The Q&A Archives: Potato leaves turn rust color and die

Question: Every year the leaves on my potato plants turn rust colored and die, eventually killing the whole plant by the end of July. What's the problem? Linda Hoffman Union, IL

Answer: The symptoms sound like verticillium wilt, say Darin Eastburn, plant pathologist at the University of Illinois in Urbana. This soil borne fungus infects developing potato roots, clogging the vascular tissue. The final signs of the disease, which somecall potato early dying, are the yellowing of leaves, says Eastburn. The disease is often introduced to gardens from soil on seed potatoes. Even certified seed potatoes may contain low levels of this disease, says Eastburn. Once in the soil, the disease can last for many years on a wide range of host plants, including sunflowers, asters and cabbage, he explains. The most practical solution is to plant moderately resistant potato varieties, such as Red Pontiac, Nooksack and White Rose, says Eastburn. You can also lessen the severity of the disease by lowering the pH to 6.0, where the disease is less active, he adds.

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