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Web blotch Photo Identification

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  • Pest Type: Disease
  • Crops Affected: Peanuts
  • Scientific Name: Phoma arachidicola
Symptoms
Symptoms usually observed are irregular brown blotches of the leaflets. Severe defoliation can occur, particularly if leaflets are also infected with late leafspot. As lesions mature, they become darker with dull, rough surfaces and may completely cover the upper surface of the leaf.

Disease Cycle
The period of time from infection to the appearance of symptoms can be as short as one week. Usually, irregular brown blotches appear on the leaflets. However, symptoms can vary according to weather conditions. When above the optimum disease development temperature of 68 F, a webbed or netlike, tan to bronze pattern may show up. The disease is usually found in cultivars that have little or no resistance to it. Although not a serious problem in the U.S. at this time, web blotch should be considered a potential disease problem as new cultivars with unknown resistance become available.



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