The influence of some packaging and post-harvest treatments on the incidence of Ripe Spot in ‘Golden Delicious’ and ‘Crofton’ apples

Scientia Horticulturae, 3 (1975) 75--81 Elsevier Scientific Publishing Company, Amsterdam - - Printed in The Netherlands

THE INFLUENCE OF SOME PACKAGING A N D POST-HARVEST TREATMENTS ON THE INCIDENCE OF RIPE SPOT IN 'GOLDEN DELICIOUS' AND 'CROFTON' APPLES

J.B. O'LOUGHLIN

Tasmanian Department of Agriculture, New Town Research Laboratories, New Town, Tasmania (Australia) (Received February 26th, 1974)

ABSTRACT O'Loughlin, J.B., 1975. The influence of some packaging and post-harvest treatments on the incidence of Ripe Spot in 'Golden Delicious' and 'Crofton' apples. Scientia Hort., 3: 75--81. A trial was designed to study different methods of high humidity storage for bushel packs of apples. The methods studied were polyethylene (= polythene) bag liners (= polyliners), perforated polythene lined, together with the effectiveness of thiabendazole (T.B.Z.) in controlling Ripe Spot (Gloeosporium sp.) in polythene lined packs. A further treatment incorporated a wax coating on the apples instead of a polythene liner. A post-harvest dip of T.B.Z. followed by storage in polylined packs ensured that 'Golden Delicious' and 'Crofton' apples had minimal weight losses and low levels of Ripe Spot. Storage in polythene liner or perforated polythene liner without T.B.Z. resulted in high levels of Ripe Spot in both cultivars. Although waxing prior to storage did not increase the incidence of Ripe Spot over that in control fruit, it did not reduce weight loss to the low levels of the polylined treatments. INTRODUCTION

As costs of getting fruit to traditional markets in Great Britain and the European Continent have escalated, some orchardists have been considering ways of extending marketing within Australia by prolonging the storage life of apples, especially 'Golden Delicious' and 'Crofton'. The best way of doing this is to use controlled atmosphere (C.A.) storage. However, a reasonably low-cost alternative is to use polythene lined (polyliner) packs. The early research on polyliners by Gerhardt (1955) indicated the possibilities of extending the storage life of apples and pears. More recently the benefits from using low density 0.0375-mm polyethylene (polythene) liners for pears exported overseas from Tasmania have been described by the present author (O'Loughlin, 1967). 'Golden Delicious' apples can also be stored to advantage in polythene liners as they have a high weight loss with consequent shrivelling in conventional storage. In trials locally, Raphael (1966) found reduced weight losses in cases of polylined 'Golden Delicious' with approx. 3%

76 wastage from Ripe Spot (Gloeosporium sp.). He obtained similar results with bin liners for 'Golden Delicious' (Raphael, 1968). Since these trials there have been reports of significant wastage from Ripe Spot in commercial polylined 'Golden Delicious'. As stated by Padfield (1969), infection by Ripe Spot takes place in late summer while fruit is still on the trees. Apples picked at export maturity show little or no sign of the disease, but later pickings are likely to show a progressive increase in numbers of Ripe Spot lesions. On fruits, Ripe Spot lesions first appear as superficial pin-points, light to dark brown and slightly depressed. Normally lesions do not develop until apples are almost ripe enough to eat. Lesion colour tends to vary with the colour of the apple, being deep brown on red portions of the skin. On green-yellow areas, the lesions may have a pale brown or yellow centre with a darker brown margin. According to Atkinson (1971), when an efficient spray programme is followed by normal harvesting and rapid cool storage, losses from Ripe Spot are negligible. In the past, post-harvest fungal wastage of pome fruits has been of secondary importance to physiological disorders in stored pome fruits. However, in mainland Australia, the introduction of high humidity C.A. storage, water dumpers and pre-storage treatments with scald inhibitors have reduced the risk of physiological disorders and increased the dangers from the development of rots during storage. Thiabendazole (T.B.Z.) has been shown to control Blue Mould (Penicillium expansum), Grey Mould (Botrytis cinerea) and Target Rot (Gloeosporium album) in apples by workers such as Blanpied and Purnasiri (1970), Tugwell (1971) and Cargo and Dewey (1970). Beattie and Outhred (1970) found that wastage in pears inoculated with Penicillium expansum and Botrytis cinerea was significantly reduced when the fruit was dipped in aqueous formulations of T.B.Z. or benomyl. Ben-Arie and Guelfat-Reich (1973) reported similar findings with 'Spadona' pears together with an increase in the incidence of internal breakdown in pears with benzimidazole treatments. Many attempts have been made to retard transpiration and fruit metabolism by waxing and various skin coatings, e.g. Smock (1936, 1939), Trout et al. (1953). Farooqi and Hall (1973) reduced weight loss from 'Granny Smith' and 'Jonathan' apples by as much as 45% which was of the same order as found by Trout et al. (1953). Baghdadi and Smock (1943) compared plastic coverings with waxes for reducing moisture loss and found that 'Golden Delicious' in sealed pliofilm bags had 0.6% weight loss, whereas waxed 'Golden Delicious' had a weight loss of 5% after 6 weeks at 7°C and 75% R.H. The wax treatment was relatively ineffective in retarding ripening. The present trial was designed to study some different methods of high humidity storage, namely polylined, perforated polylined and waxed together with the effectiveness of T.B.Z. in controlling Ripe Spot in polylined packs.

