Washington State University Cooperative Extension

Areawide IPM Update

The Newsletter of Pheromone-based Orchard Pest Management

Vol. 2, No. 6 -- May 1, 1997

Cooperating agencies: Washington State University, Oregon State University, University of California, U.S. Department of Agriculture, and Chelan County.

Cooperative Extension programs and employment are available to all without discrimination.

Monitoring codling moth with pheromone traps

Codling moth have been monitored for nearly twenty years in orchards using traps baited with pheromone emitting lures. The moth catch information has been used to both time sprays and to determine the need for treatment. Many improvements in the trapping technique have been made and several more are likely in the next few years, in both conventional and mating disruption blocks. As with any tool, proper use is essential to get the best results.

Conventional blocks

Lures: Several types of lures containing the CM pheromone are available commercially. The industry standard has been the red rubber septa (RR), containing 1 mg of codlemone. Research has shown that to ensure consistent attractiveness this lure needs to be changed every 3 weeks in the spring and every 2 weeks in the summer. Trece, Inc., one manufacturer of the RR, states that their lure in 1997 contains a new CM pheromone formulation that will provide consistent catch for a 4-week period.

There is considerable interest in using a lure that will perform at least as well as the RR, and require less frequent changes. Three other types of lures have been shown to remain attractive for at least 4 weeks and to catch as many or more than the RR standard: the Biolure (Consep, Inc.), a lure tape (Hercon, Inc.), and a gray rubber septa (several manufacturers). These lures also have the advantage of limiting the isomerization of the pheromone, a process that makes the lure repellent rather than attractive to codling moth. The Biolure and gray septa have been inconsistent in their performance in the cooler spring months, and further testing of these are planned in 1997. I encourage growers and consultants to test some of these products in comparison with the RR--and let me know the results!

Traps: A wing-type trap, like the Pherocon 1CP® or equivalent, has been the standard for most researchers and consultants in the West for many years. Proper use and maintenance is crucial to optimize catch and is often neglected. In conventional blocks, traps should be hung securely in the middle third of the tree height, not below head height, and near the outer perimeter of the canopy. If you want to determine biofix (the beginning of male flight) then traps should be in place before full bloom of Red Delicious apples. Check traps weekly after biofix. To maintain the stickiness of the trap bottoms, stir up the "stickum" periodically when it becomes fouled or coated with dust, and replace the bottoms when accumulated moth catch has exceeded 30 per trap or at the end of the first generation, whichever is first. Remember also to remove the old lures when the new ones are inserted.

Studies continue with other trap types. Some consultants use a delta trap, and replicated trials in 1996 showed that a large delta trap caught an equal or greater number of CM through the season than the wing trap. There is also interest in using the Multipher®, a plastic, non-saturating trap without a sticky surface that attracts moths inside, then kills them with an insecticide strip. This trap type is very easy to service, with no sticky surface to maintain. Trap catch with the Multipher® was not quite equal to the wing trap in 1996 trials, and research will continue in 1997 with modifications to the trap and the insecticide.

Mating disruption blocks

Lures: Monitoring with standard lures like the 1 mg RR is of little value in mating disruption (MD) blocks, as the high pheromone levels mask their attractiveness. The standard lures cannot be used to indicate whether sprays are needed to supplement the mating disruption. Instead, traps baited with a high-load red septa (10 mg of codlemone) have been used successfully to monitor CM where mating disruption is used. At this point, for consistent attractiveness they need to be changed at the same intervals as for 1 mg lures (3 weeks spring, 2 weeks summer). Research is ongoing with several other lure types that promise to be superior to the 10 mg RR, providing a more consistent and even higher attractiveness over a longer period. We hope to be able to recommend a better lure by next year, but for now the high load RR remains the standard in the CAMP sites.

