Apollo Trial

Project Title

On Farm Research Evaluation of the Miticide, Apollo for Spider Mite and Rust Mite Control and Impact to Predator Mites on Apples.

Start Date and Duration

June thru August, 1997

Investigator/ Collaborators

WSU Nooksack Watershed IPM Project with grower collaborator:

Tom Sewell

Funded by Environmental Protection Agency, Clean Water Act, Section 319 grant; administered by Washington State Department of Ecology.

Project Description/How was it done?

Apollo is a newly registered miticide in apples, which has activity against both egg and mobile spider mite stages. It is registered for early season (pink stage) applications and targets overwintering European Red Mite (ERM) eggs prior to hatch. History in this area has shown that the Gala variety when compared to Jonagold is more likely to develop economic ERM populations. This grower was interested in determining the efficacy of this miticide for controlling ERM as well as its influence on predator mites and rust mites. Apollo was applied to a Gala block at I ounce/1 00 gals. water/acre on April 17 at pink stage as one of several materials in a tank mix that also targeted apple scab and miscellaneous insect pests. An adjacent Jonagold block did not receive any Apollo. Beginning in mid-June, leaves were collected from 2 sites within each block, and returned to the lab for extraction using a mite brushing machine and counted under a microscope. This procedure is described in WSU Extension Bulletin 1246. Samples were taken on five occasions at approximate 2-3 week intervals through late August.

Results

Based on mite populations from the previous season, the Gala block should have had a significant overwintering population or ERM, with the potential to build to economic density during the '97 season. However, ERM although detected in most samples, never increased to any significant level. See the attached tables and graphics for sampling results. The highest count in the Apollo treated area was .13 mites/leaf which is extremely low. ERM egg counts were very low as well. ERM increased to slightly over 4 mites/leaf in the untreated Jonagold block by mid August, but this was well below threshold as well. ERM are usually not a problem on this variety. There was a significant difference in apple rust mite density between the two areas. Populations never exceeded I 00/leaf in the Apollo -treated Galas, but were over 300/leaf in late July and early August samples in the untreated Jonagolds. 300 rust mites/leaf is the traditionally accepted treatment threshold for rust mites in apples. There was no significant difference in predator mite densities between these two treatments. The western predatory mite, Typhlodromus occidentalis as detected in both areas at each sample, eventually building to 2-3 mites/leaf in early August. Although the density was slightly lower in the Apollo-treated plot in August, this difference is not significant and may have been due to lower prey density at that time.

Any problems or limitations?

If this work is repeated, the study should be restricted to a single variety.

What did we learn?

Early season use of Apollo provided excellent season-long control of European Red Mites with no measurable impact on the predatory mite, T. occidentalis. Apple rust mite populations were significantly lower in the Apollo-treated Galas compared to the untreated Jonagolds. The low rust mite population in the Apollo-treated area provided enough prey to support the predatory mite, T. occidentalis, at significant levels.

Where do we go from here?

Discussion and possibly another on-farm trial in Galas only, to help determine how to best use this material. Additional work should start with a pre-treatment survey of fruiting spurs to measure density of overwintering ERM eggs.

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