Anthracnose Disease on Beans Production: Identification & Control

May 9, 2023November 16, 2023 Agric4Profits

Anthracnose can reduce yield and quality. The pathogen that causes this disease survives in seeds and plant residues, and an epidemic can begin from either source. Infections occurring early in the growing season usually result in greater yield and quality losses.

As such, infections occurring from infected seeds are particularly devastating. Anthracnose can develop at any time during the growing season if cool, wet weather occurs.

Anthracnose symptoms initially are observed as linear, dark lesions on the veins on the underside of leaves. These lesions eventually can be seen on the upper side of the leaves and petioles and stems. Symptoms may mimic other biotic or abiotic ailments, so accurate identification is important.

Infection on pods produces reddish-brown circular cankers 1/8 inch or greater in diameter. Larger areas of pods can be destroyed when these cankers merge. Under moist conditions, the center of these cankers is filled with beige to pink masses of spores.

Anthracnose symptoms on pods are similar to those produced by bacterial blights. Symptoms on infected seeds can range from slight discoloration to the presence of cankers similar to those produced on the pods.

Importantly, symptomless infections also can occur. This is particularly important in seeds because healthy-looking seeds actually may be infected with the anthracnose pathogen. Planting infected yet symptomless seeds may initiate an epidemic during the growing season.

Once the infection begins, the spores of the pathogen can be moved easily in the field by splashing water and machinery. Long-range spread occurs through infected seeds, infected plant material blowing in the wind, equipment carrying the sticky spore masses, and wind-driven rain.

Anthracnose Disease Management

Clean seed: The most effective way to manage the disease is to prevent its introduction in your fields by planting certified disease-free seed. The use of bin-run seed greatly increases the anthracnose risk.

Seed treatments: Some fungicide seed treatments reduce seed-to-seedling transmission of the anthracnose pathogen, but none provides complete control and none eradicates the anthracnose pathogen in seed because the embryo or inner cotyledon may be infected.

Cultural methods: If you have an infected field, work infected fields last, and wash your implements thoroughly before entering other fields. Avoid cultivating when the canopy is still wet.

Crop rotation: A minimum of a three-year crop rotation is recommended if anthracnose is identified.

Resistance: Cultivars with resistance to anthracnose may be available. Consult the most current information on cultivars.

Scout: Monitor fields for the presence of anthracnose and do not plant saved seed from anthracnose-infected fields.

Foliar fungicides: When applied preventatively at flower initiation and again 10 to 14 days later, foliar fungicides can reduce the incidence of diseased pods and reduce anthracnose-related seed quality losses, but none provides complete control. Consult the most current information on fungicides for the management of anthracnose.