2009 Annual Report

Pulling a delta trap high into the tree canopy to monitor codling moth flights.
Photo by Jack Kelly Clark.

Research and extension partnership leads to successful pheromone mating disruption for codling moth

by Carolyn Pickel, UC IPM and UC Cooperative Extension; Joyce Strand, UC IPM; Rachel Elkins, UC Cooperative Extension; Joe Grant, UC Cooperative Extension; and Steve Welter, UC Berkeley

Close collaboration between research and extension has been key to the success of IPM programs. As one example, UC IPM sponsored many of the research, application, and demonstration projects that have led to successful codling moth control by pheromone mating disruption (PMD) in California pears and walnuts. In doing the work, scientists often partnered with commodity boards and the USDA. The following timeline shows key events, occurring over four decades, that eventually led to adoption of new IPM methods.

• 1959: A. Butenandt identifies first sex pheromone.
• 1960: M. Beroza suggests mating disruption technique.
• 1971: W. Roelofs discovers codlemone codling moth pheromone.
• 1973: Zoecon starts selling codling moth traps that use codlemone lure.
• 1991: Pacific Biokontrol registers Isomate C, a hand-applied codling moth pheromone, for pears and walnuts.

Pear damaged by codling moth.
Photo by Jack Kelly Clark.

The Situation in Pears: In the 1990s, California pears became infested with Guthion-resistant codling moths, and growers needed a new technique for codling moth control.

• 1996: Combined research and demonstration using puffers to distribute codlemone in pears was initiated. (R. Elkins, H. Shorey [UC])
• 1996-2009: UC farm advisors extend puffer technology to growers.
• 2009: Impact—95% of pears in California are under pheromone mating disruption.

The current puffer PMD program in pears has eliminated the need for codling moth sprays, except when the pest flies in from trees that haven’t been cared for. The program monitors PMD effectiveness, using one puffer per acre to account for the lower threshold for damage in pears. Growers can eliminate supplemental codling moth sprays whenever monitoring shows no infestations. Spraying then is necessary only for secondary pests.

The original program was designed to minimize risk to growers by implementing PMD along with a full spray program to reduce codling moth populations. Continuing the full spray program reduced risk to growers, so they were willing to try PMD.

Walnut damaged by codling moth.
Photo by Jack Kelly Clark.

The Situation in Walnuts: Walnut growers were slow to adopt PMD, because there was no way to economically distribute a pheromone in the large canopies of walnut trees.

• 1998: Pear Ester (DA Lure) is developed.
• 1998-2008: Pear Ester tested as lure to monitor effectiveness for mating disruption in walnuts, leading to Combo Lure of codlemone + DA Lure. (D. Light [USDA]; S. Welter and C. Pickel [UC]; UC IPM Walnut Pest Management Alliance)
• 2001: DA Lure is commercially available.
• 2002-2004: Welter shows that, in walnuts, one puffer per two acres is effective, making the program economically feasible for growers.
• 2004-2008: Walnut field demonstration and research using puffers and Combo Lure were initiated. (C. Pickel, J. Grant, S. Welter [UC])
• 2009: IMPACT—puffers are in use in 10,000 acres of walnuts, or 10% of susceptible varieties.

Growers using the puffer PMD program have eliminated codling moth sprays after only two to three years, but they have to be more attentive to walnut husk fly and aphid monitoring, since codling moth sprays helped keep populations of these pests low.

Growers became interested in using the puffer PMD program in walnuts when demonstrations showed the overall cost of the program was the same as a spray program. Growers initially had been concerned about the logistical issues associated with installing puffers in the large canopies of walnut trees, but demonstrations show the additional cost is very low.

Contact

Carolyn Pickel, (530) 822-7515

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