Traps: The wing trap is the common choice in MD as well as conventional blocks, but their successful use varies in a few respects. To maximize catch, traps in MD blocks need to be placed higher in the tree canopy, within the top third of the tree. In a typical block with tree height of 12 to 14 feet, that would mean traps should be 8 to 9 feet from the ground. Many consultants and CAMP site managers use a four-wheeler (ATV), sometimes with a box on its rack, to stand on to reach the higher traps. An extension handle of bamboo or similar material may be attached to the trap wire for placement and removal from high limbs.

Trap numbers and interpreting catch

The number of traps needed per orchard depends upon your objective in trapping. If your only purpose is determining biofix for use with the codling moth phenology model, then placing a few traps near known hot spots may be enough. Check these traps daily, beginning shortly before full bloom on Red Delicious, until a consistent catch is found. More traps are needed if you want to follow CM flights through the season, monitor relative CM pressure through your orchard, and/or determine the need for sprays. Place traps in the block to represent all of the borders, staying at least two tree rows in from the edge, and through the block interior. Bias placement towards known or suspected CM sources and "hot spots."

Using higher densities of traps will give more accurate information on CM population levels and distribution. In conventional orchards, many consultants have found that using traps at a density of one per 5 to 8 acres has given them adequate catch data on which to base a control program. In MD orchards, traps attract moths over a smaller area, even with the use of high-load lures. Trapping in MD blocks should be at a higher density, with one trap per 2.5 to 4 acres in order to provide a similar level of accuracy. In the CAMP sites, with CM trap density averaging one per 2.5 acres, moth catch in the first generation has been similar in reliability to conventional trapping programs in predicting CM damage and the need for supplemental sprays. The reliability of moth catch declines in the second (summer) CM generation in both conventional and MD orchards, although considerably more in MD blocks. Research in 1997 will pursue reasons for and solutions to this problem.

The use of moth catch action thresholds to determine whether to spray has been used successfully for many years by growers and consultants. This approach is very dependent upon proper trap use and maintenance, and the density at which traps are placed. In MD orchards with traps at one per 2.5-3 acres, and in conventional orchards trapped at one per 5-6 acres, good control has been achieved with supplemental insecticide applications when cumulative CM catch reached 4 or more moths per trap. A more complete review of action thresholds can be found in the May 1996 Areawide IPM Update.

Trapping should be used together with visual inspection of fruit for codling moth damage, particularly within mating disruption blocks. Inspect at least 50 trees per block twice each generation. In the first generation, examine apples when hand thinning begins, and again in late June. These exams can help determine the need for and location of sprays, especially in the following generation. From the ground, concentrate your search on fruit in the upper canopy of the tree, along orchard borders, in known hot spots (like near bin or prop piles, the top of slopes, and near packing sheds), and on susceptible varieties like Golden Delicious.

Success®: a new insecticide for orchard pest management

Within the next few years we could lose many of the principal pesticides used for orchard pest control. Insecticides such as Guthion® and Lorsban® may be gone or their use severely restricted, mostly due to regulatory changes stemming from the Food Quality Protection Act of 1996. At the same time, we are on the brink of having registered some new insecticides, many from completely new classes of chemicals, that could prove to be vital components of our pest management programs. One of these is Success®, a new insecticide developed by DowElanco of Indianapolis, Indiana.

Success is a fermentation product derived from the actinomycete bacteria Saccharopolyspora spinosa. This microorganism was discovered by a DowElanco scientist inside a rum barrel in the Caribbean--a tough job, but someone had to do it! When the bacteria was cultured it was found to have insecticidal properties. These properties stem from the production of naturally derived active molecules called spinosyns, from which the compoundís proposed common name spinosad is derived. Spinosyns have shown good insecticidal activity against a number of insect orders, including thrips, beetles, caterpillars, wasps and flies. The spinosyns and their mode of action are unique and unrelated to any other available insecticides, making them valuable in a resistance management program. This insecticide acts quickly, with susceptible insects showing signs of poisoning within an hour or two and dying within a few days.

