ORGANIC AND LOW-SPRAY                      800-346-9140                                                                   ...
A note on terms:                           •   Cultural guidelines for controlling one pest                               ...
Appendix 4. Some Eastern growers using the             packed into 1- or 5-ounce bags for sale. “Weapproach outlined in th...
The oblique banded leafroller, a particularlypersistent pest, takes “a lot of scouting” and well-           •   Internal d...
pheromone trap that can capture the insects as                      Table 1: Detecting Plum Curculio in the Orchard (7)   ...
Orchard establishment  “Because of plum curculio’s preference for maple woodlots as overwintering sites and its low winter...
Seasonal history of plum curculio (USDA)successful organic orchard he’s visited “had            Among the most promising n...
worse if pheromone levels drop low enough to          the eggs hatch, the larvae will quickly enter aallow mating to occur...
ATTRACTING AND CONSERVING BENEFICIAL INSECTS  “Farmscaping” is the use of hedgerows, insectary plants, cover crops, and wa...
soil, and certain weed stems. Wrap the trunks       Like the plum curculio and the codling moth, thewith corrugated cardbo...
Non-selective pesticidesthose that affect                  through early May, and begin laying eggsbeneficial and pest or...
one inch of the soil should inhibit the                   safe—and thus exempt from requirements of adevelopment of burr k...
the researcher terms “suppression” in these          orchard have shown over 90% control of theUSDA trials is very close t...
says, “I don’t believe organics should be food only        Understanding genetic disease resistancefor rich people. Our ap...
Table 2: Approximate number of hours of continued wet foliage required for        primary apple scab infection at differen...
is sufficiently long at the existing temperature to          blotch, black rot, bitter rot, and white rot (moreproduce an ...
spread. Affected branches wither and turn black                                                                SUMMER CUTS...
A promising biocontrol technique employing                                                         Fire blight development...
orange gelatinous “horns” on the galls on the             Little attention has been given in university trialscedar. This ...
Williams Pride, Pristine, and Priscilla, generallyEd Fackler (42), an Indiana low-spray orchardist,    escape sooty blotch...
further divided by size into dwarf, semi-dwarf,       Matching the right rootstock to the growersand semi-standard.       ...
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
Organic and Low-Spray Apple Production
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  1. 1. ORGANIC AND LOW-SPRAY 800-346-9140 APPLE PRODUCTION Appr i e Technol Tr opr at ogy ansf f Rur Ar er or al eas HORTICULTURE PRODUCTION ATTRA is the national sustainable agriculture information center funded by the USDA’s Rural Business -- Cooperative Service.Abstract: This publication surveys information appropriate to organic and low-spray apple production, drawing onrecent research and producer experience. Many aspects of apple production will be the same whether the grower useslow-spray, organic or conventional management. Accordingly, this publication focuses on the aspects that differ fromconventional practiceprimarily pest and disease control. (Information on organic weed control and fertilitymanagement is presented in a separate ATTRA publication, Overview of Organic Fruit Production.) The majorinsect pests and diseases are covered, and the most effective low-spray and organic control methods are introduced.Also included are three profiles of working orchards, and a section dealing with economic considerations. There arefour appendices: a list of resources for information and supplies, a chart of disease-resistant apple varieties, an articleexplaining the use of degree days in codling moth management, and a profile of a successful low-spray program.By Richard Earles, Guy Ames, RadhikaBalasubrahmanyam, and Holly Born,NCAT Agriculture SpecialistsOctober 1999INTRODUCTIONAt least two key insect pests, several seriousdiseases, and high cosmetic standards for freshmarket fruit present formidable obstacles toorganic or low-spray apple production.Moreover, recent “food scares” involving applejuice, and subsequent regulatory actions, threatenan important value-added component of low-spray and organic operations, which often have arelatively high percent of juice apples.Nevertheless, with disease-resistant cultivars and common pest and disease problems and pointcareful management, growers can greatly toward some alternative control strategies thatreduceand in some cases eliminatetheir have been effective. Not all of these methods willreliance on synthetic pesticides. be appropriate for every orchard or every region.As this publication is written for national In other words, the following is a set of guidelines,distribution, it can only introduce the most not a list of prescriptions. Geographical/climatic considerations, cultivar selection, the local pest complex, market prices, production costs, and Contents: Geographical factors.......................................... 2 other factors will all influence the design and Insect & mite pests.............................................. 4 viability of a commercial organic or low-spray Kaolin clay........................................................... 12 system. Reducing chemical input and foregoing Diseases ................................................................. 14 conventional calendar spray schedules will require Mammal & bird pests ........................................ 21 the orchardist to develop an understanding of the Economics & marketing .................................... 22 References............................................................. 25 orchard agro-ecosystem. In this regard, there is no Appendices ........................................................... 27 substitute for direct observation and experience, along with a willingness to experiment. IS A PROJECT OF THE NATIONAL CENTER FOR APPROPRIATE TECHNOLOGY
  2. 2. A note on terms: • Cultural guidelines for controlling one pest may create conditions that favor another pest; The term low-spray has no precise definition • Many ecological pest control tactics tend to and simply refers to a reduced synthetic give highly variable results from location to pesticide spray program relative to an areas location and year to year; prevailing or conventional spray programs. • Traditional local support services are often The word organic has precise legal definitions unable to provide much information or in many states, and certification groups guidance; maintain standards for what can be marketed • Available ecological practices may be labor- as “organically grown.” The USDA is currently and/or capital-intensive. (2). attempting to implement a national set of standards. Refer to the ATTRA publication Organic Certification for an in-depth discussion GEOGRAPHICAL FACTORS AFFECTING of this topic. In general, it can be said that “organic” refers to growing methods that DISEASE AND PEST INCIDENCE utilize only naturally occurring substances or organisms for fertility management and pest West of the “tree line” (approximately the 97th and disease control. meridian; a line roughly running from Ft. Worth, TX, to Fargo, ND), a major pest of many treeLow-spray and organic apple production systems fruitsthe plum curculiois not present. Thisare information-dependent, and the orchardist fact, coupled with reduced disease pressure,should not underestimate the value of keeping facilitates the organic production of apples inup with research in this rapidly changing field. much of the West.Internationally, researchers and producers areworking to craft and implement advanced Eastern growers must contend with the plumIntegrated Pest Management (IPM) programs curculio and increased incidence of fungalthat use a minimum of synthetic chemicals, seek diseases. Northeastern growers have the appleleast-toxic alternatives, maggot as anand utilize biological and additional majorcultural controls. The pest. In theATTRA publication Southeast, fruitIntegrated Pest Management rots can beprovides a good especiallyintroduction to IPM troublesome.principles and practices. Commercial-For an overview of the scale organichistory and current state production ofof IPM disease apples in themanagement in apples, East is very A well laid-out young orchard, Pacific Northwestand an example of an problematic,advanced IPM program that reduced fungicide mostly due to the presence of the plum curculio.use by 34% while retaining conventional levels of Organic growers should plan for no more thandisease control, see the academic article cited as 60−70% fresh market fruit from any harvest. Thereference (1). remainder will have to be culled for processing or discarded. Research and experience indicate thatWhat may begin as a fragmented, pest-by-pest set without some form of insect control more thanof tactics should gradually be integrated into an 90% of an apple crop will suffer insect damage (3).overall management plan in which the various Eastern commercial-scale growers seeking tostrategies work together as much as possible. reduce pesticide sprays should study the articleObstacles to a holistic or integrated approach “Very Low-Spray Apple Growing,” included asinclude the following: // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 2
