Pickel, Carolyn

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I. Mating Disruptiona. Implementation1. Oriental Fruit Moth and Peach TwigBoreron Cling PeachesCarolyn Pickel, Area IPM Advisor142-A Garden HighwayYuba City, Ca 95991Project Leaders: Janine Hasey, Farm Advisor-Sutter/Yuba Cos. and BillOlson, FarmAdvisor- Butte Co.There are two key insect pests in the cling peach orchard system Oriental fruit moth (OFM) andpeachtwigborer (PTB). Commercial products for controlling OFM withpheromone confusion have beenavailable since 1989. About 20% ofthegrowers have been using pheromone for OFM control. Manygrowers have been reluctant touse OFM mating disruption since they stillhadto spray for PTB,increasing theoverall cost ofcontrol. In 1995, thefirst commercial PTB product forpheromoneconfusion became available. The goal ofthis project is to introduce mating disruption togrowers andtodemonstrate a complete mating disruption program inan effort toexpand adoption andresult in areduction of insecticide.In this first year of the project therewere 16cooperators with 10in Sutter/Yuba and 6 in ButteCountiesrepresenting 155 acres. Growers were encouraged towait for first moth tomake the first application ofboth OFM andPTB pheromone. Growers first application ofOFM was typically aroundMarch 1st, andPTB around April 1st. This date varied for each grower since itwas based on first trap catch and weatherconditions. The secondapplication typicallywent up aroundJune 1st and was for bothOFMand PTB sogrowers would not have tomake a separate application a few weeks later for PTB. Following this protocolthesecond PTB pheromone application could be early. Growers in theprogram used all three commercialOFMproducts including Isomate, Checkmate, and Hereon. Themanufacturesrecommendations for theapplication rate andlength ofproduct were followed. Although, growers were encouraged to putthepheromone high in the treecanopy, approximately two-thirds upin the tree, notall of them followed thisrecommendation andpheromones were oftenin the lower parts ofthe tree canopy.Methods:Demonstration blocks were around 10 acres, in size, however, growers with small acreage were alsoincluded intheprogram. Whenever, possible, a nearby "grower standard" was used for comparison.Weekly trapcatches were started topinpoint thebiofix andcontinued throughout theseason forbothOFMandPTB. Shoot strike counts were made in eachorchard at theendofeachgeneration andcoincidedwiththeBiofix of the next generation. Thiswasdone bycounting total shoot strikes from 5 treesin eachblock. Each shootstrikewascutout and examinedfor liveworms and species determination. Harvestdata was completed bycollecting a total of 500 fruits from each variety in groups of 100 from differentlocations in the orchard. Growers were asked tokeep track ofpheromone application costs and spraycosts from thenearby commercial standard. This was done toget an idea of pheromone application costsand compare costs to a sprayed orchard.Results and Conclusions:There were problems with mating disruption for OFM this year and the pheromone traps were notadequate to predict this failure. Most ofthe growers that had to spray because ofthis failure had caughtnothing in the traps in pheromone blocks. After the shoot strikecountswere conducted at the end of the1st generation ofOFM (6/20), all orchards and blocks with over 5 shoot strikes per tree were sprayed.This included both experimental blocks, several orchards with Hereon pheromone, andseveral orchardswith Consep pheromone. Inthe month ofApril and May growers using Hercon's OFM product hadproblems with itblowing out oftrees. This pheromone was replaced by the company with a new productusing the same "bread clip" used on their PTB product inMay. One grower that continually replaced the73pheromone inthe April during the heavy wind storms didnot have tospray. The experimental blockcomparing Hereon, Consep, and UCD paraffin emulsion hadtospray out allthree products. All 3products tested were placed low inthe tree canopy. All the blocks that had tobe sprayed had high OFMpopulations in trap catches. Growers that did not have to spray hadlow damage forboth OFM andPTBexcept for the2blocks oflate variety Sullivan. Inthe second Sullivan block damage was ontheoutsidetrees indicating migration intothe orchard. Theonly damage in most blocks was fromleafrollers.It iseasy to explain the failure ofHereon pheromone since itwas blowing out ofthe tree. On examiningthe trees only one-quarter of the pheromonewas left in the tree. This allowed almost one months timewithout adequate rate ofpheromone. This has been remedied by Hereon changing tothe bread clip, whichwillnotblow outin strong windstorms as it did thisyear.The Consep pheromone failure was more difficult to explain. Some researchers feel that 19 grams peracre of OFM pheromone isnot adequate for high population orchards. Dr. Rice felt that it isimportantfor the pheromone tobeplaced high inthe tree. He also theorized that the unusually cool nights thisspring were not allowing the pheromone tovolatilize upinto the tree increasing the importance ofpheromone placement high in the tree.The PTB pheromone program was more successful, although thePTB populations were overall lower thisyear. When conducting shoot strikes we did see a few PTB worms, but we did not see any damage atharvest. Two demonstration blocks were onyoung trees known for being attractive toPTB. One block init second leaf used HereonPTBpheromonehad no shoot strikes and the secondblock in its third leafhad lessthan strike per tree(0.4) and hadnoPTB damage at harvest.Our future recommendations arethatgrowers new tomating disruption with high OFM population needtouse a product with a higher load rate like Hercon's OFM with a rate of 27grams andIsomate (400 peracre) at 30grams. Once growers OFM populations are reduced from using mating disruption fora fewyears theywillbe able to use lowerrate products ofpheromone. Wewill also recommend that thepheromone be placed high in the tree.Preliminary results onapplication costs shows thefirst application with 11 growers reporting averaged$12.98 peracre. The second apphcation which was for PTB with 10 growers reporting averaged $11.35peracre. Andthe last application withboth OFM andPTBaveraged $25.98 peracrewith4 growersreporting. Forall 3 applications the range was from $3.60 to $42.97. A total application costperacreaverage was $50.31.Wealsomade general observations about thedemonstrations blocks. Wealsoobserved that growers in theprogram hadmore powdery mildew because theyare notapplying regular fungicides in their cover sprays.Wewill recommend that growers makean application for powdery mildew at petal fall or theycanuseafungicide suchasBenlate or Topsin that controls powdery mildew fortheir second brown rot spray. Ifmildew conditions suchas cool nights andovercast skies persist, a second application in lateApril withwettable sulfurwillbe recommended formildew and rust control. Although, thereweresomeproblemsin some orchard using mating disruption in 1995. Overall these 16demonstration plots show a completemating disruption system is now possible.74

Oriental fruit moth and peach twig borer on cling peaches

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Oriental fruit moth and peach twig borer on cling peaches

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