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Potato Early Dying Assay

Potato Early Dying Disease is a vascular wilt produced by the fungus Verticillium working alone or in conjunction with the root lesion nematode.  It is characterized by premature senescence with a yellowing and wilting of the foliage.
Potato Early Dying Assay (PED)
Our approach is to sample the rotation crop in the season prior to planting potatoes.  We measure verticillium propagules per gram of soil (VPPG), root lesion nematodes per 100cc of soil and per gram of dried root.
Risk Assessment and Economic Threshold:

Risk can be assessed from low to high depending on the soil type, growing area, and variety which account for much of the yield potential in any field.

Low Risk Potential:  Short season varieties, short or cool growing season (<120 days), heavier textured, high organic matter soils.
High Risk Potential:  Long season varieties, long or hot growing    season (>140 days), lighter textured, low organic soils.
Moderate Risk Potential:  involves some combination of the factors listed between low and high potential.  Crop husbandry decisions made during the growing season can greatly tip the scale towards higher risk.

The Thresholds for making fumigation or other management decisions follow:

  • Verticillium levels above 10 VPPG in the absence of nematodes 
  • Verticillium levels above 6 VPPG in conjunction with either moderate soil nematodes (>150/100cc soil) or root nematodes (>2500/gram of dried root).
  • Verticillium levels above 4 VPPG in conjunction with either high soil nematodes (>300/100cc soil) or root nematodes (>5000/gram of dried root).
Management Options:
Fumigation represents the main tool for management of PED, however, nematicides, resistant varieties, green manure crops, and cultural practices such as aggressive fertility, optimum irrigation, planting depth/spacing, and hilling practices all affect the degree of disease expression.  Management of factors leading to plant stress should be a goal for minimizing PED.


Potato Association of America (Sustaining)
American Phytopathological Society (Sustaining)
Society of Nematology (Sustaining)

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