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Development of cotton-pest management in Zimbabwe
CROP PROTECTION (1983) 2 (2), 247-250
Development of cotton-pest m a n a g e m e n t in Zimbabwe M. W. BURGESS
Cotton Training Centre, PO Box 530, Kadoma, Zimbabwe Use of insecticides on cotton is kept to a minimum in Zimbabwe by the recommendation that applications are timed on the basis of routine crop-inspection (scouting) data. Greater acceptance of field scouting by large-scale cotton producers was achieved by providing training for farm scouts. The syllabus for courses financed from a crop levy included recognition of insect pests and methods of recording their numbers. Subsequently, courses on data interpretation improved the timing of spraying, but scouting efficiency was increased most markedly by an on-farm check scouting scheme. Small-scale cotton farmers also are now provided with courses. Training schemes have been an important factor in the adoption of a pest-management programme. Cotton production has increased from less than 3000 t of lint in 1964 to over 70 000 t in 1982. ABSi"RACT.
Cotton was first grown commercially in Zimbabwe in 1924, but because effective chemical pest control was practically non-existent up to the late 1950s, cotton yields were variable and seldom exceeded 400 kg/ha seed cotton (McKinstry, 1959). Extension trials carried out in the 1960-61 and 1961-62 seasons (Tunstall and Matthews, 1965a,b) indicated that yield increases of up to 1500 kg/ha seed cotton were possible if the crop was sprayed regularly. T h e greatest response to spraying was obtained on crops provided with a high standard of crop husbandry. T h e main pests at that time were jassid (Empoasca facialis), heliothis bollworm (Heliothis armigera), red bollworm (Diparopsis castanea) and stainers (Dysdercus species). T h e large-scale commercial growers, who d i d p r o v i d e the requisite high standard of crop husbandry, were quick to see the advantage of this, and their Association published the first Cotton Handbook, in conjunction with Gatooma (now Kadoma) Research Station, in 1964 (Zimbabwe Commercial Cotton Growers Association, 1964). T h i s handbook has since become the standard cotton textbook for both growers and extension workers in Zimbabwe, and to a lesser extent in neighbouring countries. Over 75~o of Zimbabwe's cotton crop is rain grown and the seasonal variability of crop growth, pest incidence and the interaction of both, has made it extremely difficult to formulate simple recommendations for effective pest control while 0261-2194[83/02/0247-04503.00 © 1983 Butterworth & Co (Publishers) Ltd
248
Development of cotton-pest managementin Zimbabwe
avoiding unnecessary and potentially damaging spray applications which could be uneconomic as well as accelerating the build-up of resistance. Recommendations, therefore, depend upon considerable skill both in the collection of scouting (monitoring) data and in the interpretation of weekly scouting counts and their trends (Gledhill, 1976). This level of expertise has been possible only because the high standard of cotton research in Zimbabwe has been backed up by a most effective and well-trained extension service. As early as 1963 a specialist cotton advisory officer was posted to the Government Cotton Research Station at Kadoma (formerly Gatooma), initiating a successful arrangement between research and extension that has ensured already that farmers have had ready access to the results of latest research in all aspects of cotton production. This has contributed in no small way to the success of the cotton industry in Zimbabwe, which is illustrated by the fact that the average yield of seed Cotton on commercial cotton farms increased from 650 kg/ha to just under 1750 kg/ha during the period 1960-70. From the early 1960s, farmers were encouraged to spray their cotton on the basis of scouting results, but the majority still followed calendar schedules and even as late as 1971 it was still apparent that there were large variations in the number of applications that were used in similar pest situations (Burgess, 1971). Nevertheless, surveys carried out in 1971/72 indicated that commercial cotton growers were able to make substantial savings by employing trained cotton scouts and spraying only when pest damage thresholds were exceeded. It was clearly demonstrated that spraying on a calender schedule during the pre-bloom period of cotton growth was committing growers to up to Z$30/ha in chemical and application costs without any increase in yield, and in certain situations premature termination of spray programmes often resulted in serious bollworm damage to the top crop. In one case this was estimated at 20% of the total crop yield. Cotton extension objectives for commercial growers were redefined and intensive, specialized cotton training for farm scouts was started in 1972. In 1974 the then Rhodesia Cotton Growers' Association, which is financed from a self-imposed levy of 1"4~o of the value of growers' seed cotton, took over responsibility for these courses and initiated the development of the Cotton Production Training Unit at Kadoma in close co-operation with the Cotton