77 METHOD 'Crofton' is a late keeping red apple, originated near Hobart and n o t grown widely outside Tasmania (Thomas, 1932). Samples of 'Crofton' and 'Golden Delicious' were obtained from blocks of trees in commercial orchards (Domeneys' at Woodbridge and Cart's at Grove) at t w o maturities. These samples were allocated at random to the following treatments, there being four replicates of each treatment: (1) Control. No polythene liner in standard apple case. (2) Waxed. As for (1) except fruit waxed before being placed in case. This involved dipping fruit in a 1 : 1 aqueous dilution of a commercial p r o d u c t (Primafresh 32@, S.C. Johnson & Son Pty. Ltd) containing 11.4% wax (mainly carnauba). (3) Polylined (Poly). Held in 0.0375-mm low density polythene bag liner in apple case. The t o p of the polythene bag was sealed by folding excess polythene across the t o p of the b o x from each side. (4) Polylined + thiabendazole (T.B.Z.). As for (3) except fruit dipped in 2 000 p p m T.B.Z. for 2 min and then dried in front of a heater before being placed inside a polythene liner. (5) Perforated polylined (P. Poly). As for (3) except the polythene liner had ten 3-mm diameter holes. The 'Golden Delicious' samples were harvested from each grower on March 23rd and April 14th. The 'Crofton' samples were harvested at Carr's on April 27th and May 6th and at D o m e n e y s ' on May 5th and May 13th. All samples were placed in cool store within 48 h of harvest and held at 1--2 ° C until October 16th. They were then transferred to constant temperature rooms held at approx. 18°C to simulate conditions on Brisbane and Sydney markets. A first examination was made after 10 days ex store followed by a second examination after another 9 days. At these examinations, weight loss and ground colour as well as wastage from Ripe Spot and other disorders were recorded. For each of the four cultivar grower combinations a split plot analysis of variance was performed with the treatments listed above as main plots and harvest times as sub plots. RESULTS The information obtained for each treatment for 'Golden Delicious' and 'Crofton' has been summarised in Tables I and II respectively. Significant interactions between harvest date and treatment occurred in half of the 18 observations made. The relationship between treatments with respect to percentage weight loss was reasonably uniform over all cultivar/grower combinations. Where treatment means in Tables I and II could be compared, the polylined, perforated polylined and T.B.Z. treatments did n o t differ significantly from

78

TABLE I S u m m a r y o f observations o n ' G o l d e n Delicious' for each t r e a t m e n t . N.A. : n o t applicable d u e to t r e a t m e n t a n d harvest interaction Grower

Observation

Treatment

L.S.D.