  3. 3. Appendix 4. Some Eastern growers using the packed into 1- or 5-ounce bags for sale. “Weapproach outlined in that article have reduced don’t receive a premium, at least not as yet,” saystheir synthetic pesticide treatments to two Judy, “but we do make a profit.”insecticide sprays for the curculio and achieved90% or better fresh-market quality fruit. Apple scab, their most serious disease problem, is controlled by carefully timed applications ofFARMER PROFILE: EBDC (ethylene bisdithiocarbamate) contactSteven Clarke, Milton, New York fungicides like Mancozeb, Penncozeb and Polyram. EBDC fungicides offer broad spectrumIf Steven Clarke were asked to name the three control and are used mainly for foliar diseasefactors absolutely vital to the success of an IPM- management. “We may spray the same numberbased orchard, he would say, “Timing, timing, of times as conventional growers,” says Steve,timing.” Clarke, who runs Prospect Hill “but we use half the amount they do.” FollowingOrchards in New York’s Hudson Valley with his late winter pruning, he runs through the orchardwife Judy, their daughter Pam and son Brad, has with a sweeper, gathering the brush and thebeen in the fruit business for 30 years. The family leaves and grinding them up with a hammerfarm was started in 1817 by Steve’s great-great- knife mower. The chipping and grinding shattergreat-grandfather. Ten years ago they made the the leaves and help to reduce the overwinteringswitch to IPM, and their apples, now marketed inoculum in spring.through local fruit stands and a U-Pick, and atfarmers’ markets in New York City, bear the Powdery mildew, which sets in right after bloom,CORE Values Northeast seal, a regional eco-label is usually controlled by three applications ofthat guarantees the fruit has been raised using Bayleton at the rate of 2 oz/acre. This year,ecologically responsible IPM methods. Clarke plans to switch to sulfur, a less expensive option. Quince rust and apple cedar rust are twoThe shift to IPM has meant a reduction in other fungal diseases that occur between pinkpesticide use and a perceptible increase in and one week after petal fall. Both are wellbeneficial insect populations in the controlled by the EBDC’s and are not a problem,orchardmore syrphid flies, more ladybugs, says Clarke.fewer aphids. Judy says that they’ve alsoobserved more fly speck and sooty blotch, Abandoned orchards in the surrounding area arediseases that scar the fruit surface but do no harm a persistent source of insect pests. Plum curculioto the fruit. She attributes the incidence of these activity is triggered by the first warm night of thediseases to the minimal spray program used on season after bloom, Clarke observes, when itthe farm, adding that the blemishes can begins its migration into his orchard. At thissometimes constitute a marketing challenge. time, he sprays the edge of the orchard with“Consumers are generally willing to tolerate a Guthion. Ten days later, he follows this up withcertain number of marks on the fruit,” she says, an orchard-wide spray. If this is followed by cool“We do some general education. Some people weather, which the curculio likes, he may have towalk away when they hear that the apples are spray the border once more.not organic, but the majority of people stop tolisten.” Red sticky spheres (see section on apple maggots below) serve to signal the emergence of adultThe Clarkes raise 25 varieties of apples, including apple maggot flies. To control the flies ClarkeRed and Golden Delicious, Macintosh, Empire, uses a single spray around the time of emergence,Mutsu, Rome, McCoun and Gala. Ninety percent usually after the 4th of July. Late-yieldingof the crop is picked into 20-bushel bins and sold varieties may get another pesticide applicationwholesale to local fruit stands. The rest is sold by later in the season. Predatory mites (T. pyri)Pam at open-air farmers’ markets in New York released in the orchard control red or by Judy through the U-pick. A small part Dormant oil helps to destroy red mite eggs and, ifof the crop is processed into jam or dried and applied early enough, also controls San Jose scale. // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 3
  4. 4. The oblique banded leafroller, a particularlypersistent pest, takes “a lot of scouting” and well- • Internal damage from burrowing larvae;timed sprays of Bt, sometimes Lorsban, to • Premature fruit drop (“June drops”);control.Clarke uses no compost but makessupplemental, precision applications ofpotash and nitrogen. Round Up is thepreferred option for weed controlbecause it is a contact herbicide andleaves no residue. Foliar applications ofmicronutrients such as zinc and boron atpink, and calcium and magnesiumduring the growing season, haveimproved yields. Annual outputaverages 35,000 bushels, with 80 acres inproduction at any given time. As anexperiment, Clarke plans to set asidefive acres of trees for organic production.Here, he will use disease-resistantvarieties and organic techniques to The plum curculio, Conotrachelus nenuphar. Adult above at left; larvamitigate insect and disease pressure. below at left; pupa at right, ventral view. About 8 times natural size. (From Ill. Natural History Survey.)For information, contact Steven, Pam and • Puncturing by adults feeding in late summerJudy Clarke, Prospect Hill Orchards, 40 and fall.Clarke’s Lane, Milton NY. Phone: 914-795-2383.E-mail: The adult weevils overwinter in woodlots, fence rows, and hedges, and move into the orchard during bloom to feed on young flowers. AfterINSECT AND MITE PESTS mating, the female bores a small hole in the skin of a developing fruit, deposits a single egg, andPlum curculio then makes a crescent cut below the hole to protect the egg from being crushed by the rapidly “It is the considered opinion of entomologists expanding fruit tissue. The female lays an that plum curculios, not gravity, cause apples average of 150 to 200 eggs, which hatch 2 to 12 to fall.”May Berenbaum (4) days later. The grub tunnels into the fruit’s central seed cavity where it feeds until it has “It has been written that there are no organic completed its developmentabout three weeks. eating apples (as opposed to juice/vinegar Then it generates and releases pectin enzymes apples) grown in Massachusetts, and that this that “trick” the host fruit into dropping pest is the barrier preventing such in the prematurely, eats its way out of the fallen fruit, Northeast.”Ralph DeGregorio (5) and enters the soil to pupate (4).The plum curculio (Contrachelus nenuphar), a Biological monitoringsystematically scoutingsmall brownish weevil, has been the Achilles heel the orchard to detect the presence or measure theof organic apple production in the eastern U.S.. population density of pestsprovides criticalThis species of snout beetle injures fruit in several information for choosing and timing controlways: strategies. Monitoring is more difficult and more labor-intensive for the plum curculio than for• Scarring from surface feeding and oviposition other insects. USDA Agricultural Research (egg depositing); Service (ARS) scientists have patented a // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 4
  5. 5. pheromone trap that can capture the insects as Table 1: Detecting Plum Curculio in the Orchard (7) STAGE TIMING WHERE TO LOOK Adults Spring when temperatures In orchard adjacent to hedgerow. Feeding exceed 60°F (15.5°C) wounds are frequently the first sign of adult presence. Adults Late July to hibernation Same as above (temps. Below 60°F (15.5°C) Eggs Petal fall and 30 days On developing fruit within crescent shaped thereafter oviposition wounds Larvae Early June through mid-July Within injured, dropped fruit. Pupae Mid-July through mid-August In soil within 25mm (1 in.) of surfacethey first arrive in the orchard, giving thegrower an early warning. Until this technology treatments with rotenone are detrimental tois available commercially, visual observation of beneficial insects and other non-target organisms.adults and their crescent-shaped oviposition In fact, most certification programs restrict ormarks remains the best mode of detection. prohibit the use of rotenone in organic productionSince the PC enters the orchard from because it is a broad-spectrum pesticide.surrounding habitat such as woodlots, it isimportant to check the fruit on perimeter apple A combination of several cultural controltrees at bloom. Plum trees planted as “trap methods can be helpful against the plumtrees” could serve as early detectors, since the curculio; however, none provides a level ofcrescent signature appears earlier on the plum control comparable to that achieved withfruit than on the apple (6). According to Dr. chemicals. Since fruit infested with PC larvaeRon Prokopy (8), anentomologist at the typically drop before the larvae complete theirUniversity of Massachusetts and a small-scale feeding, prompt gathering and disposal of thecommercial orchardist, an effective, organically “drops”beforeacceptable control for the plum curculio does the larvae leavenot exist (though a revolutionary non-synthetic them to enter thespray may well change that. See Kaolin clay, soilreduces thebelow.) Prokopy has achieved control with number of first2−3 sprays (the first at petal fall and the generationremainder at 10−14 day intervals) of the adults. Thesynthetic pesticide Imidan. infested drops should beUnlike many synthetic materials, Imidan has a carefullyshort residual effect and a relatively low acute destroyed bytoxicity. If Prokopy does not spray, 80−90% of his boiling, burning,fruit suffer at least some PC damage. Imidan is or soaking in oil.not allowable in organic production. See The drops on the —The plum curculio: Adult female onAppendix 4 for more detailed information on two or three plum, showing the circular feedingProkopy’s low-spray program. outside rows of punctures and the crescentric egg- the orchard are laying punctures. Enlarged. (USDA)A 5% formulation of rotenone provides some likely to be morecontrol; however, coverage must be very heavily infestedthorough, and applications made at roughly than those further in the orchard. Sometimes theweekly intervals for a total of 12−15 treatments to fruit that drops in May or June contains very fewkeep crop damage under 25% (9). While such a PC larvae. In such cases the early dropping mayprogram is technically “organic,” frequent // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 5
