1a. Objectives (from AD-416)
Develop integrated pest management for insects vectoring diseases in Pacific Northwest potato crops.
1b. Approach (from AD-416)
Determine susceptibility of different potato plant growth stages to BLTVA phytoplasma under field conditions using leafhopper exclusion and exposure studies. Determine susceptibility of different potato plant growth stages to BLTVA phytoplasma under field conditions by timing applications of selected insecticides targeted against the beet leafhopper. Assess the impact of the timing of BLTVA infection on the potato yield, tuber processing quality, and phytoplasma transmission rate in daughter tubers. Develop treatment (action) thresholds for the beet leafhopper to reduce incidence of purple top disease in Columbia Basin potatoes.
3. Progress Report
The project goal is to develop management strategies for beet leafhopper and potato purple top disease. The project addresses NP 304 2A, Protection of Agricultural and Horticultural Crops, Biology and Ecology of Pests and Natural Enemies, and 2B, Protection of Agricultural and Horticultural Crops Control. Several insects, including aphids and beet leafhopper, are serious pests of potato in the Pacific Northwest. The objective of this research project is to develop integrated pest management program for potato insect pests in the Pacific Northwest. For the second year, experiments were conducted on the pathogen BLTVA phytoplasma that causes potato purple top disease and the beet leafhopper, its insect vector. These experiments 1) determined potato plant growth stages susceptibility to BLTVA phytoplasma infection and the relationship between beet leafhopper density and purple top development; 2) determined timing of insecticide sprays targeted against the beet leafhopper; 3) assessed the impact of the timing of BLTVA infection on the potato yield, tuber processing quality, and phytoplasma transmission rate in daughter tubers; and 4) determined treatment thresholds for the beet leafhopper to better manage purple top disease in Pacific Northwest potatoes. It was determined that younger plant growth stages of potato are more vulnerable to BLTVA phytoplasma. Also, it was confirmed that as few as one BLTVA-infective beet leafhopper per potato plant is enough to cause purple top disease and significant yield loss. Information from these studies will help growers in developing treatment thresholds to better manage beet leafhopper and reduce incidence of purple top disease, in addition to reducing insecticide use in Columbia Basin potatoes. This project addresses objective 3 of the related in-house project. Monitoring of activities and progress on this project was accomplished by direct supervision of on-site employees, and use of site visits, e-mail and telephone to communicate with off-site collaborators.