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10rots, packinghouses are designed with wallsseparating the input and output ends of thepacking lines. The fruit packing operation isphysically separated from the part of the linewhere bins are emptied and decayed fruit areremoved. The physical separation keeps sporesfrom the “dirty” part of the packing line fromblowing into the area where fruit are beingpacked.Putting a wall through the middle of theapple packing line will be impractical in mostsituations. However, air flow patterns andlocations of exhaust fans might be adjusted tominimize the movement of air from the waterdump area toward the area where fruit arepacked.What About Fungicide Alternatives?Captan used in postharvest treatments mightprevent P. expansum from invading stems inEmpire fruit. Captan has never been veryeffective for protecting against postharvestdecays in wounds, but there is some evidencethat it may be adequate for protecting stems.More tests are currently in progress. Wherecaptan-treated fruit are acceptable to buyers,using captan in postharvest drenches might helpto reduce decay in Empire fruit as compared tousing only DPA plus Mertect 340F. However,avoiding all postharvest treatments on Empirefruit is still likely to be the best option.Several biocontrol fungicides have beenregistered for postharvest use on apples, but theyare either ineffective or unavailable due todistribution and marketing problems. In somecases, these products are only registered for useas line sprays and they therefore cannot be usedin drenches prior to CA storage.Novartis has a new fungicide with the tradename of “Scholar” that could prove useful as apostharvest treatment for apples. The genericname for Scholar is fludioxonil. It is aphenylpyrrole fungicide with a different mode ofaction than any of the other fungicides currentlyregistered for field or postharvest use on apples.Scholar has been very effective against P.expansum in several trials conducted at theHudson Valley Lab, but it probably will requireat least two more years of testing before it can beregistered.Even if Scholar or some other new fungicideis eventually registered for apples, resistance tothe new fungicide will develop quickly unlessinoculum levels are kept to a minimum. Thecombination of DPA and benzimidazolefungicides remained effective for nearly 20 yearsonly because of a fortuitous interaction betweenDPA and the fungicides that sloweddevelopment of resistance. In the absence ofDPA, the benzimidazoles would have controlledpostharvest decays for only about five years, anda similar fate can be anticipated for any othernew fungicides that might be introduced unlessthe new product is managed carefully to forestallresistance.ConclusionsImproved sanitation will be essential forminimizing losses during CA storage, forreducing the incidence of decayed fruit inconsumer packages, and for preventing rapiddevelopment of fungicide resistant strains thatwould compromise any new fungicide that mightbe introduced. Basic sanitation measures thatshould be implemented immediately include thefollowing:1. Chlorinate water flumes in packing houses.2. Do not apply postharvest fungicide/DPAtreatments unless absolutely necessary.3. Look for improved ways to sanitize floorsand surfaces in packinghouses and toeliminate inoculum from contaminated bins.
11ReTain effects during storage of Empire applesLast year we reported on CA storage ofMcIntosh fruit which had been untreated ortreated with ReTain before harvest. In general,our results indicated that while effects of ReTainon fruit maturity, especially internal ethyleneconcentration, could be significant, nodifferences in storage quality were detected. Inthe1999 harvest season we carried out a similarexperiment using Empire, a variety that producesless ethylene than McIntosh. Fruit wereharvested from four Western New York orchardson two occasions. Fruit maturity was assessed onfruit from each orchard and then fruit from eachorchard were stored under CA conditions (2%O 2 /2% CO 2 ) at 36 o F. Untreated and ReTaintreatedfruit were stored separately, but for thefirst harvest date, separate CA chambers withmixed-treatments were also established. ReTaintreatedand untreated fruit were mixed in thesame chamber to determine if ethyleneproductionfrom the non-treated fruit wouldcompromise the potential storage-enhancementthat might be provided if Retain-treated fruitwere never exposed to untreated fruit that weregenerating ethylene.At the first harvest date, fruit fromuntreated trees in two orchards had high internalethylene, but ReTain treatment prevented thisincrease (Table 4). By the second harvest onOctober 7, however, ReTain only controlledethylene in orchard 4.Fruit were removed from storage after 5months and quality evaluated after 1 and 7 daysat 68 o F. ReTain-treated fruit were firmer thancontrol fruit overall, but averaged only 0.3 lbgreater firmness over both harvest dates. Becausetreatment effects for 1 and 7 days shelf life werethe same, only data for 1 day of shelf life areshown (Table 5). These show that the responseto ReTain during storage was greatly affected byorchard. There was no significant effect oftreatment for orchards 1 to 3, but ReTain-treatedfruit from orchard 4 was 0.9 lb firmer than theuntreated fruit. The firmness benefit for fruitfrom this orchard was found at both harvests.Interestingly, orchard 4 had the most soft fruit atharvest (Table 4).Untreated fruit had similar firmness oneither day 1 or day 7, regardless of whether fruitwere stored separately or with ReTain-treatedfruit (Table 6). ReTain-treated fruit, however,were slightly firmer when stored with othertreated fruit than with untreated fruit on day 1,but not on day 7.Our conclusions are that ReTaintreatment may result in significant maintenanceof firmness, especially in fruit from an earlymaturing block. However, these effects areorchard-specific and inconsistent. In general,ReTain should be used as a harvest managementtool rather than a means of maintaining qualityduring storage.Table 4 Internal ethylene concentrations (ppm) and flesh firmness (lb) of untreated or ReTain-treatedEmpire fruit from four Western New York orchards harvested on two occasions.Harvest date Orchard Internal ethylene concentration Flesh firmness (lb)number(ppm)Untreated ReTain-treated Control ReTain-treated9/28/99 1 3.77 0.22 17.7 17.82 0.17 0.15 18.1 17.83 17.04 0.26 18.0 18.34 0.14 0.13 17.2 17.510/7/99 1 4.55 15.27 14.0 14.22 0.72 2.61 14.2 14.53 6.91 6.73 14.2 13.84 5.70 0.19 13.5 14.3
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