  6. 6. Orchard establishment “Because of plum curculio’s preference for maple woodlots as overwintering sites and its low winter survival in other locations, it seems advisable to establish orchards as far removed as possible from maple woodlots. Furthermore, because plum curculio also attacks crabapple, wild apples, pears, plums, cherries, peach, apricot, quince, and hawthorn, apple orchards should be kept away from these trees, and wild host trees should be removed from the surrounding area. “A stone mulch about 1 foot in radius around the tree trunk with a thick spoiled hay mulch out of the dripline is likely to encourage many predators of plum curculio. Efficient mice guards must be used in conjunction with mulches. “A diverse array of ground vegetation with small flowers is likely to attract parasitic wasps, which may parasitize not only plum curculio but also many other pests. This would need to be mown during apple blossom to avoid attracting the bees away from the apple pollination. Bare soil in the orchard is probably also unattractive to plum curculio, but its dependence on heavy herbicide use and associated soil erosion makes it an unsuitable solution. “Sites adjacent to maple woodlots could be made less attractive by planting one or two rows of conifers along the edge to discourage plum curculios from entering the woodlot in the fall. Coniferous leaf litter scattered along the woodlot edge might also repel the plum curculio.” Dr. Stuart B. Hill (6)be attributable to heavy fruit set, poor pollination, inch of soil. The most desirable time to beginor both (9). cultivation for destruction of pupae appears toThe adults may be knocked from trees by jarring be about three weeks after the infested fruit startsthe limbs with a padded board. They “play to drop from the trees. Cultivation should bepossum” when thus disturbed, and will drop continued at weekly intervals for a period offrom the tree to a tarp or sheet placed below. several weeks. Cultivation before the curculiosAdult curculio beetles caught in this manner can pupate is of little value. If the cocoon is brokenbe crushed or dropped into a can of kerosene. before pupation occurs, another cocoon is madeTree jarring should be done early in the morning, by the larva.while it is still cool, or the beetles will fly away.For significant control to be achieved by this Covering the drops with soil before the larvaemethod, trees must be jarred and beetles emerge from them is undesirable since it protectsdestroyed every morning for 4−6 weeks, the larvae from drying. Research done in the 50’sbeginning at pink. Growers who have used this in Arkansas indicated that cultivation canor similar methods have reported no better than provide significant PC control (12); however,around 50% control (10, 11). Because of the labor long-term reliance on this method could result inintensity and less-than- commercial levels of erosion and depletion of soil organic matter.control, tree jarring is most commonly used tomonitor for the presence of adult beetles rather Free-ranging fowl such as chickens, ducks, andthan for control. geese can be encouraged to scratch for the larvae and adult weevils by mixing poultry feed into theDisking during the pupal period (“cocoon stage”) soil under the trees. Or the fowl could be movedis a method of mechanical control. The pupa of along the edge of the orchard in mobile chickenthe plum curculio is very fragile. If its cocoon is coops. Dr. Stuart Hill, an entomologist formerlydisturbed, the pupa fails to transform into an at McGill University, has written that everyadult. Pupation usually occurs within the upper // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 6
  7. 7. Seasonal history of plum curculio (USDA)successful organic orchard he’s visited “had Among the most promising non-toxic controls forseveral hundred chickens in them as pest codling moth is mating disruption usingcontrol agents” (6).Codling moth pheromoneschemicals naturally produced by insects as a means of communication. During the The codling moth, mating period, female codling moths release Cydia pomonella, is pheromones that signal their location to males. present throughout By releasing quantities of these pheromones into North American the orchard, the grower can confuse and disrupt apple growing the moth’s mating cycle. regions. Prior to the advent of This approach faces two general Codling Moth synthetic pesticides, problemsdifficulties with sustaining an even, the codling moth long-lasting distribution of pheromoneslarva was the proverbial “worm in the apple.” throughout the orchard, and complications dueRelatively cold regions may have only one to the biology and initial distribution of thegeneration of the codling moth, while in the codling moth. For instance, dispensers canwarmest apple growing areas the codling moth release pheromones too slowly or too quickly,may pass through 2 to 3 generations per season. thus allowing mating to occur. Orchard layout isGrowers who spray Imidan for the plum another consideration. For best results, treescurculio will find that these sprays also take care should be evenly spaced and of equal heights,of most of the codling moths.Several organically since treeless spaces and taller trees interrupt theacceptable controls are available and discussed pheromone spread. Cold weather can cause toobelow. Also see the section on kaolin clay. little pheromone release and hot weather can cause too fast a depletion. Since the pheromones actually attract male moths, fruit damage can be // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 7
  8. 8. worse if pheromone levels drop low enough to the eggs hatch, the larvae will quickly enter aallow mating to occur (13). fruit and again be protected from sprays.Dispensers should be placed as high in the treesas possible, since mating can occur in the air A new product formulated to attract and kill theabove the dispensers. For pheromone dispensers codling moth, Last Call, is a combination of ato be effective, it is important to use them at the pheromone and the insecticide permethrin. Itsrecommended rate per acre (14). One success is not as sensitive to the variables in land,improvement currently being tested is an aerosol wind, and canopy that make mating disruptiondispenser, nicknamed the “puffer,” which uses a tricky. The use of the insecticide is appropriate fortimer to periodically spray pheromone into the low-spray programs, as the pheromone makes theorchard air. These puffers could overcome some insecticide more selective (better-targeted at theof the problems mentioned above and reduce the pest.) Last Call has a 28−42 day field life, islabor requirement of tying the pheromone twist- insoluble in water, and does not harm beneficialsties onto orchard trees (15). (18). For more information on Last Call contact IPM Technologies (see Appendix 1).When codling moth populations are high,pheromones may need to be used in Bacillus thuringiensis (Bt), a naturally occurringcombination with an insecticide spray (16). For bacterium, can be used in organic production oforganic growers it will probably not be feasible apples against the codling moth, but with limitedto achieve adequate suppression using mating results. Other lepidopterous (worm) pests, suchdisruption alone. Growers in California have as leafrollers, are much more susceptible to thesignificantly improved codling moth control by bacteria (19). Products formulated from thiscombining mating disruption with black light microorganism include Dipel, Javelin, andtraps. Both male and female codling moths are Thuricide. New formulations with longer fieldstrongly attracted to black light (17). These life may be more effective against the codlingtraps are available from Superior Ag Products moth; however, since some of these are the result(see Appendix 1). of genetic engineering, organic growers may need to contact their certifying organizations toPrior to the development of the mating check on acceptability.disruption system, pheromones were usedprimarily for monitoring to determine the best The trichogramma wasp is increasingly used intiming for spray applications. Appendix 3 details U.S. orchards as a biological control organismthe monitoring tools available for detecting this against codling moth. The wasps can bepest by using “degree days”. Since insects are ordered from insectaries, which ship them ascold blooded, their physical development pupae inside parasitized grain moth eggs gluedprogresses according to the temperatures to to perforated cards (100,000 trichogramma perwhich they are exposed. Once the developmental card). Each card can be broken into 30 squares,rate of a species at certain temperatures has been allowing for even distribution in orchards anddetermined, weather monitoring can forecast fields. Trichogramma parasitize freshlywhen an event, such as egg hatch, will occur. deposited moth eggs, so release of the adultThis information can be used to implement wasps should be timed to coincide with mothcontrol methods, such as pesticide applications or egg-laying (see Appendix 3). The adultcultural manipulations, so that they are used at trichogramma feed on insect eggs, nectar,the most effective time in the pests life cycle. pollen, and honeydew. They live much longerThere are several “windows” in the pests and destroy more codling moths whendevelopment that, if detected, can greatly supplied with nectar. Good nectar and pollenincrease the effectiveness of control measures. sources in and around the orchard, such asDetermination of these critical periods is borders or strips of unsprayed alfalfa, sorghum,especially important, since codling moth eggs are sunflower, corn, clovers, and wildflowers, willfairly resistant to chemical treatments, and once increase trichogramma parasitism of pest eggs. Beneficial organisms are not sufficient by // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 8
