In the San Joaquin Valley, Mating Disruption of Codling Moth Has

In the San Joaquin Valley. . .

Mating disruption of codling moth has mixed results

Walter J. Bentley o Lewis B. Sherrill o Allison Mclaughlin

Pheromone confusion had to be aug- ruption as a method of pest manage- mented with insecticide sprays to control Pheromone confusion worked codling moth in the Sherrill orchard, best in isolated orchards with low ment. In trials to date, this technique which has a history of long moth flights codling moth populations. In ar- has been more successful in some ar- and high infestation. eas where codling moth devel- eas than others. In addition to a climate that permits oped three to four generations Probably the most challenging situ- ation for mating disruption is the one extended flight activity of codling and apples were exposed to egg in which codling moth can develop a moth, this area provides hosts for co- laying for each generation, mating maximum number of generations dur- dling moth development throughout disruption with pheromones was ing a season. This is precisely the situ- the spring and into the fall. The pri- not consistently successful in ation in the southern San Joaquin Val- mary apple variety, Granny Smith, re- suppressing codling moth popula- ley. Based on an 11-year history of quires at least 180 days from full tions. For an orchard with an es- daily codling moth monitoring in the bloom to harvest. Another popular tablished history of codling moth Sherrill orchard near Arvin, California, apple in the San Joaquin Valley, the infestation, well-timed insecticide the total number of degree days (dd.) Fuji cultivar, is harvested even later sprays had to be integrated with between first and last moth of the year than Granny Smith. the confusion technique to obtain has ranged from 3,405 (110 moths per This article reviews mating disrup- adequate control. trap per season in 1983) to 4,694 (394 tion trials performed at three locations moths per trap per season in 1992).A in the southern San Joaquin Valley. degree day is defined as 1 degree The participating growers referred to Codling moth, Cydia pomonella above the threshold temperature for below include the Sherrill orchard (Linnaeus), has been a serious pest of 24 hours. This is using a base of 50 F trial, the Bidart orchard trial, the sec- apples and other deciduous fruit in and an upper threshold of 88' F. Moni- ond Sherrill orchard trial and the Met California since 1872. As fruit produc- toring traps were either Pherocon 1C West trial. The work was done by the tion moved into the San Joaquin Val- (1983-1989)) or 1CP (1990-1993) traps authors in collaboration with the grow- ley, so did codling moth. It still ranks baited with Trece 1 mg pheromone ers and their pest control advisors. as the key pest of apples. caps changed monthly. The earliest The sites were chosen based on the Until recently, the only ways of re- moth activity recorded was on March history of infestation. Both the Sherrill ducing infestation were through syn- 7, 1986, and the latest moth trapped orchard and the Met West orchard thetic insecticides (initially arsenicals, was on October 2,1991. Codling have a long history of high moth then chlorinated hydrocarbons, orga- moths are capable of laying eggs for as flights and infestation. The Bidart or- nophosphates and insect-growth regu- long as 7 months. In this area three full chard is a relatively new planting with lators) or through cultural methods, generations were present each year; low numbers of moth flights and no such as sanitation and larvae-trapping. most years had at least a partial fourth damage. It should be pointed out that However this approach has led to generation. A full fourth generation both the Sherrill and Met West or- problems with insect resistance and, in was possible in 1986 (3,981 dd.), 1990 chards, where mating disruption was some instances, pesticide residues on (4,013 dd.), 1991 (4,220 dd.) and 1992 in place, were also treated with insecti- fruit at harvest. (4,694 dd.). This is based on an aver- cides, but much less frequently than in However, with the isolation of age of 1,060 dd. for the first generation the conventional grower-sprayed codlemone in 1971, the synthetic sex and 1,220 dd. for the remaining gen- plots. This was not done at the Bidart pheromone for codling moth, has erations (a total of 3,500 dd. would al- location because we knew the moth come the development of mating dis- low for four generations). population was low. The use of some

