Friday, September 11, 2009
Potato leaves roll upward for several reasons, not necessarily because of virus leafroll.
Varietal response to environmental factors—especially inadequate nutrition or intense light and long days—causes relatively uniform leafrolling throughout a field or a portion of it, in both symptom severity and time of onset.
Leafroll may also be due to genetic factors influencing the response of certain clones, and can cause variability in potato populations grown from true seed.
Rolling caused by improper plant nutrition is not fully understood. Mineral deficiencies involving minor elements and nitrogen toxicity are important.
Aphid populations on the plant can cause toproll in the absence of the leafroll virus.
Nonvirus leafroll is not infectious and leafrolled plants usually yield well.
Proper diagnosis of leafrolling is particularly important in potatoes seed programs.
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