  9. 9. ATTRACTING AND CONSERVING BENEFICIAL INSECTS “Farmscaping” is the use of hedgerows, insectary plants, cover crops, and water reservoirs to attract and support populations of “beneficial” organismsnatural predators of crop pests. Because of the inherent ecological stability of a permanent planting of trees, apple orchards are generally more amenable to farmscaping than annual cropping systems. Farmscaping concepts can be used to design an agro-ecosystem that increases plant diversity, confuses pest insects, and disrupts pest life cycles. The goal is to create a more species-diverse environment by providing a variety of habitats (niches) for organisms to exploit. Farmscaping practices will not eliminate pest problems, but they can help reduce pest pressure and, when integrated with cultural control methods, contribute to minimizing the use of chemicals. However, simply using a random selection of flowering plants for farmscaping may favor pest populations over beneficial organisms, so it is important to include only those plants (and planting situations) that best support populations of beneficial organisms. Ron Prokopy (8, 22) has written about the management dilemma faced by some farmers in trying to implement farmscaping concepts: how to manage a resource that has both positive and negative impacts on crop yield and/or health. To illustrate, Prokopy notes that the presence of brambles in an apple orchard supports significant populations of phytoseiid predatory mites. However, brambles are important hosts of two major summer diseases of pome fruitsooty blotch and flyspeck. Should the farmer retain the brambles and ensure the positive effect of the mites, or reduce disease pressure by eliminating them? This is a good example of the quandaries presented by ecological pest management. Flowering plants provide various forms of food to beneficials, including nectar, pollen, honeydew (from aphids on plants), and herbivorous insects and mites. A mix of plants such as dill, hairy vetch, spearmint, Queen Anne’s lace, buckwheat, yarrow, white clover, tansy, cowpea, and cosmos will attract and conserve many beneficials, including trichogramma wasps. It may not be necessary to sow flowers or put much time into planning to take advantage of beneficial-sustaining habitat. When low-spray orchardist Guy Ames mows the paths between his apple rows, he simply leaves an un-mown strip down the middle of each path, where weeds such as Queen Anne’s lace, clovers, and vetches can go to flower. He has noticed a marked increase in beneficials in the orchard, and enjoys the aesthetic effect of wildflowers blooming among the apple trees. For further information, including resources and seed suppliers, see the ATTRA publication Farmscaping to Enhance Biological Control.themselves to effect a commercially acceptable Sanitation and cultural practices can help tolevel of control; rather they play a potentially reduce codling moth populations. Woodpiles,potent part in an overall, long-range ecologicalmanagement strategy. Best results are usually boxes, and bins can be a major source ofobserved after three to five years of releases, as reinfestation, so these should be kept away fromthe population of beneficials grows. As the orchard. If wooden crates or boxes aretrichogramma are very sensitive to pesticides, discovered to contain codling moth pupal cases,the spraying program should be designed to they can be disinfested by scorching with aminimize chemical interference with the propane torch.biological control cycle (20). Codling moth larvae can also be intercepted as they descend the trunk to pupate in bark crevices, // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 9
  10. 10. soil, and certain weed stems. Wrap the trunks Like the plum curculio and the codling moth, thewith corrugated cardboard, which will provide apple maggot has been suppressed in trials by the kaolin clay application discussed attractive, artificial pupation site. In areaswith only one generation of codling moth, Oriental fruit mothremove and burn the cardboard at the end of theseason. If there are two or more generations, the Usually thought of as a pest of stone fruits, thiscardboard should be removed and destroyed insect has adapted toabout a month after the first larvae moved down exploit apples, primarilyto pupate. To determine the timing of this larval in the South and uppermovement use the degree day method described South. It is a direct pestin Appendix 3, or employ a trap of a six-inch- of the fruit, tunnelingwide burlap strip painted with Tanglefoot, randomly throughoutwrapped around the trunk just above the the flesh (in contrast tocardboard wraps (21). the codling moth, which primarily feeds aroundApple Maggot the seed cavity). It is relatively easy to controlAnother major with insecticides, Oriental Fruit Mothapple pest is the especially if sprays areapple maggot, timed by using commercially available pheromoneRhagoletis traps. Unfortunately, due to differing life cycles,pomonella. It is a the sprays for plum curculio and codling moth doproblem primarily not control the Oriental fruit moth. Sprays for thisin the Northeast pest are usually needed later in the season, whenand the upper they may be disruptive to beneficial insects. AMidwest. To Apple Maggot pheromone-based mating disruption systemmonitor adult (Isomate-M) has proved effective and ispopulation levels, red spheres covered with a registered for use on apples.sticky coating and impregnated with a fly-attracting odor are hung in the orchard. If Minor and induced pestsenough spheres are used, the flies can also bemass-trapped. This technique may reduce or All of the aforementioned insects are directeliminate the need for pesticide applications. pests of the apple fruit. Most of the so-calledThe spheres are available from several suppliers, minor pests mites, aphids, scale, leafrollers,including Gempler’s, Inc. (see Appendix 1). and othersfeed primarily on the stems and foliage. In general, these pests can be toleratedRemoving hawthorns and abandoned or in much higher numbers than the direct fruitneglected apple trees near the orchard should pests, but they can occur in high enoughhelp in reducing fly influx into the orchard. The numbers to seriously weaken the tree, resultingflies are susceptible to pyrethrum, rotenone, and in reduced quality and quantity of fruit anddiatomaceous earth. Also, University of perhaps tree death.Massachusetts research indicates that a Bordeauxspray residue on the apples deters egg-laying bythe flies (however, it should be noted that Many of these minor pests are “induced”Bordeaux sprays at this timeroughly 30 days peststhat is, they have achieved pest statusfrom petal fallcould induce leaf burn and because pesticides that were targeted for majorrusseting of the fruit). pests killed beneficial organisms that would otherwise have kept these minor pests below damage thresholds. // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 10
  11. 11. Non-selective pesticidesthose that affect through early May, and begin laying eggsbeneficial and pest organisms alikewhether beneath bark scales on the tree. The graft unionorganic or synthetic, can cause this phenomenon. is a favorite place for egg deposition. Upon hatching, the larvae burrow under the barkDr. Ron Prokopys low-spray system (see and feed on the cambiumthe layer of tissue justAppendix 4) is largely based on thesupposition that avoidance of non-selective pesticide use during mid andlate season will preserve adequatenumbers of beneficial organisms,which will control these minor pests.Interestingly, organic growers whohave to rely on frequent sprays of non-selective botanical pesticides(especially rotenone and pyrethrum)may suffer more from induced pestproblems than low-spray growerswho are able to stop spraying earlierin the season.There are relatively non-toxic ways tocontrol most of these minor pests,should they become troublesome. Flathead apple tree borer Chrysobothrs femorata: a. larva; b.Bacillus thuringiensis is effective against adult beetle; c. pupa. About twice the normal size. (USDA)lepidopteran pests such as leafrollers. underneath the bark. Development is usuallyOil sprays (dormant and summer types) are completed in one year, but sometimes two yearseffective against mites, scale, and eggs of some are required.other pests. Oils should not be used inconjunction with or within 30 days of sulfur Maintaining trees in good vigor is important first-applications, since a combination of the two can line protection from flatheaded borers, since acause phytotoxicity (damage to the plants, in this tree in good vigor will be able to drown ancase leaf “burning”). M-Pede insecticidal soap invading larva with sap. Drought-stressed treesis effective against aphids and mites if coverage is are much more susceptible to borers; therefore,adequate. Beneficial mites, ladybeetles, green adequate water is essential.lacewings, and parasitoid wasps are alsocommercially available and can be helpful The roundheaded apple tree borer, Saperda candida,against many of the minor pests. The kaolin clay attacks the tree near ground level, and is thereforespray discussed below has been found to control harder to exclude using a wrap or paint. As withleafhoppers and leafrollers, and to provide the flatheaded borer, keeping the tree in good vigorsignificant levels of suppression against mites, is the first line of defense. Removing serviceberryapple suckers, stink bugs and thrips. trees (Amelanchier spp.) in close proximity to the orchard may also help, as the serviceberry is aBorers preferred host for the roundheaded borer.Another important production concern for Another borer exclusive to the East, the dogwoodorganic or low-spray apple growers is borer borer or Synanthedon scitula, feeds primarily oncontrol. There are two species of flatheaded burr knot tissue on clonal rootstocks. Burr knotsborers that may invade apple trees. Chrysobothris are clusters of root initials which develop on thefemorata is the species endemic to the East. On above-ground portion of some rootstocks.the Pacific coast, C. mali fills a similar niche. Planting so that the graft or bud union is withinAdults emerge from woodland trees in late April // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 11
