.34 kg per box which negated the need to divide each variety into its respective packed tonnage to determine treatment costs. The fumigation variable costs for the soft fruit scenario amounted to $3.96/t and totaled $63,101.43. The variable costs included the methyl bromide, labor, and electricity for aeration and ventilation. There were no additional storage costs for this scenario due to the soft fruits' perishable nature. The "xed costs for this scenario were the depreciation of the fumigation chamber and its equipment and were depreciated at an annual rate of $6787 or roughly $0.42/t. The soft fruit fumigation scenario
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Table 4 Nectarine, peach, and plum treatment scenarios and related costs Benchmark
Building costs Chamber Irradiation Total Annual depreciation Chamber Irradiation Total Operating costs Total costs Cost/metric ton
Irradiation/ processor owned
Irradiation/ port owned
$85,995 $85,995
$6,600,000 $6,600,000
$6787 $6,787 $63,101.43 $69,888.43
$524,333 $524,333 $462,500 $986,833
$562,464 $562,464
$4.38
$61.89
$35.27
Based on 15,945.58 t.
treated 15,945.58 t (1,406,160 packed boxes) of fresh nectarines, peaches, and plums, and total treatment costs amounted to $69,888.43 or $4.38/t (Aegerter, 1998). The alternative insecticidal treatment for nectarines, peaches, and plums was gamma irradiation. The scenario for the port owned irradiation involved a combined 15,945.58 t of fresh nectarines, peaches and plums harvested over a three and a half month period as was used in the processor owned facility. The only costs associated with this partial budget analysis were the transportation costs and the irradiation service charges. Total costs for this scenario amounted to $562,464 or $35.27/t (Aegerter, 1998). This scenario's cost increases were 805% of the benchmark scenario. The scenario allowed for the commodity to be shipped with the same regularity as the benchmark scenario. However, several processors may vie for the same treatment time slots at the irradiation facility which could hinder regular shipment. The processor owned irradiation scenario treated a combined 15,945.58 t of fresh nectarines, peaches, and plums over a three and a half month period. Total treatment costs amounted to $986,833 or $61.89/t (Aegerter, 1998). The irradiation facility's operating costs amounted to $462,500 including $200,000 for the maintenance of the building during the idle months. Operating costs were $29.00/t. Fixed costs comprised the annual depreciation of the irradiation facility and totaled $524,333 or $32.88/t. This scenario's cost increases were 1410% of the benchmark scenario. The continuous #ow of the product allowed the scenario to accommodate for better shipment schedules than the benchmark. However, the scenario su!ers from high overhead costs especially during the facility's idle months. The soft fruit packers have only one available alternative treatment but can choose from two treatment scen-
arios. In the port owned irradiation scenario, the packers are faced with an alternative treatment that costs eight times more than the methyl bromide treatment with uncertain availability of an accessible treatment facility. The processor/packer-owned scenario eliminates the need to coordinate treatment times with other packers and allows for the continuous #ow of the commodities through the irradiation facility. However, treatment costs for this scenario are 14 times higher than the methyl bromide benchmark scenario. The one fundamental assumption in this study was that the viable alternative treatments could e!ectively eliminate insect populations at the level comparable to methyl bromide fumigation. However, methyl bromide is currently the only worldwide accepted treatment that meets postharvest and quarantine requirements. To proceed with using these alternative treatments, further research will be needed to establish the proper quarantine requirements and documentation. It is possible that alternative treatment scenarios equal to those achieved with methyl bromide are not likely to be a socially optimal solution, i.e., there is a trade-o! between the level of screening and cost of treatment. In addition, the importing countries must also be willing to accept the alternative treatments as meeting quarantine approval. There is the possibility that other areas of the US where the pests are not found might start producing these fruits and not have to use methyl bromide to fumigate.
References Aegerter, A., 1998. Economic aspects of alternatives to methyl bromide in the postharvest and quarantine treatment of selected fresh fruits and tree nuts. M.A. thesis, Department of Agricultural Economics, Washington State University. California Department of Food and Agriculture, 1996. O$ce of pesticide consultation and analysis. Methyl Bromide: An Impact Assessment. Drake, S., 1996. USDA tree fruit research. Wenatchee, Washington. Personal communication. Mo$tt, H.R., 1996. Agricultural research service. Wapato, WA. Personal communication. Paull, R.E., Armstrong, J.W., 1994. Insect pests and fresh horticultural products: Treatments and Responses. CAB International, Wallingford, UK. Schreiber, D., 1996. Snokist Growers. Yakima, WA, Personal communication. US Department of Agriculture, USDA, 1993a. Alternatives to methyl bromide: Assessment of Research Needs and Priorities. Proceedings from the USDA Workshop on Alternatives to Methyl Bromide. Arlington, Virginia. June 29}July 1. US Department of Agriculture, USDA, 1993b. Methyl bromide substitutes and alternatives: A Research Agenda for the 1990s. Washington, DC January. US Department of Commerce, 1996. Bureau of Economic Analysis. Survey of Current Business. Washington, DC, Vol. 76 (1}2). US Environmental Protection Agency, 1995. Methyl bromide home page. Downloaded from http://www.epa.gov/docs/ozone/mbr/ mbrga.htmlCq2.