Photo by Jeff Miller

Recognized as a key component in a complex of pests causing potato early die (PED), Verticillium wilt is caused by 2 soil-borne fungi, V. dahlia and V. albo-atrum. According to the University of Maine, at least 140 species of plants are susceptible to Verticillium, including weeds common to potato fields like nightshade, lambsquarters and pigweed, and the fungi have been reported to remain in the soil for up to 7 years without a host crop. In fields with severe PED, losses have been reported as high as 50%.

Symptoms:

• Sometimes indistinguishable from normal plant senescence, early PED foliar symptoms may be limited to uneven chlorosis of older leaves on plants throughout the field.
• Other symptoms include wilting leaflets, yellowing of leaves and chlorosis progressing upwards, leaving erect stems. Inspecting the cross section of the stem base often reveals a light brown vascular discoloration (although this discoloration is not unique to PED).
• Advanced symptoms may include individual declining plants or the apparent early maturation of the entire crop occurring as the season progresses. Verticillium symptoms are highly variable and may be associated with other diseases or physiological problems.

Management strategies:

• Use of resistant potato varieties
• Fertility and irrigation management – optimum phosphorus and potassium soil concentrations and avoiding water stress after flowering
• Crop rotation – green manure crops
• Fumigation

The application of Elatus® fungicide in-furrow at planting for the control of Rhizoctonia, black dot and silver scurf has been shown to suppress Verticillium levels.* Use as a management tool in combination with the strategies listed above for best results.

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*Elatus fungicide has a Section 2(ee) Recommendation for suppression of Verticillium wilt on potatoes in AL, AR, AZ, CO, CT, DE, FL, GA, IA, ID, IL, IN, KS, KY, LA, MA. MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, OH, OK, PA, RI, SC, SD, TN, UT, VA, VT, WA, WI, WV and WY