  12. 12. one inch of the soil should inhibit the safe—and thus exempt from requirements of adevelopment of burr knots, thereby preventing tolerance for residues.dogwood borer attack. Painting exposed burrknots with interior white latex paint is alsohelpful. Unless the infestation is heavy, The spray was developed by Drs. Michael Glenndogwood borer damage is generally not as and Gary Puterka (24) of the USDA/ARS atimportant as that caused by flatheaded or Kearneysville, WV, in cooperation with theroundheaded apple tree borers. Engelhard Corporation (see Appendix 1), which began marketing the product in 1999 on aFor all species of borers, the larvae can be limited basis. Surround will be available in 2000removed from the trunk with a jackknife or piece in much of the U.S., and it was listed by Theof wire. Look for signs of borer damage, such as Organic Materials Review Institute for use infrass mixed with sawdust, at the base of the tree organic production on March 7, 2000.and at the pests entry hole. Because theroundheaded borer may burrow deep into roots, Surround is sprayed on as a liquid, whichit is important to check routinely (at least twice evaporates, leaving a protective powdery film on theduring the growing season; e.g., once in May and surfaces of leaves, stems, and fruit. Conventionalagain in September) for borers, or they can extend spray equipment can be used, and full coverage isbeyond the range of manual removal. important. The film works to deter insects in several ways. Tiny particles of the clay attach to the insectsPerhaps the best non-chemical protection from all when they contact the tree, agitating and repellingspecies of borers is to wrap the bottom 12−18 them. Even if particles don’t attach to their bodies,inches of the trunk in window screen (metal, the insects find the coated plant or fruit unsuitablefiberglass, or nylon are all effective). Secure the for feeding and egg-laying. In addition, the highlytop with a twist-tie, being certain to loosen and reflective white coating makes the treere-tie at least once a year. The bottom should be unrecognizable as a host (25).snug against the ground or also secured with atwist-tie. Painting trunks with interior white The standard Surround spray program for plumlatex also helps reduce borer attack. curculio and first-generation codling moth starts at first petal fall and continues for 6 to 8 weekly sprays or until the infestation is over.KAOLIN CLAY Discontinuing sprays at this point will leave little or no residue at harvest because of rain and windA new particle film spray, marketed under the attrition. If a full-season program is used totrademark Surround WP Crop Protectant, may suppress later-season threats such as appleprove to be the key to making organic apple maggot, growers will need to use aproduction economically viable in the Eastern scrubber/washer to remove any dust remainingU.S. In addition to suppressing plum curculio, on the fruit for fresh market sales. Although thisSurround™ provides adequate control for most, if residue is not considered harmful, it might benot all other insect pests of apples, with the possible considered unsightly by consumers. However, theexception of the wooly apple aphid. dust residue is not a problem for processing fruit.The active ingredient in the product is kaolin Trial applications of the spray showed thatclay, an edible mineral long used as an anti- where plum curculio damage was 20–30% incaking agent in processed foods, and in such unsprayed checks, the treatments receiving theproducts as toothpaste and Kaopectate. There particle film had only .5–1% damage. Dr.appears to be no mammalian toxicity or any Puterka is careful to say that his trials indicatedanger to the environment posed by the use of “suppression” of PC damage rather thankaolin in pest control. Surround has already complete control, but for the organic growerreceived EPA registration, and EPA considers the looking to achieve an economic level of control,active ingredient GRAS—generally recognized as the distinction is probably not relevant. What // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 12
  13. 13. the researcher terms “suppression” in these orchard have shown over 90% control of theUSDA trials is very close to control, far closer “big ones” codling moth, plum curculio, andthan any other organically suitable option. apple maggot. While Surround has also had a positive effect on fungal diseases like sooty blotch, fly speck, and fireDr. Puterka has speculated that in areas where blight, Rice cautions that it is not a panacea. It hasPC pressure is especially heavy (for instance in had no effect on apple scab, a disease that oftenunsprayed trees in northwest Arkansas which poses a bigger problem to growers than insectcan suffer up to 90% damage), shortening the pests (initial research with kaolin focused on itsrecommended spray interval from 7–10 days to potential for disease suppression, but the resultsevery 5 days might provide the levels of were inconsistent.)suppression obtained in the trials (26). Although reluctant to make “overlyAlthough at first glance the film may appear to aggressive claims” about the product, Riceblock light, Surround actually increases net says that Surround is far more useful thanphotosynthesis, and can provide secondary any other organic options available on thebenefits to the trees’ overall health according to market. The only disadvantage he cites is theDr. Glenn. Surround keeps the tree cool so that necessity of washing the clay off the fruit afterphotosynthesis can continue longer into the harvest. Referring to the uniformly whiteafternoon on hot days, after untreated trees have appearance of the trees after spraying, Ricealready shut down because of heat stress. In a says, “It looks like Christmas. People whotwo-year study, ‘Empire’, when sprayed during drive by sometimes stop to inquire ifthe first six to eight weeks after petal fall, had something is wrong.”increased yields and increased red color.Growers have reported similar results with Rice has been farming for the last twelve years, and‘Stayman’ and ‘Gala’. An MSU study reported raises several small fruits, including two dozenincreased return bloom where Surround had varieties of apples, on seventy acres in westernbeen used the previous season. Growers in hot Maryland. The apples are marketed throughareas benefit from a marked groceries in thereduction in sunburn Washington,damage, often 50% or D.C./Maryland area, agreater. CSA, and a farmers’ market in Dupont Circle. Plans are underway toFARMER PROFILE: start a mail order businessEric Rice, Middletown, via the Internet.Maryland “Some people are picky,” he says, “but directOne of the first orchardists marketing gives us ato use the kaolin spray, Eric chance to talk to themRice is confident the product will help him fare about blemishes on the fruit.” Rice also contractsbetter in his packout next year. Rice, whose farm with a commercial kitchen in Lancaster, inis certified organic, hopes to boost the neighboring Pennsylvania, to make apple saucepercentage of select grade fruit from 50% to 70% and cider. He observes regretfully that there is notof his apple crop. He expresses optimism about a single processing kitchen in the entire state ofSurround’s effectiveness against insects like the Maryland. “We’ve lost our farm infrastructureplum curculio, codling moth, leaf rollers, mites because of suburban sprawl.”and aphids. “It doesn’t bother beneficials,” hesays, adding that the ladybugs and other Value-added products, according to Rice, requirepredators continued to thrive in the rich ground huge packaging and processing costs and are notcover of clover and grass. Trials at the Rice an easy way to make money. “Moreover,” he // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 13