Control

P. Poly

Domeney Domeney Domeney Domeney Domeney Domeney Domeney

% weight loss % Ripe Spot (1st e x a m . ) % Ripe S p o t ( 2 n d e x a m . ) % Ripe S p o t (total) % Breakdown G r o u n d colour (harv. I ) G r o u n d colour (hare. 2)

8.79 9.66 4.40 14.06 2.01 YY YY

1.60 40.61 16.03 56.64 5.05 Y YY

Cart Cart Carr Cart Cart Cart

% weight loss % Ripe S p o t ( l s t e x a m . ) % Ripe Spot ( 2 n d e x a m . ) % Ripe Spot (total) G r o u n d colour (harv. I ) G r o u n d colour (hare. 2)

8.07 33.00 4.17 37.17 GYY Y

2.17 80.22 5.65 85.87 GYY Y

Poly

T.B.Z.

1.08 0.81 17.96 0.75 9.29 0.38 27.25 1.13 5.65 8.96 GYY-YGYY-Y Y ~/ 1.30 54.58 10.32 64.90 GGY GYY

1.07 2.33 1.33 3.67 GGY GY

Waxed

P = 0.05

7.44 7.38 3.25 10.63 2.00 y y.yy

N.A. N.A. N.A. N.A. N.A. ---

6.68 16.68 3.00 19.68 GYY y

1.38 6.67 N.A. 8.11 ---

T A B L E II S u m m a r y o f observations o n ' C r o f t o n ' for each t r e a t m e n t . N.A. : n o t applicable d u e to t r e a t m e n t a n d harvest interaction; N.S. : n o t statistically significant. Grower

Observation

Treatment

L.S.D.

Control

P. Poly

Poly

0.93 31.00 12.88 43.88 1.13 GY GY

0.36 20.85 11.36 32.21 0.75 GGY GGY-GY

Domeney Domeney Domeney Domeney Domeney Domeney Domeney

% weight loss % Ripe Spot ( l s t e x a m . ) % Ripe Spot ( 2 n d e x a m . ) % Ripe S p o t (total) % Breakdown Ground colour (harv.l) G r o u n d colour (hare.2)

5.49 8.13 4.38 12.50 0.63 GY GY

Cart Carr Cart Carr Cart Cart

% weight loss % Ripe Spot (1st e x a m . ) % Ripe Spot ( 2 n d e x a m . ) % Ripe Spot (total) G r o u n d colour ( h a r e . l ) G r o u n d colour (hare.2)

6.10 4.75 1.13 5.88 GY GY

T.B.Z. 0.49 1.13 1.86 2.99 0.61 GGY GGY

Waxed 4.58 10.25 3.63 13.88 0.63 GGY-GY GGY-GY

1.23 0.43 1.53 5.64 16.63 10.56 0.13 4.13 5.53 5.33 0.88 0.88 22.15 15.89 1.00 5.00 GGY-GY G G Y G G Y GGY-GY GY G G Y - G Y G G Y - G Y G G Y - G Y

P=0.05 N.A. N.A. 2.74 I~.A. N.S. --1.32 4.70 2.07 5.15 ---

each other and gave large and significant reductions compared with the control and waxed treatments. Weight loss in the 'Golden Delicious' samples was considerably higher than for 'Crofton'. Although the incidence of Ripe Spot was relatively low in 'Crofton' from grower Cart, the treatments were in the same order as for other cultivar/grower

