Jun 18, 2016Potato pest alert: tuberworms
Potato tuberworm moths were found in traps at 42 percent of the fields monitored by Washington State University. The maps below compare potato tuberworm population densities (based on trapping data) this week and last week.
If you are planning to harvest an early crop in the next 4 to 8 weeks, then you may want to take action, especially if you are in the Lower Columbia Basin. Monitoring the pest will help you decide whether control measures are needed. We use delta traps with a sticky liner and a pheromone lure to monitor potato tuberworm. The lure attracts male potato tuberworm moths. Visit the Northwest Potato Research website to learn more about pheromone traps for monitoring this pest. Tuberworm populations can vary a lot from field to field, so we recommend potato growers deploy traps at each of their fields. The moths are easier to monitor than potato tuberworm larva, but it is the larva that do most of the damage.
Insecticide applications beginning 4-8 weeks before harvest have been shown to reduce damage to tubers. It is very important to consider the pre-harvest interval (PHI) when selecting a product to apply. Cultural practices that reduce tuberworm damage can be very effective. They include 1) eliminate cull piles and volunteers; 2) minimize the time between vine kill and harvest or harvest under green vines (since PTW seed to prefer vines to tubers); 3) maintain soil moisture after vine kill to prevent soil cracking; and 4) maintain more than 2″ of soil over tubers.
Source: Washington State University