  14. 14. says, “I don’t believe organics should be food only Understanding genetic disease resistancefor rich people. Our applesauce, for instance, sells By plant breeders design or by chance, adoesn’t return a whole lot of money. Our apples plant may exhibit natural, heritable resistance toin the ballpark of the conventional product and a disease. Because disease-resistant cultivarstypically retail for under $2/lb. Our ‘Gala,’ a have become increasingly important asdifficult variety to grow, sells for $1.29− growers try to reduce pesticide use, it is1.59/lb.” The margins are gained not from important to understand some principles ofhefty premiums, he says, but by eliminating genetic disease resistance.middlemen and absorbing their costs (as wellas their work.) Resistance to a disease can be partial or complete (immune). Resistance exists on aFollowing a two-year trial of Surround, Rice continuum and may be expressed in termsnow reports virtually no problems with such as “very suscepticle,” “moderatelyinsect pests, including the coddling moth, susceptible,” “susceptible,” “moderatelythe apple maggot, and the plum curculio. resistant,” “resistant,” “very resistant,” etc.Apple scab is treated with copper sprays In some cases, numerical values have beenpre-bloom, insecticidal soap, and summer assigned by researchers to represent a givenoilthe last option, he notes, is not as level of resistance such as ”60% resistant.” Ifeffective. In addition, the leaves are cleared resistance is strong enough, the grower willevery fall, rotting or withered fruit is not have to spray to control the disease.removed from the ground, and winterprunings are burned. “There’s no single It is important that the grower understandanswer,” says Rice, “but part of the solution that given strong enough disease pressure lies in the use of disease-resistant cultivars, high levels of inoculum and the properwhich we grow. ‘Gala’ is tremendously environmental conditions  medium levelsscabby while a number of antique varieties of resistance can be overcome and the plantare fairly resistant. Still, every year we lose can suffer some infection.more to scab than to insect pests.” Another principle to understand is thatRice relies on a variety of products to boost resistance to one disease never impliesfertilitygreen sand, rock phosphate, compost resistance to any other disease. A givenfrom beef manure and leaf litter, fish meal, and variety may exhibit strong resistance to onepelletized poultry litter. For a cover crop, he disease, yet be highly susceptible to another.uses clover and Companion grass, a cross A good example of this is the cultivar ‘Prima,’between dwarf fescue and rye. Experience has which is apparently immune to scab but soled him to conclude that there is a correlation susceptible to cedar rust that it will defoliate ifbetween high nitrogen availability and high disease pressure is high. Growers who intenddisease pressure. Following the deliberate to forego all sprays for diseases need to beunder-use of nitrogen, he has also noticed an certain to get trees resistant to the diseasesincrease in yields. present in their area.For information, contact Eric Rice at 6201 Harley Lastly, the term tolerance is often usedRoad, Middletown, MD 21769. interchangeably with resistance.Phone: 301-371-4814. Technically, tolerance refers to the ability of a plant to undergo infection but without appreciable losses in growth or yield. A treeDISEASES in good health will be tolerant to many diseases. For instance, a vigorous tree thatTo identify diseases present at a specific orchard site, suffered a cedar rust infection early in thecontact your Cooperative Extension Service. season may show few signs of that infection later in the same season. The disease // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 14
  15. 15. Table 2: Approximate number of hours of continued wet foliage required for primary apple scab infection at different air temperature ranges (27). 32°−40°F 48 hours 40°−42°F 30 hours 42°−45°F 20 hours 45°−50°F 14 hours 50°−53°F 12 hours 53°−58°F 10 hours 58°−76°F 9 hours 76°− 11 hoursresistance/susceptibility of many apple suppliers listed in Appendix 1). The equipmentvarieties is charted in Appendix 2. necessary to monitor and detect infection periods includes a leaf wetness meter, a rain gauge, and aApple scab temperature recorder. These instruments areplaced in the orchard, or at the growersApple scab, caused by the fungus Venturia home if the site is representative of orchardinaequalis, is the most serious apple disease conditions (27).worldwide. The pathogen overwinters in deadleaves on the ground. Spores are released during The use of scab-resistant varieties is the best long-spring rains, landing on and infecting leaves and term strategy for organic growers to pursue, sincefruit. Rain, length of leaf wetness, and temperature such trees eliminate the necessity for applyingdetermine apple scab infection periods, and the fungicides. See Appendix 2 for names of scab-degree of infection depends on the combination of resistant varieties.these factors. Spores can germinate and causeinfection only when they are kept wet over a Apple scab can be controlled on susceptiblecertain minimum period of time at temperatures varieties by timely sprays with fungicides. Forranging roughly from 32° to 79° F. If they are not the organic apple grower there are threecontrolled, they will give rise to “secondary” commonly used materials: sulfur, lime-sulfur,infections later in the season. Primary and second- and Bordeaux mixture. Bordeaux mixture isary infections may occur simultaneously early in copper sulfate plus lime. All of these sulfur-the season, depending on weather conditions (27). containing fungicides can cause damage to the If the grower is relying on protective-type foliage or blossoms if used incorrectly, so heedingfungicides, such as all organically acceptable label cautions is important. All these fungicidesfungicides, trees should be treated whenever there are effective against scab spores but have to beis a chance of primary infection (28). applied before spores have a chance to germinate. To be effective, the trees must be diligentlySecondary infections begin when summer spores sprayed or dusted before, during, or immediately(conidia) develop in lesions on leaf and bud after a rain from the time of bud break until alltissues, to be released during wet periods and the spores are discharged. If these primarydisseminated throughout the tree. Secondary infections are prevented, there will be less needinfections blemish and deform the apples, and to spray for scab the remainder of the season (29).will also weaken the tree. The number of If primary infections do develop, spraying willprimary and secondary infections in a year have to be continued throughout the season.depends on the amount of rain. The warmer theweather, the more quickly conidia development In most areas, applications of fungicidesin thisfollows primary infection (ranging from 18 days case, sulfur productsare based on theat 31°−40°, to 7 days at 71°−75°). phenological development of the trees. Spraying begins in the spring when a wetting period (rain)Fortunately, good scab infection prediction andmanagement programs are available (check with // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 15
  16. 16. is sufficiently long at the existing temperature to blotch, black rot, bitter rot, and white rot (moreproduce an infection. Spraying is then repeated on these below).every 5 to 7 days, or according to rainfall, untilpetal fall. It is important with protective-type Because the scab fungus overwinters on thefungicides, such as sulfur, to insure that new fallen apple leaves, small-scale growers cantissues on rapidly expanding young leaves and largely eliminate the primary scab inoculumfruit are always covered with fungicide during an and control the disease by raking andinfection period. destroying (burying, burning, composting) the fallen leaves.Several types of synthetic fungicidesincludingthe sterol inhibitors and the strobilurinsseem to Other approaches to reducing or eliminating thecombine a high level of safety with the qualities primary inoculum might include anything thatapple growers need for reducing the number of would hasten the breakdown of the fallen leaves.fungicide sprays. One of the sterol inhibitors Fall applications of urea have resulted in goodlabeled for apples, myclobutanil, has a broad primary scab control (32), indicating perhaps thattarget range, meaning it works on all the major other fertilizer materials could do likewise. Thereearly season apple fungal diseasesscab, rust, is evidence that earthworms aid in scab controlmildew. It also has excellent kickback action, by speeding the breakdown and incorporation ofallowing growers to wait for infection periods the fallen leaves.before spraying, no phytotoxicity problems, anderadicative potential for primary scab inoculum Fall fungicide applications also have shown(30). In terms of safety, myclobutanil scored promise for primary scab control. One of thenegative on the Ames tests for mutagenicity and major problems with using sulfur compounds iscarcinogenicity and has a very low acute toxicity phytotoxicity, but this concern could be largely(LD-50, 1600 mg/kg body weight of rat) (31). circumvented by spraying in late autumn (afterUnfortunately, myclobutanil appears to provide harvest but before leaf fall) when it is not very important if the leaves are damaged. SUPPRESSING DISEASES WITH COMPOST Research with other fungicides has proven the basic efficacy of thisOrganic farmers and gardeners have long touted the disease- approach.suppressive benefits of compost. Recent research has confirmedthis natural suppression, made some headway in understanding Other unconventional approaches toit, and developed methods for producing consistently scab control that show some promisesuppressive composts, a major step toward greater use by include a variety of plant extracts (33)growers. and even compost tea (34). Refer toPlant pathologists distinguish two types of disease suppression ATTRA’s Compost Teas for Plant Diseasein compost (and in soil). General suppression is attributable to Control for more information.many different microorganisms that either compete withpathogens for nutrients or produce general antibiotics that Fire blightreduce pathogen survival. Specific suppression is attributed toone or a few organisms that parasitize the pathogen or induce Fire blight is caused by the bacteriasystemic resistance in the plant to specific pathogens (this works Erwinia amylovora, which can bein much the same way as a vaccination). transmitted by bees,If composts can be produced on a large scale with reliable and aphids, and other insects, as well as byquantifiable disease suppressive qualities, growers will be more wind and rain. Warm, wet conditionslikely to use them in place of fungicides. The nursery industry is foster the bacteria’s reproduction andalready using disease-suppressive compost widely and spread within and among trees, and largeroutinely, and its widespread use in crops such as apples is numbers of new infections can occurlikely in the near future (35). within minutes after rain or heavy dew hits. Fire blight will be a problem only inlittle control of the summer diseasessooty years when the weather is conducive to its // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 16