79 c o m b i n a t i o n s . If t h e ' C r o f t o n ' harvest dates h a d b e e n t h e same as f o r g r o w e r D o m e n e y , h i g h e r levels o f Ripe S p o t m a y have b e e n r e c o r d e d , as D o m e n e y s ' first harvest was o n l y 1 d a y earlier t h a n Cart's s e c o n d harvest. T h e a m o u n t o f Ripe S p o t r e c o r d e d at each e x a m i n a t i o n has b e e n p r e s e n t e d in Tables I a n d II since a l t h o u g h t h e m a j o r p o r t i o n was o b s e r v e d a f t e r 10 days at 1 8 ° C t h e r e was a f u r t h e r increase in t h e f o l l o w i n g 9 days. Analysis o f the p e r c e n t a g e Ripe S p o t a f t e r 10 days gave similar t r e a t m e n t c o m p a r i s o n s as f o r t h e t o t a l figures. Considering t h e p e r c e n t a g e b r e a k d o w n in ' G o l d e n Delicious' f r o m D o m e n e y , t h e p o l y l i n e d and T.B.Z. t r e a t m e n t s were significantly h i g h e r t h a n the c o n t r o l at t h e s e c o n d harvest o n l y with t h e T.B.Z. t r e a t m e n t significantly higher t h a n t h e p o l y l i n e d t r e a t m e n t . TABLE III Summary of observations on 'Golden Delicious' for each harvest. N.A. : not applicable due to treatment and harvest interaction; N.S.: not statistically significant Grower

Observation

Harvest

L.S.D.

1

2

P= 0.05

Domeney Domeney Domeney Domeney Domeney

% Weight loss % Ripe Spot (lst. exam.) % Ripe Spot (2rid exam.) % Ripe Spot (total) % Breakdown

4.28 12.87 4.26 17.12 2.95

3.61 17.68 9.08 26.76 6.53

N.A. N.A. N.A. N.A. N.A.

Cart Cart Cart Cart

% % % %

3.75 33.45 3.86 37.31

3.99 41.28 5.93 47.21

N.S. 5.63 N.A. 5.58

Weight loss Ripe Spot (1st exam.) Ripe Spot (2nd exam.) Ripe Spot (total)

TABLE IV Summary of observations on 'Crofton' for each harvest. N.A.: not applicable due to treatment and harvest interaction; N.S. : not statistically significant Grower

Observation

Harvest

1 Domeney Domeney Domeney Domeney Domeney

% Weight loss % Ripe Spot ( l s t exam.)

Carr Cart Carr Cart

L.S.D.

2

P=0.05

2.18

2.56

% Ripe Spot (2nd exam.) % Ripe Spot (total) % Breakdown

8.06 5.55 13.61 0.25

20.48 8.09 28.57 1.25

% Weight loss % Ripe Spot (lst exam.) % Ripe Spot (2nd exam.) % Ripe Spot (total)

3.20 5.28 2.48 7.76

2.77 9.20 3.01 12.21

N.A. N.A.

2.13 N.A. 0.61 N.S. 2.14 N.S. 1.87

80

The influence of harvest date on each observation is summarised in Tables III and IV. The late harvest for each cultivar/grower/examination combination had higher levels of Ripe Spot although not all these differences were statistically significant. Similarly the late harvest increased the level of breakdown in 'Crofton' and 'Golden Delicious' from Domeney. Breakdown was not recorded in samples from grower Carr. DISCUSSION

The percentage weight loss figures show that the waxed treatment was not an effective method for high humidity (and low weight loss) storage when compared with polylined treatments. This is in agreement with the conclusions of Baghdadi and Smock (1943). The information obtained for weight losses in the three polyliner treatments (polyliner, perforated polyliner and T.B.Z.) confirmed earlier studies such as those by Raphael (1966 and 1968). The T.B.Z. treatment had the lowest incidence of Ripe Spot, being significantly lower than the control in most cultivar/grower/examination combinations. In all four cultivar/grower combinations for total Ripe Spot the T.B.Z. treatment was lower than the control fruit. The T.B.Z. treatment always gave a large and significant reduction in Ripe Spot when compared with the other two polyliner treatments. In other words, the T.B.Z. treatment combined the low weight loss of the other polyliner treatments with even less wastage from Ripe Spot than in control fruit. The relatively high levels of Ripe Spot in the other polyliner treatments did not agree with the earlier work by Raphael (1966 and 1968), thereby suggesting that other factors such as harvest date, spray programme, orchard locality and length of storage influence the levels of Ripe Spot. The relatively low incidence of Ripe Spot in 'Crofton' from Cart would support this view. The second harvest of 'Crofton' from Cart's orchard was only 1 day later than the first harvest from Domeneys' orchard. Both had similar levels of Ripe Spot. A feature of treatment comparisons was that the perforated polythene treatment had higher levels (mostly significant) of Ripe Spot than the polyliner treatment. This would probably be due to the more advanced maturity of fruit (see ground colour observations) in perforated polythene since there would not be a build up of carbon dioxide to retard maturity as in entire polylined packs. Although there were higher levels of Ripe Spot in the late harvest samples, the increase was not as great as expected. This would suggest that the high humidity conditions in polythene bags had a greater influence. Although neither cultivar studied is very susceptible to breakdown, it was interesting to note its significant increase in the T.B.Z. treatment in the second harvest of 'Golden Delicious' from Domeney in view of the findings of BenArie and Guelfat-Reich (1973). This could be clarified by studying a cultivar such as 'Jonathan' or 'Delicious' which is susceptible to breakdown.

