Contents: By Damage and Image
Peach Tree Borer Mating Disruption Brochure
Mating disruption of peach tree borer, Synanthedon
exitiosa: use of an alluring fragrance leads to a bad date for a peachtree
The strategy is relatively simple . . . overwhelm him with perfume. So much perfume, he doesn't know from whence the intoxicating aroma emanates. Her pheromone trail, designed to be a single beacon on which to hone, is hidden by a diffuse bombardment of scent, leading him everywhere and nowhere at the same time. If he can't find her, they can't mate. No mating, no eggs, and no future generations of moth larvae. Such is the devious scheme behind the mass release of insect pheromones known as mating disruption.
The most prevalent use of mating disruption in nursery
crops in the Pacific Northwest is targeted at peachtree borer, Synanthedon
exitiosa, in Prunus shade tree production. Several growers
in the North Willamette Valley in Oregon have adapted the practice from
recommendations for commercial Prunus fruit orchards. They report good
success, often completely reducing the need to chemically treat and suffering
few losses to this clearwing moth borer.
Confusing peachtree borer males can be remarkably easy even for beginners. There are several very simple steps. First one must know when the males are on the prowl, measuring their flight with pheromone traps. Traps need to be hung low within three feet of the ground and spaced with at least one trap for every 2.5 acres. Traps should be placed at the beginning of adult emergence, usually in mid-late June. They should be monitored through the flight period, possibly through the end of September in the Willamette Valley. Research in central Georgia found the most significant flight period was in August and September when 80 percent of the adults emerge (Snow, 1990) but trials in British Columbia and Utah show early activity by July and mid-June respectively (Alston et al. 2003). The pheromone lures are volatile and need replacement every 4-6 weeks depending on the temperature (they release faster at high temperatures). Then the mating disruption dispensers are placed in the plantings prior to the flight period. The recommended rate is 100 dispensers per acre. The dispensers are long twist-ties which are simply tied around a twig in the middle third of the canopy. Best results are achieved by treating blocks of at least five acres but work in one-acre block trials in commercial peach orchards in Utah and 2.5 acre blocks in New York also showed trap shutdown and complete control of peach tree borer. The pheromone dispensers, unlike the pheromone lures in the traps, should last an entire summer flight season.
We recently implemented a mating disruption trial working with the assistance of Glenn Thayer at Pacific Biocontrol Corporation. In late May diamond traps with peachtree borer pheromone lures (Pherotech International) were set in five-acre block of Prunus laurocerasus in a commercial nursery site with a history of PTB infestation. In June Isomate®-P pheromone dispensers (Pacific Biocontrol Corporation) were placed in the upper canopy of the laurel plants at the recommended rate of 100 dispensers/acre.). The traps, both in the mating disruption treatment area and in laurel plots outside of that area, were monitored weekly from June 2nd until the end of the flight period in September.
Day fliers, two male moths caught the eye but eluded capture in early June (6/2/06) and the traps remained empty of peach tree borers until four moths were found in three separate traps outside of the treated area on August 8th. This was above the recommended action threshold developed for mature fruit orchards of 2 moths/trap and Pacific Biocontrol recommends treatment at this level. The grower treated both the mating disruption and non-disruption control plots on August 10. Traps provided an additional catch on August 22nd with two moths tangled but still alive in our trap from a plot 1633 feet distant from the mating disruption. Above threshold again, the grower treated all plots the next day. He made an additional application on September 11 on the advice of an agricultural crop consultant. Our traps remained empty through the end of the sampling in late September.
Presumptuous to speak of results so early in this experiment but the trends are positive. The only peachtree borers caught, were caught away from the mating disruption treatment plot. In the year prior, a pheromone-baited trap in the treatment area was coated with peach tree borers. As peach tree borer eggs laid this summer, will only yield noticeable damage and larvae next summer, time will judge this strategy with more scrutiny. But from a beginner's point of view . . . implementing mating disruption was extremely simple. Most of us can hang a few sticky pheromone traps and check them weekly for a few months during the summer. The dispensers are easy to apply, simply requiring gloves as PPE with no re-entry issues. This tactic is also compatible with existing pest management programs.
This strategy requires use of pheromone traps, emphasizing the importance of monitoring pest populations and targeting action based on pest activity versus calendar sprays at regular intervals. That itself can greatly improve the timing of control activities. Successful mating disruption can greatly reduce PTB pressure, often eliminating chemical intervention. Eliminating cover sprays also helps to preserve populations of beneficial insects and mites in the system that otherwise are impacted by insecticides. Pulling off cover sprays may also highlight secondary pests previously controlled with broad spectrum insecticides. In laurel, leaf feeding caterpillars such as carnation tortrix may become more apparent.
Several local agricultural product suppliers provide both dispensers, the monitoring traps and pheromone lures for growers making access to mating disruption readily available to Northwest growers. Research from other mating disruption trials such as those with codling moth in apples and pears shows the benefit of having contiguous growers using mating disruption, increasing the suppression of moth populations over a regional basis. Reducing pest pressure is a very neighborly act.
If you have experienced losses to peachtree borer, consider your options. The scent of a female PTB, in the right hands, can knock a male off kilter, achieving dramatic results and the sweet smell of success.
Alston, D.G., M.E. Reding and C.A. Miller. 2003. Evaluation of Three Consecutive Years of Mating Disruption for Control of Greater Peachtree Borer (Synanthedon exitiosa) in Peach. Proceedings of the 77th Annual Western Orchard Pest & Disease Management Conference. Portland, OR.
Snow, J.W. 1990. Peachtree Borer and Lesser Peachtree Borer Control in the United States. In: Behavior-Modifying chemicals for Insect Management/ editors: R.L. Ridgway, R.M. Silverstein, and M.N. Inscoe. Marcel Dekker, Inc. New York.
Yonce, C.E. and C.R. Gentry. 1982. Disruption of Mating of Peachtree Borer. In: Insect suppression with Controlled Release Pheromone Systems/ editors: Kydonieus, A. F. and M. Beroza. Boca Raton, Fla. CRC Press, vol.1.
Acknowledgement: The authors would like to thank our
cooperating grower; Glenn Thayer and Pacific Biocontrol Corporation; and
the ODA Nursery Research Grant Program for their assistance and support
for this work.