  17. 17. spread. Affected branches wither and turn black SUMMER CUTS QUESTIONEDor brownish black, as if scorched. Most branchtips, once “Whether to cut and how to cut out active blightinfected, wilt rapidly, taking on the characteristic infections during the growing season is a subject ofshape of a “shepherd’s crook”. Having gained continuing debate. We recommend a very aggressiveentry to the tree through blossoms or lush new cutting of all branches that show symptoms onlygrowth, the bacteria spread internally through the when the incidence and distribution of infections isstems, and begin to work towards the roots. In light and the job can be completed quickly.resistant varieties, the bacteria rarely invade “When blight is moderate to heavy, the success ofbeyond young wood. (See Appendix 2 for even the most well-intentioned cutting effort isinformation on resistant varieties.) Under the questionable. In such cases, the focus…should bebark, the bacteria form a canker where they will on removing infections high in the tree, those thatoverwinter, surviving to infect more trees the threaten the central tree stem, and removing severelynext year. damaged trees quickly.Once infection has occurred, there is no spray or “While the bacteria are often present in healthy tissuesother treatment, beyond quickly cutting out far ahead of visible symptoms, high levels of reserveinfected limbs, that will minimize damage. carbohydrates in living bark tissues deny theSprays of agricultural grade streptomycin have pathogen water and limit symptom development.been the standard commercial control since the Cutting through such colonized but symptomless branches breaches this natural defense and induces1950’s, applied at early bloom to prevent infection. the formation of cankers around wounds, even whereOrganic certifying groups are mixed on their both bark surface and pruning shears have first beenacceptance of streptomycin, an antibiotic sterilized with bleach or alcohol.produced by cultured fungi, for fire blightcontrol. Bordeaux mix and other copper “To avoid new cankers around cut sites, make cutsformulations sprayed at green tip stage are during the growing season only into two-year-old ororganic options that provide some protection older wood and at least 4 to 5 inches short of the nextfrom infection. For best results, these should be healthy branch union, leaving an “ugly,” naked stub.applied to all the trees in a block, not only the Cankers that form around the cut can be removedblight-susceptible varieties (36). during the regular dormant pruning effort when the temperature is too cold to allow the bacteria to formIn 1996 a new biocontrol product called another canker. Failure to follow this “ugly stub”BlightBan™ came on the market. BlightBan is a procedure can actually increase the number and distribution of inoculum sources in the orchard thatformulation of the bacteria Pseudomonas will fuel yet another epidemic the next season.”fluorescens, strain A506. P. fluorescens is a non-pathogenic competitor with E. amylovora, and as Paul W. Steiner (36)such does not directly kill propagules of E.amylovora; rather, it occupies the same sites that E. Western apple-growing areas, E. amylovora hasamylovora would, provided it gets there first. developed resistance to streptomycin.) By itself,Therefore, in order to be effective, BlightBan BlightBan may provide 50% suppression. Itshould be applied to newly opening flowers(multiple applications will probably be necessary) cannot be used in combination with copperor applied in combination with streptomycin (P. sprays. The biocontrol bacteria live only aboutfluorescens, strain A506 is resistant to three weeks in the orchard, and there is no carry-streptomycin). In fact, research indicates that fire over from year to year (37, 38). BlightBan isblight suppression is best when streptomycin and marketed by Plant Health Technologies (seeBlightBan are combined. Appendix 1).Using the two together can reduce the amount of A computer software program called Maryblytstreptomycin sprayed each year, which may help is available to help guide the grower in timingto protect the antibiotic’s effectiveness. (In some // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 17
  18. 18. A promising biocontrol technique employing Fire blight development is greatly favored by thehoneybees as couriers of beneficial bacteria is under presence of young, succulent tissues. Where firedevelopment by USDA scientists. The researchers blight is a problem, cultural practices that favorplace the beneficial bacteria in a shallow tray at thehive entrance. The bees walk through the tray, pick moderate growth, such as low fertilization andup the beneficial bacteria, and deliver it to the limited pruning, are during pollen and nectar collection (39) Powdery mildew Powdery mildew is primarily a foliar disease, but it can affect fruit if the infection is severe. Some apple varieties, such as ‘Braeburn,’ are so susceptible that infection curls, distorts, and discolors leaves. In such cases, photosynthetic capacity is reduced and tree vigor and health suffer.antibiotic sprays. The grower enters dailyminimum and maximum temperatures, rainfall, Areas where spring and summer humidity areand stage of blossom development, and the high are most likely to foster powdery mildewprogram predicts infection events and symptom problems. There are resistant varieties (seedevelopment for most phases of fire blight. The Appendix 2), and mildew can be controlled with many fungicides including the aforementionedMaryblyt program may be purchased from sulfur compounds.Gempler’s, Inc., and further information on theprogram is available at the Kearneysville web site(see Appendix 1). Cedar apple rustA rule of thumb is to spray just before rain or The fungus that causes this disease moves back-heavy dew is expected during bloom, when and-forth between Eastern red cedars (actuallyaverage temperature is 60°F or higher, and to junipersnot true cedars) and apples, and sorepeat in four days if these conditions persist. can be a major problem where Eastern red“Routine” sprays, in the absence of wet, warm cedars are endemic. In order to complete its lifeconditions, are often unnecessary. Overuse of cycle this fungus must spend part of its life onstreptomycin should be avoided because of the Eastern red cedar; therefore, it is theoreticallydanger of inducing resistance in the pathogen possible to eliminate the disease by eliminatingpopulation. Again, streptomycin is not the cedars within a given area. However, theeffective against the “shoot blight” phase and spores can be windborne up to 2−3 miles (40), soshould never be used when symptoms  eradication of the disease in this manner is often“burned” branch tips  are present (36). impossible or impractical.Proper sanitation is the most important measure Nonetheless, if cedars are not too numerous onfor controlling fire blight once it has infected a a given site, their removal around thetree. During the winter all blighted twigs, immediate orchard vicinity can certainlybranches, and cankers should be cut out about 10 reduce the inoculum reaching the applecm below the last point of visible infection, and foliage. There are many rust-resistant appleburned. After each cut, the shears should be varieties. Only a few varieties, most notablydipped in alcohol or a strong bleach or Lysol ‘Golden Delicious’ and its progeny, are susceptible to the point of defoliation (seesolution1 part household bleach or Lysol to 4 Appendix 2).parts waterto avoid transmitting the diseasefrom one branch to another. Lysol is less corrosive Many fungicides are effective against rust,than bleach to the metal parts of the pruners. including the sulfur compounds. If the grower is observant, he or she may be able to time the sprays to coincide with the springtime appearance of // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 18
  19. 19. orange gelatinous “horns” on the galls on the Little attention has been given in university trialscedar. This bizarre-looking structure is actually to screening for resistance to the summer rots.the fruiting stage of the fungus. The “horns” One reason for this lack of research has been therelease the spores that infect the apple trees. general perception that there simply wasn’t resistance, “just degrees of susceptibility.”The summer rots However, on closer examination, Dr. Curt RomWhere summers are warm and humid (including (41) of the University of Arkansas has notedmost of the Eastern U.S.), the summer rotsblack distinct differences among cultivars in relation torot, bitter rot, and white rotcan be problematic. bitter rot susceptibility/resistance. CultivarsIn general, these rots are more pervasive in the rated as moderately to very resistant by Dr. RomSoutheast than elsewhere, but one or more of include Jonalicious (Daniels), Jonadel, Jonagold,them can become a problem in almost any area if Winesap, Melrose, Red Delicious, and Romethe particular growing season is conducive. Beauty. Cultivars rated as moderately to very susceptible include Priscilla, Liberty, Elstar, A NEW ERA OF FUNGICIDES As many “old-guard” fungicides are phased out by environmental and health regulations, several new classes of chemistry are yielding safer, more ecologically sound replacements. The new classes of fungicides for perennial tree crops include DMIs (or sterol inhibitors), strobilurins, hydroxyanilides, pyrimidinamines, and phenylpyrroles. Some of these have broad-spectrum activity, but none are effective against all fungal pathogens of apples. Many