Thursday, July 18, 2024

Bacterial Blights Disease on Beans Production: Identification & Control

Multiple bacterial blights diseases occur in North Dakota and Minnesota: common blight, halo blight, bacterial brown spot and bacterial wilt. Common blight is the most prevalent of the bacterial blights, but others can be severe periodically. Bacterial blights cause leaf and pod lesions, defoliation and shrunken, discolored seed.

All pathogens are seed-borne and can survive on bean residue. The pathogens causing common blight, halo blight, and bacterial brown spots are favored by wet weather and are spread by splashing rain.

An epidemic of these diseases may occur when weather events (for example, hail or high winds) cause small wounds in the leaves, which allow the bacteria to enter the leaf.

Bacterial wilt can begin from seed-borne infection or through wounds in stems or leaves. Secondary infection occurs similarly to other bacterial pathogens.

Bacteria wilt spreads quickly within a plant, and during periods of high temperature and moisture stress, will cause the plant to wilt and eventually die in severe infections.

Common blight lesions on leaves begin as small, greasy green spots, which later develop into large brown areas surrounded by a narrow lemon-yellow border.

Veins near the lesions are darkened. Infected pods develop greasy green lesions with brick red margins. Pod lesions exude yellow ooze in wet weather. Seeds may be shriveled and discolored.

Halo blight first appears as small water-soaked or greasy green spots, which develop into small dead spots. Nearby veins may be darkened. During cool weather, the lesions are surrounded by light green halos up to ½ inch or more in diameter.

Pod lesions are similar to those of common blight except that they exude a creamy white ooze in wet weather. Occasionally, halo blight infections may become systemic, causing stunted, yellow, and malformed leaves. Whole plants also may be stunted.

Brown spot first appears as small water-soaked spots. These spots remain small, turn reddish-brown, and are surrounded by a narrow, light green halo. Nearby veins may be darkened. Pod lesions are similar to those produced by halo blight.

Bacterial wilt often causes the whole planting to wilt, particularly under hot and dry conditions. Foliar symptoms include interveinal necrotic lesions, sometimes with yellow borders, similar to those of common blight. If the plant survives long enough to produce seed, the seed often is stained in different colors (commonly yellow, purple, or orange).

Read Also: Six (6) Dry Beans Principles of Disease Management

Bacterial Blights Disease Management

Clean seed: Plant high-quality certified seed.

Crop rotation: Use a three- to four-year crop rotation.

Resistance: Breeders and pathologists actively work to develop dry edible beans that are less susceptible to bacterial blights. Consult the most current information on cultivars to help manage bacterial blights.

Fungicides: Fungicides do not work on bacteria. Cupric hydroxide (copper) compounds have been used in a program approach (multiple applications) in the central Great Plains under irrigated conditions and have shown good results in that environment.

These products often have to be applied multiple times for disease management. North Dakota trial results have been inconsistent and additional research is being conducted.

Additional products, such as hydrogen peroxide sanitizers, have shown similar efficacy in some studies.

Read Also: Watershed Pollution Solutions and Management


Benadine Nonye is an agricultural consultant and a writer with several years of professional experience in the agriculture industry. - National Diploma in Agricultural Technology - Bachelor's Degree in Agricultural Science - Master's Degree in Science Education - PhD Student in Agricultural Economics and Environmental Policy... Visit My Websites On: 1. - Your Comprehensive Practical Agricultural Knowledge and Farmer’s Guide Website! 2. - For Effective Environmental Management through Proper Waste Management and Recycling Practices! Join Me On: Twitter: @benadinenonye - Instagram: benadinenonye - LinkedIn: benadinenonye - YouTube: Agric4Profits TV and WealthInWastes TV - Pinterest: BenadineNonye4u - Facebook: BenadineNonye

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