Potato psyllids are important pests because they can spread the bacterium that causes zebra chip disease. The only way to manage this disease is to control potato psyllids. We cannot stop psyllids from migrating into potato fields, but we can control them once they have landed. The following strategies are used by potato growers to control potato psyllids using insecticides in the Columbia Basin.
The photo shows a potato psyllid adult and several nymphs (photo by Andy Jensen, NW Potato Consortium).
1) "NO GAPS" PROGRAM WITH EARLY SYSTEMIC INSECTICIDES: Risk-averse growers may choose to use a "no gaps" strategy to control potato psyllids starting with a systemic neonicotinoid insecticide applied at planting or at hilling. This can provide about 60-80 days of residual control. The residual control period will vary depending on the rate of canopy growth, application timing, and the insecticide and application rate. After that, growers can shift to a foliar insecticide program (see below). Early systemic neonicotinoids also control other pests like Colorado potato beetles, beet leafhoppers, and aphids that can show up in potato fields in the early part of the season.
2) "NO GAPS" FOLIAR INSECTICIDE PROGRAM: If an early systemic insecticide product was not used at planting, then risk-averse growers can start a foliar insecticide program when potato psyllids are first detected entering the field, or are known to be migrating into the area. First appearance of psyllids can vary from late May to early July or later in the Columbia Basin. Follow-up applications are made to ensure the plants are always protected as long as psyllids are present or up to two weeks prior to vine kill.
3) RESCUE TREATMENTS: If adult psyllids are not controlled as they enter the field, and eggs and nymphs are present, then insecticides can be applied to control psyllids before they become the next generation of adults. The aim is to prevent colony establishment and exponential population growth. Insecticides that specifically target the egg and nymph stages are generally used in this case. Growers who are not as averse to risk may decide to use this more "reactive" but riskier approach to potato psyllid and zebra chip management.