Research Institute, also at Kadoma. The course syllabus included instruction in the recognition, life histories and feeding habits of the two key pests (Heliothis armigera and Diparopsis castanea) and of the two minor bollworm pests (Earias species and Pectinophora gossypiella) as well as eight sucking pests (Empoasca facialis, Aphis gossypii, Bemisia tabaci, Taylorilygus vosseleri, Helopeltis, Tetranychus, Thrips, Dysdercus and Oxycarenas species), several leaf-eating insects and five of the most commonly occurring predators (Chrysopa, coccinelid, syrphid, Phonoctonus and arachnid species). These courses also included methods of assessing field levels of these pests and of beneficial insects, based on scoUting a minimum of 24 average-sized plants on fields up to 20 ha in area. Methods of recording insect numbers, as well as the correct methods of application of insecticides and, to a lesser degree, methods of monitoring the effectiveness of aerial application, were included in the syllabus. Farmers were also encouraged to send their scouts on refresher courses during subsequent years to ensure that they were brought up to date in the latest techniques. In 1974, 641 farm employees were trained in cotton scouting methods~ By the end of 1977, 2819 people had received training on these courses and over 40% of the cotton grown by large-scale commercial farmers was being scouted regularly. However, it was
M. W. BURGESS
249
apparent from observations that there were two areas of weakness in the pest-management systems employed by many leading commercial farmers. The first was that the cotton scouts were not being adequately checked in the field and this was leading to inaccuracies in their data collection. The second area of weakness was in the farmer's interpretation of that data, which led to poor timing of pest-control operations. As a result, pilot schemes to check scouting were started in order to investigate the possibility of offering a comprehensive pest-management service to farmers to enable them to make better use of the latest recommendations and to maximize the profitability of cotton production. The result of these pilot schemes was the formation of an on-farm scouting and crop development recording service which, in 1978, involved over 180 farmers growing 22 000 ha of cotton. By 1980 nearly 30 000 ha were being regularly checked in this scheme, which represented approximatdy 25~o of the area under cotton in Zimbabwe and, according to surveys, was worth nearly Z$500 000 annually to the industry at an approximate cost to the farmers of Z$45 000. Farmers who joined the scheme were encouraged to attend pest-management courses at Kadoma and to employ at least two trained scouts. The Association, in turn, provided a team of trained scouts who were based throughout the country to visit scheme members once a week in order to check the farmer's scouting results. Any inaccuracies in data collection were quickly rectified. Scouting efficiency improved dramatically throughout the country as a result of this service, which cost the growers concerned Z$1/ha initially. Crop-monitoring records in the form of growth analysis were also collected, providing a back-up to identify possible causes of crop loss and assisting agronomic decision-making. At the same time the Association's extension specialist, together with the Government's cotton extension specialists, made monthly tours of the various cotton areas to hold cotton meetings which reviewed the trends of pest incidence so that an appropriate pest-control strategy could be-clearly defined. Growers estimated this service to be worth Z$20/ha. It is generally accepted that this has resulted in the Zimbabwe large-scale cotton grower becoming one of the most efficient in the world. In 1979 the Commercial Cotton Growers' Association (formerly Rhodesia Cotton Growers' Association) decided to assist the communal small-scale cotton producer by offering these farmers specialized cotton-production courses so that they, too, could take advantage of the expertise available to large-scale growers. This led to the development of the Cotton Training Centre which, when complete, will be able to provide residential training facilities for up to 300 students at a time, with a planned annual attendance of 4000 farmers on various cotton courses during any one year. Unlike the large-scale grower who, on average, grows 120 ha of cotton, the communal producer grows approximately 1 ha of cotton and so it is possible to offer pest-management services to individuals only if they are in groups or within a cooperative system. In order tO assess the feasibility of implementing various pest-management training programmes for communal producers, a large number of whom are illiterate, a pilot scheme was launched in 1980 before embarking on a large-scale training and service programme. The results of this pilot scheme indicated that a residential 3-week cotton-production course followed by weekly visits for 4 months during the growing season, could save the farmer up to four unnecessary pesticide applications and increase his yield by approximately 10~/o. This represents approximately 20~/o of the input cost.
