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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

Bean leaves with yellowish blotches
Bean leaves with curled edges and bumps
  • Plant resistant varieties.
  • Control weeds in and around the field.

Bacterial leaf diseases

Bean leaves with brown blotches and small holes
Bean leaves with browning and yellowing from common blight
  • 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

White mold on bean leaves
White mold on stem of bean plant
Bean plant with symptoms of 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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Aluminum foil around bean plant stem during transplanting to prevent cutworm infection
Beans stems infected by cutworm
  • 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

Yellow beetle with black spots feeding on a green leaf
Several holes in green leaves
  • 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

Bean leaves with spider mite infestation
Leaf with bumps and yellowish discoloration
  • 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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