A tachinid fly stalks an obliquebanded leafroller larva. Tachinids are an important natural enemy of leafrollers in the Pacific Northwest.

A tachinid fly stalks an obliquebanded leafroller larva. Tachinids are an important natural enemy of leafrollers in the Pacific Northwest.

by Keith Granger & Jay Brunner, WSU

The Washington State University Pest Management Transition Project is offering a series of field days to demonstrate practices in the field that will help tree fruit growers build successful integrated pest management programs.

PMTP is working with Washington apple growers to facilitate the adoption of new pest control technologies as azinphos-methyl (Guthion) is phased out. Though there have been many new pesticides ­registered as alternatives to azinphos-methyl, integrating these new pesticides has brought new challenges. PMTP is working to overcome these challenges through a comprehensive program of education, training, and assessment.

Tree fruit producers, pesticide applicators, and field representatives are invited to come to the field days on May 28 in Prosser, June 3 in Brewster, June 10 in Quincy, or June 11 in Wapato to learn about pest management practices and current pest management research from leaders in tree fruit research and ­extension. Interpretation from English to Spanish will be available.


On a cost-per-acre basis, new pesticides are significantly more expensive than azinphos-methyl. A monitoring plan for pests that utilizes degree-day models, trapping, and visual inspections can improve the efficiency of pesticide use by optimizing application timing and identifying specific areas that need, or do not need, pest controls.

Degree-day models use site-specific temperature data in order to predict insect development, which is important when timing applications of pesticides that are effective against a specific life stage of the pest. A good trapping system measures the density and distribution of the pest population, which can help with decisions about the type of controls necessary and the size of the area that will need to be treated. Visual inspections provide confidence in pest control programs and alert growers to problem areas and hot spots. Tactics and approaches for building a monitoring plan will be a focus of this year’s field days.

Biological control

New pesticides have not all been as "soft" or selective as had initially been hoped. In some cases, replacing organo­phosphate pesticides has destabilized IPM systems that had been in place for decades. The disruptive effects on biological control have resulted in pest outbreaks that had not been anticipated. Enhancing Western Orchard Biological Control is a collaborative project among Washington State University, the USDA-ARS, Oregon State University, and the University of California at Berkeley that is focusing on improving the stability of IPM programs in apple, pear, and walnut orchards by enhancing biological control. Among the objectives of EWOBC are:

• evaluation of the effects of newer pesticides on key natural enemies

• characterizing the seasonal biology of key natural enemies, and

• evaluating methods for monitoring natural enemy presence and abundance over time.

The role of biological control, identification of key natural enemies, and EWOBC progress on developing monitoring tools for key natural enemies will be part of the summer field days.

Sprayer technology

Improving spray deposition within the orchard canopy while reducing drift can save money and provide better pest control. A patternator is a device that can be used to help determine the vertical distribution of sprayer output in comparison to the target canopy. After analyzing spray distribution, growers can adjust the nozzles on their sprayers to maximize deposition in the canopy and minimize under and over tree drift. Because of the directional spin of the fan on an airblast sprayer, the pesticide movement to the right of the sprayer tends to be upwards while on the left side of the sprayer the general air movement is downward. This can result in uneven spray distribution. Mapping output from each side of the sprayer can help growers make the adjustments that are necessary to better direct sprayer output, which will improve distribution of pesticide and lead to better efficacy throughout the orchard. The use of a patternator, built by PMTP and the WSU Tree Fruit Extension team, will be demonstrated at each of the PMTP field days.