CALIFORNIA AGRICULTURE, NOVEMBER-DECEMBER 1994 45 insecticide is necessary where moth ent per acre in 200 gallons per acre) Overhead sprinklers reduce the effec- populations are established and har- and July 31 (carbaryl at 3 pounds a.i. tiveness of insecticides and are a com- vest of apples occurs in late August per acre in 200 GPA), infestation at mon method of irrigation in the south- and September. The trial is a con- harvest, on September 4 (first pick), ern San Joaquin Valley. trolled trial that is intended to be ana- averaged 17.5%.On September 22 In 1992 and 1993 trials were at- lyzed statistically based on a number (second pick) damage was 33%. Both tempted again at the Bidart Granny of years’ research. In each trial, the of these infestation rates were com- Smith orchard, the Sherrill orchard pheromone disruption area was under puted using a random sample of 900 (for the second time), and the Met control of the researchers, while the fruit taken from throughout the or- West orchard. These trials were part grower and pest control advisor made chard. At that time an average of 62 of a long-term study to evaluate mat- decisions in the conventional plot. moths per trap had been captured in ing disruption; to date they have met the disruptant side (based on four with varying success. The Met West Sherrill orchard: the first trial Trece Pherocon 1C traps baited with orchard trial - where codlemone The first codling moth mating dis- the 1 mg codlemone-loaded rubber was used with least success - is dif- ruption trial established in Kern septa). ficult to evaluate, because the grower County in 1987 was not successful. It The standard insecticide compari- was late in placing disruptant in the was performed on the original 18.4- son block was sprayed three times field, contrary to manufacturer’s acre Sherrill orchard, which was with azinphosmethyl on April 15, June instructions. planted in 1981. The orchard has a 5 and June 20, at the rate of 1 pound Greater success was obtained in the density of 1,361 trees per acre (4-feet- a.i. per acre applied in 200 GPA. Car- Bidart and Sherrill orchards, where the by-8-feet spacing) and is irrigated by baryl was applied once, on July 31, at pheromone disruptant was placed in overhead sprinklers. The trees at the the same time and rate that was used accordance with manufacturer’s start of the season are approximately 6 in the disruptant-treated area. Codling (Consep) instructions. Three applica- feet high and at harvest are approxi- moth damage in the standard insecticide tions of disruptant were applied at ap- mately 9 feet high. Other than block averaged 3.7% on September 4. proximately 60-day intervals through pollinizers and a small planting of There were no fruit left after this date. the growing season in each of these lo- akane apples, a Japanese variety no cations. Even so, the success rate in longer grown in the orchard, Granny Bidart orchard trial these two orchards differed, possibly Smith was the only variety. To the The three experiments were all de- because they have quite different cod- west of the orchard is a 9-acre planting signed with a minimum of 5 acres ling moth histories. The Bidart trial of apricots, which are harvested by treated with the Checkmate. The has been quite successful. Where mid-May. To the east is a 10-acre grower standard plots were adjacent sprays were integrated with the phero- planting of peaches and nectarines, to the pheromone treatment and var- mone placement at Sherrill, it is also also harvested during May. No other ied in size as indicated below. The va- successful. hosts are within a mile of the orchard. rieties sampled were the same. Irriga- The Bidart Granny Smith orchard The pheromone-treated portion of tion was by overhead sprinkler at the site has been the most successful ex- the orchard was the east 11.5 acres; the Bidart and Sherrill orchards and by ample of mating disruption of the standard insecticide comparison block ground misters at the Met West side. three orchards studied. It was ob- was the west 6.9 acres. Following the served in both 1992 and 1993. Except manufacturer’s instructions, Biolure for the grower 32-acre standard com- LTD 6-month dispensers were placed parison site, adjacent to the phero- in the 11.5-acre area at a rate of 100 per mone-treated 6 acres, this orchard is acre on March 23, 1987. By April 10 isolated from any other codling moth flight of winter moths was detected in source and was in its second year of the disruption block, only 12 days af- production in 1992. The total 38 acres ter moths were trapped in a non- is surrounded by a small manufactur- pheromone-treated comparison block. ing area, airport, and canal to the This was a clear indication that mating south and a canal and vineyards to the disruption was failing. Fruit infesta- north and east. Open cotton land lies tion was first detected on May 8; by to the west. The orchard consists of June 12,12% of the Granny Smith 518 trees per acre on 6-foot-by-14-foot apples were infested in the phero- spacing. A modified Lincoln trellis mone-treated area. This was based on system is used. Trees are irrigated a small, randomly selected sample of with overhead sprinklers and are 100 fruit from throughout the approximately 12 feet in height at disruptant-treated area. Although two -_X harvest. sprays were subsequently applied to 9 In 1992 two standard ICP traps the disruption block on June 20 9 baited with 1 mg Trece caps were used (phosmet at 4 pounds active ingredi- Codling moth damage to monitor moths in both the 6-acre

