potato insect damage - Ask Extension
Potatoes have been severely damaged the last two years by what I believe is caused by insects. I am aware that it is not advisable to plant in the sa...
Knowledgebase
potato insect damage #780899
Asked January 27, 2022, 6:50 PM EST
Potatoes have been severely damaged the last two years by what I believe is caused by insects. I am aware that it is not advisable to plant in the same location every year and I do move the planting as much as possible but not able to do this very much or far due to space limitation. The damage penetrates the tuber about one quarter inch or more and I cannot find any worm at that depth although I don't have much magnification capability. This is a home garden and I typically produce about 1000 pounds to give to friends and neighbors. Will attempt to attach image. Thank you
Washington County Oregon
Expert Response
Vernon,
Those shallow pits in the potatoes are likely due to wireworm larvae (the youngsters, often referred to as Leatherjackets). The adults are called Click Beetles. The reason you're not finding the pests is that the larvae damage the crop early to mid-season.
As you already know, pest damage can be limited by rotating the crop from one site to another. The preferred interval in the rotation is 3 to 4 years.
Other important facts about wireworms are these:
- Damage is most common where soil has a high organic content.
- If you use a cover crop in alternate years, avoid red or sweet clover, as well as grasses.
- Dig the crop a reasonably short time after the vines die; the longer the potatoes remain in the ground, the more likely damage will increase.
- Plant fresh, certified potato seed; don't use potatoes from a previous year's crop.
These research-based resources provide lots of info, which should offer you at least a few new insights:
- Wireworms - Good images of the pests, as well as info about Cultural Management in the final paragraph.
- Potato, Irish - Wireworm - More images and background information, plus a section labeled Home Management that includes both Cultural and Chemical Management
- Growing Potatoes in the Willamette Valley offers more information, and suggests an alternative planting method of an above ground, 2-3-foot tall, cylinder made of wire-fencing. Place straw, leaves, or newspaper just inside the wire to retain the soil. Potato Towers contains an image of such a planted tower.
- Grow your own potatoes is the most extensive, fact-filled of these publications, including cultivar selection.
- How to grow potatoes is a rapid review of critical factors.
Those shallow pits in the potatoes are likely due to wireworm larvae (the youngsters, often referred to as Leatherjackets). The adults are called Click Beetles. The reason you're not finding the pests is that the larvae damage the crop early to mid-season.
As you already know, pest damage can be limited by rotating the crop from one site to another. The preferred interval in the rotation is 3 to 4 years.
Other important facts about wireworms are these:
- Damage is most common where soil has a high organic content.
- If you use a cover crop in alternate years, avoid red or sweet clover, as well as grasses.
- Dig the crop a reasonably short time after the vines die; the longer the potatoes remain in the ground, the more likely damage will increase.
- Plant fresh, certified potato seed; don't use potatoes from a previous year's crop.
These research-based resources provide lots of info, which should offer you at least a few new insights:
- Wireworms - Good images of the pests, as well as info about Cultural Management in the final paragraph.
- Potato, Irish - Wireworm - More images and background information, plus a section labeled Home Management that includes both Cultural and Chemical Management
- Growing Potatoes in the Willamette Valley offers more information, and suggests an alternative planting method of an above ground, 2-3-foot tall, cylinder made of wire-fencing. Place straw, leaves, or newspaper just inside the wire to retain the soil. Potato Towers contains an image of such a planted tower.
- Grow your own potatoes is the most extensive, fact-filled of these publications, including cultivar selection.
- How to grow potatoes is a rapid review of critical factors.
