Alberta potato growers told to look for resistant varieties and take measures to avoid fungicide resistance
RED DEER — Fusarium infections in potatoes are common, but more strains are showing resistance to fungicides.
“Resistance management is an important piece to consider when making plans about how we are going to manage fusarium,” Mike Harding, a plant pathologist at Alberta Agriculture’s Crop Development Centre, told Potato Growers of Alberta’s annual meeting held in Red Deer Nov. 18-19.
“Fusarium is well adapted to survive in Alberta. It is not going away and it has been here longer than we have.”
There is no single way to control the disease, so growers need to use as many best management practices as they can to keep it from destroying an entire crop.
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“Fusarium diseases can sneak up or sometimes cause losses that go seemingly unnoticed,” he said.
“They are especially problematic when we try to store potatoes for a long time because people like to eat potatoes all year long.”
Fusarium can cause dry rot, foliar wilt and decay. It is common in potato fields and can attack a plants’ roots and crown, colonize vascular areas and cause tuber rot.
“We don’t have dry rot every year, but when we do it is a big hit,” he said.
A national fusarium survey started in 2010 has found different types across the country, including fusarium sambucinum, fusarium coeruleum and oxysporum.
“It is important to understand the biology so that we can make the correct decisions,” he said.
- A product such as thiabendazole should control oxysporum, but it may not work on other species of fusarium.
- Fludioxonil is a contact fungicide and more resistance is showing up in the fusarium species that have been surveyed.
- Difenoconazole can still handle F. sambucinum, but resistance issues are expected to appear.
“We need to think carefully about resistance management so we don’t lose the products we have available to us,” he said.
Growers who look for potato varieties that carry resistance need to match the disease to the variety.
Other management controls include:
- Avoid planting in fields infested with fusarium.
- Use clean seed.
- Store in a disinfected facility.
- Remove diseased tubers before cutting.
- Promote rapid wound healing. The potato skin is an effective protector against fusarium, so try and reduce tuber injury during harvest and handling operations.
- Monitor storage conditions.
- Use a registered fungicide seed treatment.
- Don’t use fungicides with the same active ingredients multiple times. Check products’ mode of action so they can be rotated.
- Plant when soil and temperature conditions promote rapid sprout growth and emergence.