250
Development of cotton-pest management in Zimbabwe
Special cotton-production courses f o r G o v e r n m e n t extension, as well as commercial, personnel are also held to ensure a unified approach to cotton extension and production methods over t h e whole country: over 330 small-scale producers participated in the 1981 cotton-production course and check scouting service. These farmers represented just over 180 groups or co-operatives comprising an estimated 3500 cotton producers or 8~o of the communal cotton production. T h e r e has been a very favourable response to these courses and demand is expected to double over the next 2 years. In 1963-64 the country produced 2778 t of lint. By 1982 this was increased to just over 70 000 t, making Zimbabwe the fourth largest producer in Africa. Over 75~o of Zimbabwe's cotton is exported: in 1981 this earned the country over Z$70 million in valuable foreign currency. It is hoped that, through the services and training provided by the Cotton Training Centre, Zimbabwe will continue to expand cotton production and maintain her reputation as one of the most efficient producers of high-quality cotton in the world. References BURGESS,M.W. (1971). Scouting is essential. Cotton Boll 1 (4), 22-23. GLEDHILL,J.A. (1976). Crop losses in cotton caused by Heliothis and Diparopsis bollworms. Rhodesia Agricultural Journal 73 (6), 135-138. MCKINSTRY,A.H. (1959). Cotton growingin Southern Rhodesia. Rhodesia Agricultural Journal 56 (4), 4. TUNSTALL,J.P. ANDMATTHEWS,G.A. (1965a). Recent advances in the control of cotton insect pests in the Rhodesias and Nyasaland. In: Proceedings of the Central African Scientific and Medical Congress, Lusaka, Northern Rhodesia, 26-30 August, 1963, pp. 522-527. Oxford: Pergamon Press. TUNSTALL,J.P. AND MATTHEWS,G.A. (1965b). Large-scale spraying trials for the control of cotton insect pests in Central Africa. Cotton Growing Review 43, 121-139. ZIMBABWECOMMERCIALCOTTONGROWERSASSOCIATION(1964). Cotton Handbook: a Rhodesian Farmer Publicat~'on. Zimbabwe: Kadoma (formerly Gatooma) Research Station. Looseleaf, 14 Sections.
Accepted 3 June 1982
Development of cotton-pest m a n a g e m e n t in Zimbabwe M. W. BURGESS
Cotton Training Centre, PO Box 530, Kadoma, Zimbabwe Use of insecticides on cotton is kept to a minimum in Zimbabwe by the recommendation that applications are timed on the basis of routine crop-inspection (scouting) data. Greater acceptance of field scouting by large-scale cotton producers was achieved by providing training for farm scouts. The syllabus for courses financed from a crop levy included recognition of insect pests and methods of recording their numbers. Subsequently, courses on data interpretation improved the timing of spraying, but scouting efficiency was increased most markedly by an on-farm check scouting scheme. Small-scale cotton farmers also are now provided with courses. Training schemes have been an important factor in the adoption of a pest-management programme. Cotton production has increased from less than 3000 t of lint in 1964 to over 70 000 t in 1982. ABSi"RACT.
