April 1, 2002
Vol. 4 No. 2
Codling Moth Mating Disruption Revisited in 2002
Codling moth mating disruption (CMMD) was first commercially available in Washington in 1991. From just a few thousand treated acres in 1992, its use climbed to close to 90,000 acres in the state by 2001. Growers have adopted this new pest control method because it made economic sense. Faced with increasing codling moth (CM) pressure and control costs, they were able to incorporate CMMD into their pest management programs and reduce both pest control costs and codling moth damage.
This past year has seen increasing concern with CM in the Northwest. Reports of high fruit damage are becoming more common. Several factors are contributing to this growing problem:
Due to increasing CM populations and economic issues facing Washington growers the use of CMMD is being called into question by some in the industry. Does it make sense to continue with CMMD use? I think it still does for most Northwest growers, for the same reasons and with the same qualifiers as before.
CMMD is not appropriate for all orchards and growers. CMMD use is a questionable IPM practice in several situations:
When CMMD is used, keep in mind several key considerations that are critical to success:
Hand-applied Dispensers for CMMD
Almost all CMMD in Washington is conducted with the use of one of several commercially available hand-applied dispensers. Sprayable pheromone and "puffers" (mechanical pheromone dispensers) are also now available. They continue to be refined and have been little used commercially to this point. However, these pheromone delivery methods potentially provide some significant advantages; I'll cover their use in a later issue.
Five dispensers were evaluated in 2001 by the WSU-Tree Fruit Research and Extension Center in Wenatchee (TFREC). They were checked for the duration and rate of release of the primary CM pheromone component, codlemone. Dispensers were clipped onto a line that ran through the canopy of an apple orchard at the TFREC. All dispensers are designed by their manufacturer to be applied just once per season in Washington conditions.
|Dispenser||Company||Labeled codlemone load (mg)||Label rate/acre|
|Isomate-C Plus||Pacific Biocontrol||110||400|
|Isomate-C TT||Pacific Biocontrol||230||200|
|NoMate CM||Scentry Biologicals||120||400|
|Checkmate CM XL-1000||Suterra||270||200|
All dispensers were evaluated by two methods:
- Volatile Trapping System (VTS) Method - Dispensers were collected at approximately 30-day intervals and analyzed in the VTS by Phero Tech of British Columbia. Filtered (clean) air of a constant temperature and flow-rate was run over the dispensers and the codlemone emitted from dispensers was trapped on a special column and measured using a gas chromatograph.
- Residual Analysis Method - Dispensers were collected at the same intervals and analyzed by the WSU Food and Environmental Quality Lab in Richland. All of the pheromone in each dispenser was removed and the amount determined, again using a gas chromatograph.
The VTS method provides a relative comparison of the amount of codlemone released per dispenser type of different ages under constant environmental conditions.
|Calculated mg of codlemone released per dispenser over 24 hours|
|Day||Isomate C+||Isomate CTT||NoMate||Checkmate||Disrupt CM|
What the ideal dispenser would do is release an adequate amount of codlemone for the entire season, that is independent of age. After an initial "burst" affect on day-0, most dispensers had a fairly constant rate of pheromone release. However, there was great deal of difference in the amount of pheromone released by each dispenser type. The Isomate-C plus and CTT dispensers had the highest and most consistent release rates. The Checkmate and Disrupt CM dispensers had consistent but very low release rates. Pheromone release from these latter dispensers could have been inhibited by the way they were arranged in the VTS. Three dispensers of each type were placed in the VTS chamber. It is possible, though Phero Tech does not think it was the case, that air flow was impeded over the Checkmate and Disrupt dispensers thus reducing their pheromone release rate. The NoMate dispenser is an unusual case. The dispenser showed a very high initial pheromone release rate and appeared to run out of pheromone later in the season. See the discussion below for a further explanation of this situation.
The residual analysis method determines the amount of codlemone remaining in dispensers of different ages; the difference in the amount remaining in the dispenser at each time period is a measure of the amount released.
|Average amount (mg) of codlemone remaining per dispenser|
|Age of dispenser (days)||Isomate C plus||Isomate CTT||NoMate CM||Checkmate CM||Disrupt CM|
Most dispensers showed a gradual decline in the amount of codlemone remaining over time. Both Isomate dispensers showed a similar pattern in the amount of codlemone remaining, though by design the CTT dispenser lost about twice as much pheromone as the Isomate-C plus dispenser. The pattern of codlemone remaining in the NoMate was similar to that observed from the VTS analysis. Less than 50% remained in the NoMate dispenser after 35 days and by the end of the first codling moth generation (ca. 84 days) little codlemone remained. The Checkmate dispenser lost codlemone throughout both generations but still had nearly 40% remaining after 162 days. The Disrupt dispenser was the least consistent in codlemone loss, especially in the second generation, and had almost 50% remaining at day 162.
Both methods of analysis showed similar results, and residual analysis showed little isomerized pheromone in any of the dispensers suggesting all were protecting the codlemone from internal breakdown. Both methods of analysis appear to provide an adequate means for measuring pheromone release behavior from hand-applied dispensers and this research will continue in 2002
Rick Hilton of the OSU-Southern Oregon Research and Extension Center evaluated these same dispensers in Medford. Using the residual analysis method, he obtained results that closely matched those found in Wenatchee. The Isomate and Checkmate dispensers continued to lose pheromone for 120-150 days, while the NoMate dispenser was essentially out of pheromone by 90 days.
The manufacturer of NoMate (Scentry Biologicals Inc.) is concerned that the dispensers used in these tests were somehow inappropriately exposed to high temperatures prior to their placement in the orchard. This would cause pheromone in the NoMate dispensers to migrate to the surface and therefore be lost at a faster rate than the dispenser's design should permit. While the dispensers used in the Wenatchee and Medford study were current year NoMate dispensers (red) and were removed from a newly opened package it is possible they were exposed to improper storage conditions prior to use. Improper storage could have affected any of the pheromone dispensers in a similar manner pointing out the importance of proper storage for distributors and growers. In 2002 WSU will again evaluate all hand-applied CM pheromone dispensers but will evaluate all dispensers prior to placing them in the field to make sure they meet label standards.