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University of Minnesota Extension

Bean diseases and other pests

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Viral diseases

  • Plant resistant varieties.
  • Control weeds in and around the field.

Bacterial leaf diseases

  • Plant disease resistant varieties.
  • Use drip irrigation.
  • Do not work in plants when wet.
  • After harvest, bury plants.
  • Do not save seeds from infected plants.
  • Do not use plant beans in the same field for 2 years.

White mold

  • Use drip irrigation.
  • Use wide space between plants.
  • Choose varieties with an open, upright growth form.
  • Stake vining varieties.
  • Remove infected plants.
  • Do not compost infected plants.
  • At harvest, discard any beans with soft discolored spots.
White mold on stem of bean plant
White mold on stem; H. Schwartz, CSU, Bugwood.org
White mold on bean leaves
White mold on leaves; H. Schwartz, CSU, Bugwood.org


  • Remove weeds and plant residue.
  • Till garden before planting.
  • Place cardboard collars or aluminum foil around plant stems when planting transplants.

More information on cutworms.

Tilling soil to reveal cutworm infestation on bean plant
Tilling that revealed a cutworm; Clemson Univ. - USDA Coop. Extension slide series

Bean leaf beetles

  • Delay planting beans until mid to late June.
  • Handpick beetles on the beans and place in a pail of soapy water.

More information on bean leaf beetles.

Bean leaf beetle on bean leaf
Bean leaf beetle
Bean leaves with holes from bean leaf beetle infestation
Holes in leaves from bean leaf beetle

Spider mites

  • Keep beans properly watered.
  • Use a water hose to spray a hard stream of water on infested leaves.

More information on spider mites.

Michelle Grabowski, Extension educator and Jeff Hahn, Extension entomologist

Reviewed in 2018

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