The Newsletter of Pheromone-based Orchard Pest ManagementVol. 1, No. 10 -- November 1996
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Codling moth (CM) catch in pheromone traps, sprays for CM control, and CM damage are down at all sites. Pheromone dispenser rates were reduced in some blocks. Leafroller damage was, on average, at or below last yearıs levels. Secondary pest problems were insignificant.
In 1996, apple and pear acreage using mating disruption (MD) for codling moth control increased to close to 37,000 acres in the Western U.S., up from less than 28,000 acres the year before. In Washington state, acreage under CM MD increased from about 17,000 acres in 1995 to at least 22,000 acres in 1996. Discussions with growers, consultants and representatives of the two main pheromone dispenser manufacturers indicate that a sizable further increase in acreage can be expected for 1997.
The five CAMP sites are quite different from each other in many ways, including climate, topography, fruit varieties, pest types, pest pressure and more. Each faces a distinct challenge in using an areawide approach to pest management, with CM MD as the key feature of the program.
Let's review how each site fared in 1996:
This year both pests were well controlled. Codling moth fruit damage, already low in 1995 at 0.2% on average, declined further this year to only 0.06% at harvest. Cover sprays were reduced, with some blocks having no insecticides applied for CM. The release of sterile CM from the Sterile Insect Release program facility in Osoyoos, BC continued for a second year. The release of these sterile insects, combined with mating disruption and limited use of cover sprays, has drastically reduced CM populations in this formerly high pressure area. Releases took place from late June into September. For the sterile insect approach to be effective they shoot for a ratio of sterile:wild of at least 40:1. Last year, with a higher wild population, the average ratio for the season was 30:1, as found in pheromone traps. This year the ratio topped 180:1, reflecting the very low wild population in the area.
Leafrollers were well controlled within this CAMP site by use of a thorough early season monitoring and spray program. All growers applied a delayed dormant Lorsban and oil spray, and followed up with two or more Bt applications in the pre- and post-bloom periods, paying particular attention to getting good coverage of the foliage. Leafroller damaged fruit at harvest declined from an average of 1.0% in 1995 to below 0.5% this year. This year many growers in the Oroville area, outside the CAMP site, had leafroller problems for the first time. Leafroller fruit damage in the conventional blocks monitored for comparison averaged close to 0.9% in 1996.
In 1997, the Lake Osoyoos CAMP growers are considering further reductions in cover sprays and reducing dispenser rates in some blocks or block interiors. They hope to continue to use sterile moths from the SIR program, possibly making releases beginning with first generation CM flight, if supplies permit. There is interest in expanding the area under CM MD on the east side of the lake, extending it south from the CAMP site.
What actually happened was that first generation catch in pheromone traps was well below that of the year before (1.3 per trap vs. 7.4 in 1995). This drop in catch was repeated for the second generation (0.3 in 1996 vs. 1.4 in 1995), for an overall 80% reduction in catch. Cover sprays were also reduced from the year before, with many blocks getting only one treatment (and a few zero). Some growers even reduced their pheromone dispenser rates this year. Most importantly, extensive bin samples at harvest showed only 0.2% CM damage, down from 0.6% in 1995, and 0.9% in 1994, before the project began.
In 70% of the blocks examined, no CM damage was found. The one orchardist on the Flat who did not participate suffered between 10% and 20% CM damage, and served as an infestation source for his neighbors. Most CM damage was found near his orchard; if these adjacent blocks are not included, the average CM damage falls to 0.05%.
In the case of leafrollers, the populations on the Flat remained about the same as the year before. The number of leafroller pheromone traps used was doubled, with 107 each for pandemis (PLR) and obliquebanded leafrollers (OBLR). Fruit damage from leafrollers averaged 0.2% across Howard Flat, and tended to be concentrated in the areas having the highest leafroller pheromone trap catches. These troublesome hot spots persist, and the bin sample information is important for targeting early season leafroller control programs next year. Most growers responded to high trap catch in the first flight with summer sprays of Bt products, keeping pest control programs "soft" in an attempt to conserve natural enemies.
CM populations declined at this site also in 1996. Codling moth traps this year were placed high in the tree canopies, and the number of traps was doubled to a density of one trap per 2.5 acres, both changes designed to more accurately monitor CM populations. Trap catch of CM for the season averaged 2.7 moths per trap, down from 5.2 the year before. Cover sprays were down greatly in 1996, with an average of about one per block versus three the year before. Almost half of the site received no CM sprays in 1996. (In contrast, nearby conventional comparison blocks applied 5 to 6 covers for CM, as was done in 1995 as well.) Fruit damage in the CAMP blocks from CM was very low, on average equal to or below that of 1995.
In common with the other sites, the CM damage found was mostly from the second generation. Two blocks had CM damage above 0.6%, and neither block had a problem population in 1995. In at least one of these blocks this risk of CM damage was not indicated by trap catch Conversely, the hot spots in 1995 were cleaned up well in 1996. This serves as an example of the difficulty often encountered in reliably monitoring CM in MD blocks, particularly in the second generation. The blocks using the Checkmate-CM dispenser made a third application of this product in mid-August. Residual analysis of these dispensers by the USDA lab indicated that close to half of the dispensers had run out of pheromone at that time.
Pandemis leafroller proved to be more of a pest than codling moth for many growers. Several blocks developed high populations , with extensive fruit damage showing up at harvest. There was no real reduction in PLR populations from the previous year, despite a stepped up control program by some growers, using more Bts aimed at the overwintered larvae in the spring. Many are frustrated by both the difficulty of accurately monitoring for the larvae, and by their inability to get good control with their spray program.
