Colletotrichum truncatum It is widely known as the causal agent of anthracnose in several crops, especially soybeans.
In some regions, it is also referred to as "black spot" due to the characteristic lesions it causes.
Crops attacked
This fungus mainly affects crops of great economic importance, such as soybeans, beans, cotton, among others. Soybeans, however, are one of the most affected, with significant losses in productivity in years favorable to the development of the pathogen.
Symptoms
Typical symptoms include black spots on leaf veins, stems and pods.
In more advanced stages, infected pods are dark brown to black in color and may become twisted.
Infected seeds often show deterioration, while seedlings may die soon after emergence due to necrosis of the cotyledons.
In severe conditions, there is pod drop or leaf retention on the plant, with a direct impact on productivity.
Etiology and characteristics
Colletotrichum truncatum belongs to the genus Colletotrichum, which groups widely distributed phytopathogenic fungi. It survives in infected seeds and crop residues, being spread by rain, wind and agricultural activities. Infection usually occurs in conditions of high humidity and high temperatures. The pathogen forms fruiting structures called acervuli, visible as small black dots in the infected areas.
Some points:
- Host and survival: The fungus survives mainly on infected seeds and crop residues, which makes it highly persistent in agricultural areas where crop rotation is not adequate.
- Dissemination: dissemination occurs mainly through contaminated seeds, but factors such as wind, rain splashes and agricultural tools contribute to spreading the fungal spores, expanding the area of infection.
- Temperature: the fungus grows best in warm climates, with high temperatures during the crop cycle.
- Humidity: high humidity levels or frequent rainfall are essential for spore germination and infection of host plants.
- Prone regions: regions such as the Cerrado, which combine high temperatures and significant precipitation, favor the fungus.
- Onset of infection: The cycle begins with the germination of spores on plant surfaces under conditions of high humidity.
- Entry into the plant: the fungus penetrates the plant tissues, causing necrosis and spots that evolve into larger lesions and deformations in the pods and leaves.
- Fruiting: during the cycle, it forms structures called acervuli, responsible for the production of spores, which are released and restart the infection cycle.
- Resistance: the fungus can survive for long periods in seeds and crop residues, which makes it difficult to eradicate without effective management practices.
Control
Management of anthracnose caused by Colletotrichum truncatum requires an integrated approach:
- Use of healthy seeds: It is essential to use seeds with proven sanitary quality.
- Seed treatment: has demonstrated effectiveness in controlling the pathogen.
- Crop rotation: rotating non-host crops reduces the survival of the fungus in the soil.
- Soil management: correct fertilization, especially with potassium, can reduce the incidence.
- Application of fungicides in the field: in high pressure situations, the application of fungicides during the crop cycle is recommended
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