Cotton was first grown commercially in Zimbabwe in 1924, but because effective chemical pest control was practically non-existent up to the late 1950s, cotton yields were variable and seldom exceeded 400 kg/ha seed cotton (McKinstry, 1959). Extension trials carried out in the 1960-61 and 1961-62 seasons (Tunstall and Matthews, 1965a,b) indicated that yield increases of up to 1500 kg/ha seed cotton were possible if the crop was sprayed regularly. T h e greatest response to spraying was obtained on crops provided with a high standard of crop husbandry. T h e main pests at that time were jassid (Empoasca facialis), heliothis bollworm (Heliothis armigera), red bollworm (Diparopsis castanea) and stainers (Dysdercus species). T h e large-scale commercial growers, who d i d p r o v i d e the requisite high standard of crop husbandry, were quick to see the advantage of this, and their Association published the first Cotton Handbook, in conjunction with Gatooma (now Kadoma) Research Station, in 1964 (Zimbabwe Commercial Cotton Growers Association, 1964). T h i s handbook has since become the standard cotton textbook for both growers and extension workers in Zimbabwe, and to a lesser extent in neighbouring countries. Over 75~o of Zimbabwe's cotton crop is rain grown and the seasonal variability of crop growth, pest incidence and the interaction of both, has made it extremely difficult to formulate simple recommendations for effective pest control while 0261-2194[83/02/0247-04503.00 © 1983 Butterworth & Co (Publishers) Ltd
248
Development of cotton-pest managementin Zimbabwe
avoiding unnecessary and potentially damaging spray applications which could be uneconomic as well as accelerating the build-up of resistance. Recommendations, therefore, depend upon considerable skill both in the collection of scouting (monitoring) data and in the interpretation of weekly scouting counts and their trends (Gledhill, 1976). This level of expertise has been possible only because the high standard of cotton research in Zimbabwe has been backed up by a most effective and well-trained extension service. As early as 1963 a specialist cotton advisory officer was posted to the Government Cotton Research Station at Kadoma (formerly Gatooma), initiating a successful arrangement between research and extension that has ensured already that farmers have had ready access to the results of latest research in all aspects of cotton production. This has contributed in no small way to the success of the cotton industry in Zimbabwe, which is illustrated by the fact that the average yield of seed Cotton on commercial cotton farms increased from 650 kg/ha to just under 1750 kg/ha during the period 1960-70. From the early 1960s, farmers were encouraged to spray their cotton on the basis of scouting results, but the majority still followed calendar schedules and even as late as 1971 it was still apparent that there were large variations in the number of applications that were used in similar pest situations (Burgess, 1971). Nevertheless, surveys carried out in 1971/72 indicated that commercial cotton growers were able to make substantial savings by employing trained cotton scouts and spraying only when pest damage thresholds were exceeded. It was clearly demonstrated that spraying on a calender schedule during the pre-bloom period of cotton growth was committing growers to up to Z$30/ha in chemical and application costs without any increase in yield, and in certain situations premature termination of spray programmes often resulted in serious bollworm damage to the top crop. In one case this was estimated at 20% of the total crop yield. Cotton extension objectives for commercial growers were redefined and intensive, specialized cotton training for farm scouts was started in 1972. In 1974 the then Rhodesia Cotton Growers' Association, which is financed from a self-imposed levy of 1"4~o of the value of growers' seed cotton, took over responsibility for these courses and initiated the development of the Cotton Production Training Unit at Kadoma in close co-operation with the Cotton Research Institute, also at Kadoma. The course syllabus included instruction in the recognition, life histories and feeding habits of the two key pests (Heliothis armigera and Diparopsis castanea) and of the two minor bollworm pests (Earias species and Pectinophora gossypiella) as well as eight sucking pests (Empoasca facialis, Aphis gossypii, Bemisia tabaci, Taylorilygus vosseleri, Helopeltis, Tetranychus, Thrips, Dysdercus and Oxycarenas species), several leaf-eating insects and five of the most commonly occurring predators (Chrysopa, coccinelid, syrphid, Phonoctonus and arachnid species). These courses also included methods of assessing field levels of these pests and of beneficial insects, based on scoUting a minimum of 24 average-sized plants on fields up to 20 ha in area. Methods of recording insect numbers, as well as the correct methods of application of insecticides and, to a lesser degree, methods of monitoring the effectiveness of aerial application, were included in the syllabus. Farmers were also encouraged to send their scouts on refresher courses during subsequent years to ensure that they were brought up to date in the latest techniques. In 1974, 641 farm employees were trained in cotton scouting methods~ By the end of 1977, 2819 people had received training on these courses and over 40% of the cotton grown by large-scale commercial farmers was being scouted regularly. However, it was
M. W. BURGESS
249
