Plant Pathology Infobytes

June 29, 1998
Steps for Blight-Free Lima Beans

Lima beans, better known as butter beans to most Southerners, are garden favorites. They make great summer time dining and are easily freezer-processed for winter enjoyment. Unfortunately, growing this crop can sometimes be difficult because of a fungus disease known as anthracnose pod blight.

This disease attacks leaves and stems but most of the damage occurs when pods and the beans inside become infected, turn reddish brown, and often become "moldy."

The most common symptom of anthracnose is a brick-red discoloration on the pod. Pod infection is first seen as small reddish streaks or blotches. These spots enlarge quickly under favorable conditions until the entire pod surface is covered.

How does anthracnose pod blight get started? The first symptoms of the disease show up on young leaves as red blotches. On these diseased areas, the causal fungus produces millions of tiny spores (microscopic seed-like structures) which spread to and infect young pods.

The anthracnose fungus carries over from one season to the next through infected seeds and in crop debris left on the soil surface. It may also overwinter on other host plants (vetch, lespedeza and related leguminous plants).

How do you handle this disease? The following control procedures are suggested.

  • Start each planting season with fresh seed, since the anthracnose fungus carries over in seed.
  • Use fungicide-treated seed.
  • Never plant lima beans on the same land more than once every three years since the causal fungus can survive in soil and trash for at least this period.
  • Do not plant lima beans adjoining fields planted to soybeans, alfalfa, southern peas, or following these crops.
  • Fall-planted lima beans should not be grown in the immediate vicinity of fields where anthracnose was a problem in the spring crop.
  • Fungicide sprays with approved fungicides will reduce the amount of disease.
  • Although a full-season fungicide application program gives better results, application beginning at bloom is critical.
  • Apply a copper containing fungicide according to the rates and directions given for bean crops. Such fungicides are generally available at most garden and farm supply stores under a variety of trade names such as Kocide DF or Kocide 101.


Written by the late Dr. Frank Killebrew

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