Enhancing biological control in mating disruption pear orchards by understory management

2001 Annual Report for SW99-011

Project Type: Research and Education
Funds awarded in 1999: $110,497.00
Projected End Date: 12/31/2001
Matching Non-Federal Funds: $21,757.00
Grant Recipient: USDA-ARS
Region: Western
State: Washington
Principal Investigator:

Enhancing biological control in mating disruption pear orchards by understory management

Summary

Effects of mowing frequency on biological control in pear orchards was monitored. Reductions in frequency of mowing led to higher densities of natural enemies, parasitoids, and some pests (mites, Lygus) in the ground cover. Parasitism rates of codling moth and pear psylla were not affected by mowing frequency; however, rates were uniformly too low (below 5%) to allow any strong conclusions to be made regarding parasitism.

Objectives/Performance Targets

1. Determine effects of mowing frequency on insect densities in the ground cover, on the orchard floor, in the soil, and on the pear tree in mating disruption orchards, emphasizing effects on biological control organisms.

2. Quantify parasitism rates of codling moth, pear psylla, and leafminer in plots differing in mowing frequency.

3. Present project at annual Field Days, and prepare extension bulletin summarizing results.

Accomplishments/Milestones

We showed that decreased mowing frequency led to higher densities of predators and parasitoids in the ground cover and (for certain taxa) in the pear tree. There was negligible effect of mowing frequency on ground-dwelling insects. Attempts to determine effects of mowing frequency on parasitism rates of codling moth, pear psylla, and leafminer were unsuccessful due to uniformly very low rates (psylla, codling moth) or uniformly very high rates (leafminer) in all plots.

During year 2001, we finished processing and identifying the arthropods from the soil samples. We recovered and identified more than 25,000 arthropods, which we grouped according to feeding guild. Predatory insects, spiders, and centipedes increased in abundance with decreased mowing frequency.

Work remaining to be done: Prepare extension bulletin for distribution to public. Write publications

Impacts and Contributions/Outcomes

We provided field-day demonstrations on-site on 3 dates; all were well-attended by growers. Publicity generated by the project resulted in invitations to the principal investigator to discuss the project at two ground cover workshops. The publicity also resulted in non-technical publications available through the Western Fruit Grower (vol. 120, #6) and the Organic Farming Research Foundation.