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University of Minnesota Extension

Quick guide to insects and diseases of beans

Quick facts

  • This page highlights non-chemical practices to prevent or manage common insect and disease problems of beans. 
  • For more detailed information follow the links in each section.
  • Click on an image to enlarge it.
  • See Growing healthy vegetables for more detailed information on how to keep your garden disease and pest free.

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.

More information on bacterial brown spot.

White mold

  • Use drip irrigation.
  • Leave wide spaces between plants.
  • Choose varieties with an open, upright growth form.
  • Stake vining varieties.
  • Remove infected plants.
  • Do not compost infected plants.
  • At harvest, throw away any beans with soft, discolored spots.

More information on white mold.

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  • 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.

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.

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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