apparent from observations that there were two areas of weakness in the pest-management systems employed by many leading commercial farmers. The first was that the cotton scouts were not being adequately checked in the field and this was leading to inaccuracies in their data collection. The second area of weakness was in the farmer's interpretation of that data, which led to poor timing of pest-control operations. As a result, pilot schemes to check scouting were started in order to investigate the possibility of offering a comprehensive pest-management service to farmers to enable them to make better use of the latest recommendations and to maximize the profitability of cotton production. The result of these pilot schemes was the formation of an on-farm scouting and crop development recording service which, in 1978, involved over 180 farmers growing 22 000 ha of cotton. By 1980 nearly 30 000 ha were being regularly checked in this scheme, which represented approximatdy 25~o of the area under cotton in Zimbabwe and, according to surveys, was worth nearly Z$500 000 annually to the industry at an approximate cost to the farmers of Z$45 000. Farmers who joined the scheme were encouraged to attend pest-management courses at Kadoma and to employ at least two trained scouts. The Association, in turn, provided a team of trained scouts who were based throughout the country to visit scheme members once a week in order to check the farmer's scouting results. Any inaccuracies in data collection were quickly rectified. Scouting efficiency improved dramatically throughout the country as a result of this service, which cost the growers concerned Z$1/ha initially. Crop-monitoring records in the form of growth analysis were also collected, providing a back-up to identify possible causes of crop loss and assisting agronomic decision-making. At the same time the Association's extension specialist, together with the Government's cotton extension specialists, made monthly tours of the various cotton areas to hold cotton meetings which reviewed the trends of pest incidence so that an appropriate pest-control strategy could be-clearly defined. Growers estimated this service to be worth Z$20/ha. It is generally accepted that this has resulted in the Zimbabwe large-scale cotton grower becoming one of the most efficient in the world. In 1979 the Commercial Cotton Growers' Association (formerly Rhodesia Cotton Growers' Association) decided to assist the communal small-scale cotton producer by offering these farmers specialized cotton-production courses so that they, too, could take advantage of the expertise available to large-scale growers. This led to the development of the Cotton Training Centre which, when complete, will be able to provide residential training facilities for up to 300 students at a time, with a planned annual attendance of 4000 farmers on various cotton courses during any one year. Unlike the large-scale grower who, on average, grows 120 ha of cotton, the communal producer grows approximately 1 ha of cotton and so it is possible to offer pest-management services to individuals only if they are in groups or within a cooperative system. In order tO assess the feasibility of implementing various pest-management training programmes for communal producers, a large number of whom are illiterate, a pilot scheme was launched in 1980 before embarking on a large-scale training and service programme. The results of this pilot scheme indicated that a residential 3-week cotton-production course followed by weekly visits for 4 months during the growing season, could save the farmer up to four unnecessary pesticide applications and increase his yield by approximately 10~/o. This represents approximately 20~/o of the input cost.
250
Development of cotton-pest management in Zimbabwe
Special cotton-production courses f o r G o v e r n m e n t extension, as well as commercial, personnel are also held to ensure a unified approach to cotton extension and production methods over t h e whole country: over 330 small-scale producers participated in the 1981 cotton-production course and check scouting service. These farmers represented just over 180 groups or co-operatives comprising an estimated 3500 cotton producers or 8~o of the communal cotton production. T h e r e has been a very favourable response to these courses and demand is expected to double over the next 2 years. In 1963-64 the country produced 2778 t of lint. By 1982 this was increased to just over 70 000 t, making Zimbabwe the fourth largest producer in Africa. Over 75~o of Zimbabwe's cotton is exported: in 1981 this earned the country over Z$70 million in valuable foreign currency. It is hoped that, through the services and training provided by the Cotton Training Centre, Zimbabwe will continue to expand cotton production and maintain her reputation as one of the most efficient producers of high-quality cotton in the world. References BURGESS,M.W. (1971). Scouting is essential. Cotton Boll 1 (4), 22-23. GLEDHILL,J.A. (1976). Crop losses in cotton caused by Heliothis and Diparopsis bollworms. Rhodesia Agricultural Journal 73 (6), 135-138. MCKINSTRY,A.H. (1959). Cotton growingin Southern Rhodesia. Rhodesia Agricultural Journal 56 (4), 4. TUNSTALL,J.P. ANDMATTHEWS,G.A. (1965a). Recent advances in the control of cotton insect pests in the Rhodesias and Nyasaland. In: Proceedings of the Central African Scientific and Medical Congress, Lusaka, Northern Rhodesia, 26-30 August, 1963, pp. 522-527. Oxford: Pergamon Press. TUNSTALL,J.P. AND MATTHEWS,G.A. (1965b). Large-scale spraying trials for the control of cotton insect pests in Central Africa. Cotton Growing Review 43, 121-139. ZIMBABWECOMMERCIALCOTTONGROWERSASSOCIATION(1964). Cotton Handbook: a Rhodesian Farmer Publicat~'on. Zimbabwe: Kadoma (formerly Gatooma) Research Station. Looseleaf, 14 Sections.
Accepted 3 June 1982