Scatter the treasures of cucurbits

Zucchini

The scientific name : Anthracnose of cucurbits
The causative fungus Colletotrichum orbiculare Arx
Symptoms of cucurbit anthrax :
Symptoms of cucurbit anthrax appear on the leaves in the form of small yellow spots, which expand to reach 1-2 cm and become black in color.
The affected tissue dries up, and the dead spots may fall off, leaving holes in their place.
The petioles of the leaves and the petioles of the fruits are affected, which leads to the fruits turning dark, withering and dying.
Severe injury to the stems leads to splitting, drying of the leaves, and death of the plant.
Fruits become susceptible to infection near the time of maturity, as circular spots appear on their surface, watery in texture, dark and sunken, ranging in diameter from 0.5-10 cm, and their depth may reach 8 mm. The spots expand quickly in the field, and during transportation and storage, and can combine with each other in one big smear. The center of the spots takes on a dark or blackish color, and pink spore masses appear on them in humid weather.

A picture shows you the beginning of the injury

An image showing the symptoms of an injury

A picture showing symptoms on fruits

An image showing the symptoms of a leg injury

Causes of dispersal of cucurbit treasures:
The fungus can maintain its life in the absence of the host in the remains of infected plants.
The fungus can be transmitted by seeds.
It is easily spread by rain spray.
The disease develops in warm and humid environmental conditions
It is transmitted by wind, agricultural equipment and overhead irrigation (free water on leaves).
It is transmitted by the spotted and striped cucurbit beetle.
The disease is most prevalent in warm, humid climates.
Suitable conditions for the spread of cucurbit anthrax:
During the humid summer, the disease can be very severe
Humidity 100% for 24 hours (heavy rain, overhead irrigation, or lack of drainage of irrigation water).
The ideal temperature for the fungus to spread is 24°C, and spores do not spread at temperatures less than 4.4°C or more than 30°C.
The anther development cycle of cucurbit treasures:
It is transmitted through seeds and soil and can cause losses when control measures are not practiced. The pathogen lives among crops, in infected crop debris, or in weeds from the Cucurbitaceae family.
It is spread by frequent rain, warm temperatures (74-78 degrees Fahrenheit) and high humidity that help the disease develop.
The fungus does not require a wound for infection to occur
Losses from the spread of cucurbit treasures
Severely infected fruits often become tasteless, or even bitter, and are susceptible to attack by bacteria and fungi that cause soft rot.
Economic losses

A picture showing a severe injury

Control strategy
Preventive measures to prevent the occurrence of the disease
Getting rid of previous crop residues by burning them or deep plowing.
Getting rid of weeds.
When overhead irrigation is necessary, it is preferable to perform it early in the morning to allow the foliage to dry before nightfall.
Good ventilation.
Controlling the cucurbit beetle.
Avoid infection with agricultural equipment.
Chemical and organic control recommendations

Organic control: Cultivation of varieties resistant to common anthracnose strains

-Use healthy seeds from a reliable source that are free of disease. Seeds can also be disinfected with fungal disinfectants.

- Follow an appropriate agricultural cycle

Chemical control: Spraying plants with appropriate fungicides such as chlorothalonil, diphenoconazole, carbendazim, mancozeb, manib, and methyl thiophanate.
Spraying with neem oil, a natural compound, as a preventive measure every 7-14 days. It is multi-functional, kills eggs, larvae and adults and prevents fungal attack.
References
Gardner, M. W. (1918). Anthracnose of cucurbits (No. 727). US Department of Agriculture
Prakash, O., Sohi, H. S., & Sokhi, S. S. (1974). Studies on Anthracnose Disease of Cucurbits Caused By Colletotrichum Lagenarium (Pass.) Ell. &Halst. And Its Control. Indian Journal of Horticulture, 31(3), 278-282
Rhodes, B. B., & Love, S. (1983). Resistance to Anthracnose in Cucurbits-An Overview. Cucurbit Genetics Cooperative, 32

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