- Colletotrichum lindemuthianum
- This fungus can also infect fababean
Why Does it Matter?
- Yield loss. Depending on weather conditions, yield loss from anthracnose can be extremely high.
- Grade loss. Infected seed is likely to be shriveled and discolored and will substantially reduce the seed grade.
What are the Symptoms?
- Infected seed may have dark brown spots and will produce seedlings with small dark lesions on the cotyledons and/or rust-colored specks on the hypocotyls.
- On established plants, look for darkened, collapsed veins on the underside of leaves (disease onset) and angular brick red to purple lesions that soon turn dark-brown to black.
- On pods, look for small tan to rust lesions which enlarge and become dark, sunken areas surrounded by a raised black ring.
- Look for small, black spore-producing structures in the lesions, which produce a salmon-colored ooze.
What is the Disease Cycle?
- Emerging plants generally become infected from spores growing on debris in the soil.
- Symptoms become visible 7 to 8 days after infection.
- Infection starts on the lower parts of the plant and is spread to upper parts by rain splash.
- The disease is favored by warm (20o C to 24o C) weather and infection will only take place if the leaves remain wet for 18 to 24 hours.
- High winds during combining can easily carry infected debris from field to field.
How is it Controlled?
- Plant disease-free seed and use a seed treatment.
- Crop rotation of 3 to 4 years is recommended.
- Seed should not be planted near fields where beans were previously grown.
- Do not bury stubble. Unlike many other fungi, anthracnose decomposes quicker when left on the soil surface.
How Does 20/20 Seed Labs Inc. Test for Anthracnose?
- 200 seeds are surface sterilized to remove contaminants from the seed coat, then placed on culture agar and incubated for 7 days.
- A qualified staff member examines the plates for the presence of Colletotrichum lindemuthianum. Colonies of this fungus are recognizable by the type and color of the mycelium and the spore-bearing structures they produce.
- This test tells you the percentage of infected seeds to 0.5%.
- If a lower percentage is required this can be accomplished by plating more seed (400 seeds will indicate the presence of disease as low as 0.25%).
- This test takes one week to complete.
Please contact us for more information.