Anthracnose of Soybean

  • Symptoms

  • Trigger

  • Biological Control

  • Chemical Control

  • Preventive Measures

Anthracnose of Soybean

Colletotrichum truncatum

Fungus


In a Nutshell

  • Brown irregular spots on pods and stems.
  • Brown veins and curled leaves.
  • Pods with moldy sterile seeds.
  • Damping-off of infested seedlings.

Hosts:

Soybean

Symptoms

Anthracnose can infect stems, pods, and leaves of the soybean, often without symptoms. Symptoms may become visible only during the reproductive growth stages. When weather conditions become warm and moist, small dark irregular spots appear on stem and pods. These spots may themselves be covered by small black dots. Leaves might curl and veins turn brown. In severely infected pods small, moldy sterile seeds are produced. Early infection of seedlings can lead to damping-off.

Trigger

The pathogen can survive for over a year on plant material. Spores produced on infested residues are blown by wind and rain onto upper leaves. Infection typically occurs when leaf wetness, rain or dew periods exceed 12 h per day.Overall, the disease may have little effect on the yield, but stands and seed quality can be reduced. In regions with favourable conditions (wet soils, warm and humid weather), yield losses can be high.

Biological Control

No biological treatment is available against Anthracnose so far.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatment if available. If more than 5 % of the seeds are infected, a treatment with fungicides is recommended. Chlorothalonil, mancozeb, copper sprays or propiconazole and the systemic fungicide thiophanate-methyl can be used.

Preventive Measures

Plant high quality certified seeds.,Consult with retailer if tolerant varieties are available.,Rotate with nonhost crops to avoid pathogen build-up.,Do not use row distances smaller than 50cm.,Monitor plants regularly and clean tools and equipments.,Store seeds at ambient temperature.,Plow and bury plant residues or simply burn them.