Success has many qualities that make it well suited for use in integrated pest management programs. It acts as both a contact and stomach poison, but is much more active if eaten. It has relatively short contact residual activity and degrades rapidly in the environment. It has some trans-laminar activity (absorbed locally into the leaf), which extends its activity against leaf feeders like leafrollers and accounts for its effect on leafminers. It is a relatively "soft" pesticide, having almost no activity against many beneficial insects, including lady beetles, lacewings, predatory bugs and predatory mites. An exception to this is its high toxicity to Hymenoptera, including honeybees and parasitic wasps. Dried residues, however, have little effect on bees, so this risk can be minimized by spraying when bees are not present. Some parasitic wasps, like the leafroller parasite Colpoclypeus florus, are more sensitive than honeybees, and research is continuing in Washington on the full impact of Success on them. It is practically non-toxic to mammals and birds, and somewhat toxic to aquatic organisms.

Success will be especially valuable for controlling leafrollers. Work by Dr. Jay Brunner with Success and the two principal orchard leafroller pests in the Northwest (pandemis and obliquebanded leafrollers) has shown it to be highly active against both species, even at rates as low as 0.04 lbs. of active ingredient per acre. Only 1 to 2 ppm were needed to kill 50% of first instar larvae in laboratory bioassays. Excellent control was obtained even when large larvae were treated in mid-summer field trials. Significant residual activity on neonate larvae was found up to 21 days after treatment, when higher rates were used. 1996 trials using air blast sprayers showed Success to be highly active against both spring and summer larvae, applied either as a dilute or concentrate spray. The single best timing appeared to be at petal fall, with much better control from this single application than with a delayed dormant Lorsban spray.

DowElanco expects to have Success registered for apples this year, perhaps by July, which could allow it to be used against the summer generation larvae that begin to hatch in late June or early July. If this registration is delayed, Success may first be used in apple orchards in the spring of 1998. Other new pest control procedures for leafrollers are or will soon be available, including leafroller mating disruption and the insect growth regulator Confirm®. With the introduction of Success and the continued use of existing controls, like Bts and Lorsban, effective leafroller control in orchards could quickly become a whole lot easier to obtain, and "softer" to boot.

Verify those secondary pest species: diagnostic support from WSDA available in 1997

New to CAMP in 1997 is a diagnostic service for secondary pest lepidoptera, via recently developed resources within the Washington State Department of Agriculture (WSDA). Eric LaGasa, State Entomologist with WSDA, received WTFRC grant funding to identify leafrollers from the CAMP sites. His laboratory in Olympia is willing to shoulder most of the work that would have fallen to the secondary pest sub-project, in terms of rearing and identifying leafroller species and preparing parasitoids. Essentially, Eric and his staff will do the rearing, specimen prep, identification, and summary reporting for all leafroller material collected, and the secondary pest project field staff will be responsible for collection and shipping to Eric's lab in Olympia. Additionally, Peter Landolt (USDA ARS YARL) will identify noctuids (cutworms and relatives) from CAMP sites reared in this project.

Identification of lepidoptera defoliators has been a focus of the WSDA Olympia laboratory for several years to support state surveys for introduced exotic pest species. A substantial reference collection and diagnostic expert resource network have been developed in the last three years, and are now available to CAMP.

Identifying defoliator larvae to species is difficult, if not impossible, without the appropriate resources; those resources have not been readily available in the Pacific Northwest previously. Accurate species identification is a critical aspect of any secondary pest research project.

Project specimen handling protocols and other diagnostic support details are available directly from Eric LaGasa at (360) 902-2063, or from Betsy Beers and Peter Landolt.

Ted Alway, Editor
Phone: (509) 664-5540
Fax: (509) 664-5561
e-mail: alway@coopext.cahe.wsu.edu

Partial Funding provided by: Washington State Tree Fruit Research Commission, U.S. Department of Agriculture-Agricultural Research Service.

WSU Cooperative Extension, Chelan County
400 Washington St.
Wenatchee, WA 98801

Wenatchee WA, 28 April 1997