Anthraclose

Disease name: anthraclose

Scientific name: Colletotrichum

Type of disease: bacterial pathogen

Disease family: Colletotrichum acutatum

• The causes of disease:

The fungus Colletotrichum acutatum is the cause of anthraclosis, as it infects leaves, fruits, and branches if the appropriate humidity and temperature are available. The fungus needs a hot climate with continuous humidity for 12 hours to spread and infect green plant parts. Even if the climatic conditions are not suitable, it enters Mushrooms are in a dormant stage until weather conditions become suitable.

Symptoms of the disease:

The fungus causes small necrotic spots on the leaves that may develop to form a hole in the leaf, as the presence of purple color on the edges of the leaf indicates the advanced age of the infection. The death of branches and premature leaf fall are the most important symptoms of anthracnose infection, as dead leaves and branches become covered with dark fungal spores.

• Conditions suitable for the spread of the disease:

The disease is most common during the spring season with long periods of humidity, especially when there is heavy rain and the temperature ranges between (20-30°C) and the presence of a high percentage of dew.

• Disease development cycle:

The fungus takes the form of mycelium in the winter, where it is found on dead wood in trees, on infected branches, and fallen plant remains on the soil and inside the soil. When suitable climatic conditions are available, the fungus begins to develop and form spores, as the asexual spores spread over short distances due to water droplets that stain the plants. As for the native wag, it can spread over long distances due to the wind.

• Losses from the spread of disease:

If preventive and curative steps are not taken in the early stages, the disease will spread from the leaves to the branches and fruits, which will increase the material losses of the crop, as the spores present on the fruits and branches develop, which negatively affects the commercial value of lemons after harvesting and during storage.

• Control:

1. Spraying neem oil helps in controlling the infection.
2. Organic copper spraying helps control the disease in its early stages.
3. The use of fungicides containing azoxystrobin or chlorothalonil reduces the risk of spreading the infection.
4. Take into account the time of spraying, which is early in the morning, and the correct method of spraying on the leaves.

• Preventive measures:

1. Treat the seeds before planting by immersing them in warm water to kill the fungi.
2. Choose fungi-resistant seeds.
3. Providing the field with a good water drainage system.
4. Good care for the field by removing harmful plants and dead plant remains, as they are a good source of germs, and cleaning agricultural tools well before use and sterilizing them if they are used in an infected field.
5. It is recommended to use drip irrigation.

• Sources:
• https://ipm.ucanr.edu/agriculture/citrus/anthracnose/
• https://plantix.net/en/library/plant-diseases/100122/anthracnose-of-citrus/