46 CALIFORNIA AGRICULTURE, VOLUME 48, NUMBER 6 and a 10-acre portion of the 32-acre overwintering, first generation and a the overwintering flight based on the block. No codling moths were trapped portion of the second generation of co- 10 mg trap loads in both blocks). Ide- and no sprays applied to the 6-acre dling moth. ally no moths should be trapped in the disruptant portion of the orchard. The The history of the older orchard disruptant treatment, even using 10 disruptant was applied on March 27, area is of high codling moth popula- mg trap loads. May 20 and July 23 at the rate of 120 tions, based both on moths trapped Checkmate dispensers per acre. These during the season and fruit infestation Met West contain 105 mg active codlemone per found at harvest. For example, in 1992 A third site (Met West) was fol- dispenser. The grower-standard com- an average of 394 moths per trap per lowed in 1992 and 1993. The results parison trapped only four moths all season (Trece caps and traps) were observed at this site are difficult to season. One spray was applied on monitored from March 19 to Septem- evaluate because of the late placemen April 3 to the 32-acre block using 1 ber 19. Damage at harvest averaged of the disruptant. The orchard is near pound a.i. of chlorpyrifos in 200 gpa. 7% on August 19, even after five the oldest continuous planting of This treatment was aimed at both cod- sprays had been applied. In 1990 and Granny Smith apples in the southern ling moth and oblique-banded 1991,206 and 259 moths per trap per San Joaquin Valley. In both years the leafroller. At harvest in the disruptant season were found, respectively. This disruptant was placed considerably a treatment, on August 10, only 0.15% was also in spite of six sprays (1990) ter the first moth was trapped. In 1992 (2,000-fruit sample) codling moth- and five sprays (1991) applied for cod- the first moth was trapped on March damaged fruit was found; 0.6% was ling moth. Because of this high resi- 13 and disruptant placed on March 27. damaged by oblique-banded leafroller. dent codling moth population, we In 1993 disruptant was not applied un- Other pest damage was less than 0.5%. were hesitant to use this orchard as a til 19 days after the first moth was The grower standard had no codling trial site in 1992. trapped on March 8. Two subsequent moth damage and 0.15% oblique- However, in 1993 we felt that the placements of disruptant were made banded leafroller damage. integration of well-timed sprays aimed each year at 60-day intervals and at This orchard was again evaluated at first-generation worms and place- the 120-trap-per-acrerecommended in 1993, using the same guidelines as ment of Checkmate at 160 dispensers rate. This Granny Smith orchard is irri- in 1992. The only difference in method per acre might be effective in reducing gated with under-tree misters and was that codling moth was monitored damage at harvest. Eleven and a half contains 518 trees per acre (approxi- with 10 mg Trece codling moth septa, acres of the older 18.4-acre block were mately 12 feet high). The orchard is changed monthly and placed inside treated with the 105 mg Checkmate surrounded by various varieties of the 1CP traps cleaned regularly. The disruptant at the rate of 160 dispensers apples, peaches and nectarines. Checkmate disruptant treatments per acre on March 24, June 2 and Au- Observations were quite different were made on March 7, May 28 and gust 1. In addition, three azinphos- in each of the 2 years at the Met West July 30. No moths were trapped in the methyl (1 pound a.i. in 200 gpa) sprays site. The 1992 trial (5 acres of single trap placed in the disruptant were also applied to the overwintering disruptant-treated adjacent to insecti- side. Only,six moths were trapped flight and aimed at first-generation cide treated) was quite successful, during August in the grower-standard worms on April 4, April 29 and May with only 2.2% codling moth damage treatment, which was treated on April 20. No other treatments were made af- at harvest (August 11) in the 8 with chlorpyrifos (1 pound a.i. in 200 ter May 20 in the disruptant side of the disruptant (Consep) treated 5 acres of gpa) for both codling moth and ob- orchard; three more were made on Granny Smith. The grower insecticide- lique-banded leafroller. No damage July 1 (azinphosmethyl at 1 pound a.i. treated 5 acres had 0.1% damage. The was detected in a 500-fruit sample in 200 gpa), August 3 and August 23 disruptant was applied after a total of from each block on August 24,1993. (both carbaryl at 2 pounds a.i. in 200 23 moths had been trapped, and the GPA) to the 6.9-acre grower standard area was therefore sprayed with 1.5 Sherrill orchard trials side of the block. Infestation in both pounds of azinphosmethyl at 200 gpa A more challenging site was the or- comparison blocks on July 28 was 2 to on April 3, 1992. The grower-standard chard described in the 1987 trials, the 3%.Fruit infestation increased dra- area also received this treatment plus 18.4-acreSherrill orchard. This site matically by August 31. Based on a 1.5 pounds a.i. of methyl parathion on was only followed in 1993. The grower 1,000-fruit harvest sample, the grower May 2,1992. had planted an additional 10-acre or- standard, with six sprays, averaged In 1993 the disruptant treatment at chard in 1988, to the east of the origi- 7.2% infestation from codling moth Met West failed, resulting in 48% fruit nal Granny Smith planting. These two (no other damage) and 5.4% in the damage, in spite of the application of orchards were separated by a poplar disruptant-treated portion of the or- two sprays. These two sprays included windbreak. This new planting con- chard (stinkbug and oblique-banded 1 pound a.i. of azinphosmethyl on tained a mixture of Red Clapp and leafroller were less than 1%). An aver- April 4,1993 and 2 pounds a.i. of me- Bartlett pears and Gravenstein, Lady age of 387 moths per trap per night thyl parathion on August 12,1993. Williams, Mutsu and Gala apples. were trapped in the grower-standard Both treatments were in 200 gpa. The These fruit are all harvested by the area and 54 moths per trap per season grower standard received six sprays, end of July and exposed to only the in the pheromone-treated area (43 in all applied in 200 gpa. These sprays in-

