Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Peppermint (Mentha spp.) -- Leaf Blight
 
Cause: A fungus, Cephalosporium sp. It infects leaves through wounds such as those from rust pustules, insects, or machinery.
Symptoms: Irregularly shaped black spots on leaves rapidly coa-lesce and kill them. Infection may move down the leaf petiole into the stem. It develops rapidly in cool, wet weather and causes severe leaf drop, especially if hot, dry weather follows cool, wet weather.
Cultural control:

  1. Minimize mechanical wounds to the crop.
  2. Control insects when at or above threshold levels. See the PNW Insect Control Handbook for details.
  3. Control rust (see Peppermint and SpearmintRust).
Content edited by: Cynthia M. Ocamb on January 1, 2009
 
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