Other orchard pests posed no serious problems in 1996. Pear psylla began and ended the year at lower levels in the CAMP pear blocks than in the conventional comparison blocks. Leafhopper and leafminer were not a problem either in CAMP or in the conventional blocks. Leafminer parasitism was similar in both areas although, in the absence of any treatments, leafminer populations were somewhat higher in CAMP. Aphids did receive more treatments this year in the CAMP blocks.
The Carpenter Hill CAMP site increased to 400 acres in 1996, with addition of 100 new acres that included apple blocks for the first time within this project site. Six growers are involved at this site. All growers use a "soft", selective control program on their pears, that centers around the use of oil and oil + lime sulfur applications before bloom, followed with foliar oil applications at 200°D, 400°D and 600°D after CM biofix. Pheromone dispensers (Isomate-C+ in this case) are applied by bloom. Finally, a Guthion application is recommended at 1250°D. The apple blocks do not receive the foliar oils, but do get a delayed dormant oil + Lorsban spray.
Codling moth was well controlled again in 1996, with only 0.04% fruit damage at harvest. Psylla and mites were also no problem within CAMP. Leafrollers remain a concern. Although fruit damage on average was low (0.3%), and lower than in 1995, leafrollers were concentrated in hot spots, sometimes in unanticipated new locations. Pests of increased concern were various true bugs, including lygus and stink bugs. Harvest time damage from these increased from 0.4% on average in 1995 to nearly 0.9% this year, with damage being much worse on Bartletts. Weeds and shrubs alongside the affected orchards are thought to be the source and more attention will be paid next year to monitoring and eliminating these "bug hotels".
Pest-caused damage in the CAMP blocks was similar to that in the conventional comparison blocks (both around 0.35% total on Bosc). In reviewing the 1996 season at this site, Laura Naumes, the site coordinator, pointed out the program's strengths of providing pest control as good as the conventional orchards and at a lower cost. Weaknesses at this time are in predicting CM damage, monitoring natural enemies and locating and controlling sources of bugs. Growers have identified many concerns, many in common with other CM MD users. These concerns include controlling CM on orchard borders; potential chronic effects of foliar oil applications over time on tree health and vigor; the cost of installing pheromone dispensers; possible gradual increases in apple rust mite and CM populations over time; and the need for intensive monitoring that this program requires.
After the third year they showed that they could achieve effective CM control, when MD was combined with organophosphate sprays. The amount of CM damage has been acceptable (0.2-1.0% on average) but the economics of the program has been questionable. Because of the high summer temperatures in this region, they felt they needed to make two applications of Isomate-C+ dispensers to maintain enough pheromone in the orchard, doubling the cost of MD and making it too expensive a control program.
In 1996, they reduced pheromone costs by applying a single application of Checkmate-CM (160 dispensers/acre) at bloom, followed 30 to 40 days later with an application of Isomate-C+ (400/acre), timed to coincide with the main peak of first generation CM flight. Control of CM was again good at Randall Island, comparable to previous years. Most growers supplemented the MD with one organophosphate spray, although there are a few blocks that received no cover sprays, some for several years now. Overall, 1996 appeared to be a lower pressure CM year, both for Randall Island and growers outside the project.
Leafrollers have not generally been a pest for Randall Island growers, but numbers have been creeping up over the years in the absence of any real control program. In 1996 leafroller numbers warranted some insecticide applications aimed specifically at them, and fruit damage did exceed 1.0% in a few areas. There were no problems with other secondary pests; mites and psylla seem to be well controlled with an abamectin application.
For 1997, Randall Island growers are considering moving to less expensive control program that includes only one application of Isomate-C+, applied after the beginning of first generation flight, supplemented with a single organophosphate spray timed for the main peak of first generation CM flight, about 600-700°D after biofix. The later dispenser application timing may provide sufficient pheromone to last into the post-harvest period. They feel one OP may be enough in most blocks, as CM damage has always remained below 0.5% in past years at Randall Island where at least one has been used.
The existing five CAMP sites will continue to receive financial support from the federal government for several more years. Also, the USDA-ARS has funding available to promote the establishment of new areawide control sites in the West. Funds will be provided, beginning in 1997, to several qualifying sites each year for a duration of one year, with an option of a second year. The money is to be used to hire the person (or persons) needed to do the monitoring, coordination and dissemination of information needed, and to provide for the needed traps, lures, field supplies and office supplies. At a recent meeting of CAMP researchers and coordinators criteria were developed for selecting new USDA-funded sites. These include:
To receive funding for 1997, proposals must be received by the USDA-ARS lab near Yakima by mid-November. Several proposals are expected by then from sites in both Oregon and Washington. The same program will be available for 1998 and, hopefully, 1999 as well. For more information contact Dr. Carrol Calkins at the Yakima USDA-ARS lab, (509) 454-6570, or Ted Alway with WSU-Cooperative Extension, (509) 664-5540.
Ted Alway, Editor
Phone: (509) 664-5540
Fax: (509) 664-5561
Partial Funding provided by: Washington State Tree Fruit Research Commission, U.S. Department of Agriculture-Agricultural Research Service, U.S. Apple Association, and U.S. Environmental Protection Agency
AREAWIDE IPM UPDATE
WSU Cooperative Extension, Chelan County
400 Washington St.
Wenatchee, WA 98801