81 ACKNOWLEDGEMENTS

The author appreciated the co-operation of Messrs D. and E. D o m e n e y and Mr H.V. Cart from whose orchards samples were obtained. Special thanks are due to Mr P.F. Meure w h o assisted with all stages of the trial and Messrs Gillis and Zantuck who assisted with the analysis of the results. REFERENCES Atkinson, J.D., 1971. Diseases of Tree Fruits in New Zealand. D.S.I.R. Inf. Ser. 8 1 , 4 0 6 pp. Baghdadi, H.A. and Smock, R.M., 1943. The comparative value of certain plastic materials and waxes in checking moisture loss from apples. Proc. Am. Soc. Hort. Sci., 42: 238-245 Beattie, B.B. and Outhred, N.L., 1970. Benzimidazole derivatives as post harvest fungicides to control rotting of pears, cherries and apricots. Aust. J. Exp. Agric. Anita. Husb., 10: 651--656 Ben-Arie, R. and Guelfat-Reich, S., 1973. Preharvest and post harvest applications of Benzimidazoles for control of storage decay of pears. Hort Science, 8 : 1 8 1 - - 1 8 3 Blanpied, G.D. and Purnasiri, A., 1970. Thiabendazole control of post harvest apple decay. Hort Science, 5 : 4 7 6 - - 4 7 8 Cargo, C.A. and Dewey, P.H., 1970. Thiabendazole and Benomyl for the control of postharvest decay of apples. Hort Science, 5 : 2 5 9 - - 2 6 0 Farooqi, W.A. and Hall, E.G., 1973. Effect of wax coatings containing diphenylamine on apples and pears during storage and ripening. Aust. J. Exp. Agric. Anita. Husb., 13: 200--204 Gerhardt, F., 1955. The Use of Film Box Liners to Extend Storage Life of Pears and Apples. U.S. Dept. Agric. Circ. No. 955, 28 pp. O'Loughlin, J.B., 1967. Polythene liners for pears. Tasm. J. Agric., 3 8 : 8 1 - - 8 3 Padfield, C.A.S., 1969. The Storage of Apples and Pears. N.Z.D.S.I.R. Bull., 117 pp. Raphael, T.D., 1966. Case liners for Golden Delicious apples. Tasm. J. Agric., 3 7 : 5 2 - - 5 4 Raphael, T.D., 1968. Bin liners for Golden Delicious apples. Tasm. J. Agric., 3 9 : 2 7 - - 2 9 Smock, R.M., 1936. Certain effects of wax treatments on various varieties of apples and pears. Proc. Am. Soc. Hort. Sci., 3 3 : 2 8 4 - - 2 8 9 Smock, R.M., 1939. Some additional effects of waxing apples. Proc. Am. Soc. Hort. Sci., 37:448--452 Thomas, P.H., 1932. Apple varieties raised in Tasmania (4) The Crofton. Tasm. J. Agric., 3: 131--133 Trout, S.A., Hall, E.G. and Sykes, S.M., 1953. Effects of skin coatings on the behaviour of apples in storage. Aust. J. Agric. Res., 4 : 5 7 - - 8 1 Tugwell, B.L., 1971. The post harvest treatment of pome fruits with thiabendazole for mould control during storage and transport. S. Aust. Dept. Agric. Rep., 2/71