are not at all broad- spectrum, but are highly effective against the pathogens they target. A defining characteristic of most of these new compounds is “single site mode of action” on the fungusin other words, the fungicide controls the fungus by disabling only one of its essential life-sustaining processes. This makes them radically different from familiar fungicides such as Captan, and means that they require a new way of thinking about and working with fungicides. This “new way” comprises some basic tenets of the IPM approach: more careful assessment of the targeted pathogens, including careful observation of their cycles in the orchard, more precise spray timing, and conscientious rotation of fungicides from year to year. Such measures are crucial both for achieving control with the new fungicides and for ensuring that the strains of fungi endemic to the orchard do not develop resistance to the chemicals. The new fungicides are not as environmentally persistent as are their predecessors, making them safer for workers in the orchard and for the environment. Compounds such as phenylpyrroles and strobilurins are photolytic, meaning they break down in sunlight. All of the new fungicides are degradable by microorganisms. Ecologically this is very good news. On the downside, it means that more frequent sprays will be necessary for good control. However, the newer chemicals are also generally effective at far lower use rates; for example, where 20 pounds per acre of sulfur might be typical, only 4 ounces of the strobilurin Abound will be needed, and will provide far better control. The importance of resistance management cannot be over-emphasized. Since many of these compounds have a single-site mode of action,the pathogen need undergo only a single genetic mutation, or possess a single genetic variation, to gain resistance to the fungicide. This means that rotation among several different fungicides must be the rule. Whereas before rotations between products was recommended, now rotations between classes of products is key. The risk of induced resistance is greatly diminished when growers know the class of each fungicide and rotate every time they spray. As always, better management and ecological dividends call for extra research and forethought on the part of the low-spray grower (43). Mutsu, Golden Delicious, Idared, and Stellar. // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 19
  20. 20. Williams Pride, Pristine, and Priscilla, generallyEd Fackler (42), an Indiana low-spray orchardist, escape sooty blotch and fly speck simply byhas noted that cultivars that ripen with ‘Gala’ virtue of their earliness.(about September 10 at his site) or earlier sufferlittle from the summer rots. Some cultivars that Where these diseases are problematic, most commercial orchardists use multiple sprays ofhave been reported to be especially prone to at fungicides through the summer for control.least one of the summer rots include Liberty, University of Georgia research indicates thatEmpire, King David, Priscilla, Golden Delicious, between 6 and 10 sprays of Captan will beFreedom, Wolf River, Rome Beauty, Jonathan, necessary most years to control these disorders.Blushing Gold, and Sir Prize. Other cultivars that Dr. Dan Horton (46) at the University of Georgiaseem to suffer little from the summer rots include is part of the research team that conducted low-Stayman, Arkansas Black, Dayton, Gala, Melrose, spray apple research under a 1988 LISA grant.Akane, and Fuji (42, 10). They relied on a post-harvest soak (1:100 parts household bleach to water) for sooty blotchFor control in low-spray and organic orchards, control. The apples were left to soak for 15growers should emphasize cultural techniques minutes, rinsed, and allowed to dry. Post-for suppression of the causal organisms of these treatment residue analysis showed less than 100rots. Such techniques would include pruning out ppm hypochlorite (bleach) residues on the appleof diseased wood, removal of fruit mummies, skin, and no residues in the flesh. Growers inpruning for light penetration and air circulation, other states should check with their stateand avoidance of poor sites. departments of agriculture for information on the registration status of this method.Captan appears to be the most effectivesynthetic for summer rot control (41). Dormant The sooty blotch/fly speck problem provides onesprays of the copper and sulfur fungicides can example where education of consumers,reduce the overwintering inoculum of the especially a particular clientele, can allow for asummer rots. For in-season protection, sulfur reduction in pesticide sprays. Orchardist Carolynsprays can be effective, but sulfur applications Ames (11) reports little or no consumer resistancemade when temperatures exceed 90°F. can cause to apples with sooty blotch and fly speck whenleaf burn. The finely ground, liquid formulations she markets at the Fayetteville Farmers’ Marketseem to be the least damaging in this regard. in northwest Arkansas. She attributes this mostly to the fact that she provides taste samples to herSooty blotch and fly speck clientele, and taste then becomes the primary purchasing motivation.These two fungal diseases are almost always If buyers do ask about the sooty appearance offound together even though they are distinct the apples, she explains that the fungi arefrom one another. The effects of both diseases are completely superficial, do not hurt the apple oralmost purely cosmetic but can render the fruit the consumer, and would otherwise have to beunsaleable in the conventional market-place (44). controlled by fungicide sprays up to harvest. She finds that most customers are completelyAgain, there appears to be no resistance, per se. reassured by her explanation, and expressHowever, these diseases are less apparent on appreciation of her ecological growing methods.darker fruit; yellow fruit seems to emphasize theproblem. Because the fungi are takingnourishment on the waxy surface cuticle of the The rootstock factorapple (45), very waxy types can be more prone tothese diseases while cultivars with little Apples can be grown on a variety of rootstocks,waxsuch as the russets (Roxbury Russet, which can be divided into seedling and clonalGolden Russet, etc.)may be little bothered. (genetically identical) types. Clonal types can beAlso, very early-ripening cultivars, such as // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 20
  21. 21. further divided by size into dwarf, semi-dwarf, Matching the right rootstock to the growersand semi-standard. management plan (especially considering pest control, site, and water) is a very importantThere are currently about eight apple rootstocks decision that could ultimately make thein common commerce, designated (in order difference in success or failure. Consultationfrom the most dwarfing to the least dwarfing) with the state Cooperative Extension horticultureM.27, M.26, M.9, Mark, M.7, MM.106, MM.111, specialists is recommended.and seedling. Each has its respective strengthsand weaknesses, many of which may impact MAMMAL AND BIRD PESTSpest control. Mammals are often overlooked by the beginningGenerally speaking, the smaller the tree the easier orchardist as important orchard pests, but deerit is to spray. A study at New York State and volesthe two most important mammalAgricultural Experiment Station indicates that pestscan easily put a young orchard out oforganic insect control in a dwarf orchard would commission in one short season. Fruit-eatingcost approximately $314/acre compared to$1200-3700 for an orchard on seedling birds are usually more troublesome on smallrootstocks (47). fruits (grapes and berries), but can cause serious economic damage to apples. For information onHowever, dwarfing rootstocks are not without controlling mammal and bird pests, see thesignificant pest problems. M.27, M.26, and M.9 ATTRA publication Overview of Organic Fruitare quite susceptible to fire blight. M.27, M.26, Production.and MM.106 are susceptible to phytophthora rootrot. All of the size-controlling rootstocks exceptthose with the “MM” designation are susceptible Farmer profile:to wooly aphids. Most seedling rootstocks are Tim Bates, The Apple Farm, Philo, Californiasusceptible to wooly aphids also, but are more Northwest California’s Mendocino county has atolerant of wooly aphid feeding damage than the higher percentage of organic farmers than anymore dwarfing rootstocks. other county in the U.S.some 12 to 16% of its growers are organic. Tim Bates, who has farmedFurthermore, there appears to be a general here for the past fifteen years, tends fifteen acrescorrelation between intensity of dwarfing and of apples, an acre of pears, some peaches, plums,non-pathogenic disorders such as chronic and quince. He converted to organic in 1987 andnutrient deficiencies or toxicities. As an example, is certified by the CCOF (California Certifiedall rootstocks the size of Mark and smaller are Organic Farmers).susceptible to apple measles, a manganesetoxicity problem. Most nutrient problems related The codling moth, which emerges in mid-April,to dwarfing can be taken care of with careful is Bates’ most worrisome insect pest. Damage toattention to soil fertility and pH. the apple crop can range from 6−13% each year. Bates relies on a varied set of tools to control theBorers can be a problem for any rootstock, but mothincluding sticky traps to monitor damage,the more vigorously growing rootstocks (the mating disruption through pheromones, andlarger ones) have considerably more tolerance release of predatory trichogramma wasps.for damage than less vigorous stocks. Dwarftrees require more frequent watering thanlarger trees. If allowed to become droughtstressed, dwarf trees are much more susceptibleto serious damage from borers than arelarger trees. // ORGANIC AND LOW-SPRAY APPLE PRODUCTION Page 21