CALIFORNIA AGRICULTURE. NOVEMBER-DECEMBER 1994 47 cluded 2.5 pounds a.i. of diazinon on April 6, 1 pound a.i. of azinphosmethyl on May 17,1.5 pounds a.i. of azinphosmethyl on June 4,0.75 pounds a.i. of methyl parathion on June 28,3 pounds a.i. of phosmet on August 4 and 1 pound a.i. methyl parathion on August 14. Infestation in the grower check was 6.4%at harvest on August 23,1993, also considerably higher than the previous year. Best uses, limits of pheromone Two extremes in codling moth infestation have been tested with pheromone disruption in the southern San Joaquin Valley. Where the orchard is young and the history of damage is quite low, pheromone confusion has worked alone and can possibly keep infestation from developing in the fu- ture (the Bidart orchard will be followed in the years to come). Where the history of infestation and moth populations is high, pheromone confusion must be supplemented with well- timed insecticide sprays, to be confi- dent of reduced codling moth damage at harvest. Our experience has been that treatment of first-generation In orchards where codling moth populations are high, mating disruption can reduce worms is the most successful ap- the number of insecticide sprays needed, particularly near harvest. proach. In spite of the insecticide treatments being required where codling tance to them. Repeated use of phero- Kern County Cooperative Extension; moth populations are high, mating mone mating disruption may eventu- and L.B. Sherrill is an apple grower, confusion has been observed to reduce ally lead to a decline of codling moth Arvin, California. the number of sprays necessary, par- populations in the orchard, unlike the The authors wish to express their ticularly those applied near harvest, increase seen during the last decade, thanks to Jim Eyherabide of Bidart Bros. when chances of finding detectable in spite of increased insecticide treat- Farming, Norm Reirmers, and Sam levels of residues on fruit are highest. ments. Perez of Met West Farming Corp. Also, Mating confusion can also be used to we appreciate the financial and product reduce the exposure to multiple appli- W.J.Bentley is Regional IPM Advisor, support of Consep Corp. The research cations of organophosphates and Kearney Agricultural Center, Parlier; was funded through USDA Coopera- thereby slow the development of resis- A. Mclaughlin is Laboratory Assistant, tive Agreement No. 91-COOP-1-6590.

CALIFORNIA AGRICULTURE ASSOCIATE EDITORS

Animal, Avian, Aquaculture Land, Air & Water Sciences and Veterinary Sciences J. Brian Mudd Richard H. McCapes Garrison Sposito (2nd assoc. editor to be announced) Henry J. Vaux, Jr. Economics and Public Policy Natural Resources Harold 0. Carter Daniel W. Anderson Alvin Sokolow John Helms Richard B. Standiford Food and Nutrition Barbara Schneeman Pest Management Eunice Williamson Michael Rust Human and Community Development Frank Linda M. Manton Plant Sciences Karen P. Varcoe Calvin 0. Qualset G. Steven Sibbett 48 CALIFORNIA AGRICULTURE, VOLUME 48, NUMBER 6