Fruit Canker Disease Management in Guava: Symptoms, Treatment, Cultural, Chemical, and Preventive Measures

Fruit Canker Disease is a common and destructive fungal disease that affects guava plants. The disease is caused by the fungus Pestalotiopsis psidii, which primarily infects the fruits, stems, and leaves of the guava plant.

Fruit Canker Disease Management in Guava:

The Causal Organism of Fruit Canker Disease

The causal organism of Fruit Canker Disease in guava is a fungus known as Pestalotiopsis psidii. This fungus belongs to the family Amphisphaeriaceae and is characterized by its ability to colonize and infect guava fruits, stems, and leaves. The fungus produces small, black fruiting bodies called pycnidia, which contain numerous spores that can be disseminated by wind or water. When the spores come in contact with a susceptible host plant, they germinate and penetrate the plant’s tissue through wounds or natural openings, such as stomata or lenticels.

Once inside the plant, the fungus produces a range of enzymes and toxins that cause necrosis or death of the plant cells. This results in the formation of circular, brown, or rust-colored lesions on the surface of the fruit, which can eventually lead to the fruit’s deformation, mummification, and drop. Under favorable conditions, such as high humidity and temperatures ranging from 15-30°C, the fungus can sporulate and produce new spores, which can be disseminated to healthy plants and start a new infection cycle.

The Disease Cycle of Fruit Canker Disease

Inoculation: The pathogen enters the host plant through wounds or natural openings, such as stomata or lenticels, on the surface of the fruit.
Infection: Once inside the plant, the pathogen colonizes the tissue and causes necrosis or death of the plant cells. This results in circular, brown, or rust-colored lesions on the fruit surface.
Sporulation: As the lesions progress, they may tear open the epidermis of the fruit in a circular manner, forming a crater-like appearance. In advanced stages, white mycelium consisting of numerous spores may be visible.
Dissemination: The spores produced by the pathogen can be disseminated by wind, rain, or contact with infected plant material, thereby spreading the disease to other healthy plants.
Secondary infection: In conducive environmental conditions, such as high humidity and temperatures ranging from 15-30°C, the spores can germinate and infect other healthy plants, starting a new disease cycle.

Causes/Conditions Favorable for Fruit Canker Disease Spread in the Field.

Temperature: The optimal temperature for spore germination and disease development is around 30°C. Temperatures below 15°C or above 40°C are unsuitable for spore germination or disease development.
High humidity: The disease spreads rapidly under high humidity conditions, with relative humidity above 96%.
Rainfall: Rainfall provides moisture for the fungus to grow and spread, leading to an increased incidence of Fruit Canker Disease.

Symptoms of Fruit Canker Disease

Minute, brown, or rust-colored circular necrotic areas on green fruits
The lesions tear open the epidermis of the fruit in a circinate manner.
The margin of the lesion is elevated, and a depressed area is noticeable inside.
The appearance of the lesion is more noticeable on fruits than on leaves, giving the fruit a crater-like appearance.
In older cankers, white mycelium consisting of numerous spores is noticeable.
In severe cases, raised cankerous spots to develop greatly, and the fruits break open to expose seeds.
Infected fruits remain underdeveloped, become hard, malformed, mummified, and drop.
Sometimes, small rusty brown angular spots appear on the leaves.

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Fruit Canker Disease Management in Guava by Cultural method

Summer irrigation: Proper irrigation during the summer can help reduce the incidence of Fruit Canker Disease by maintaining adequate moisture levels and preventing plant stress.
Pruning and thinning: Regular pruning and thinning of guava trees can promote good air circulation and light penetration, reducing the incidence of Fruit Canker Disease.
Plant spacing: Proper spacing between guava trees is essential to promote good air circulation and light penetration, which can reduce the incidence of Fruit Canker Disease.

Fruit Canker Disease Management in Guava by Chemical method

Bordeaux mixture: A 1% mixture can be applied to guava trees through three to four sprayings spaced two weeks apart. This can help prevent and control the spread of Fruit Canker Disease.
Lime-sulfur: A 1 in 25 dilutions of lime-sulfur can be sprayed on guava trees to control Fruit Canker Disease.
Aureofungin: A PH wash with aureofungin at a concentration of 200 ppm can protect fruits from Fruit Canker Disease for up to 5 days.
Aretan: Dip treatment of guava fruits with Aretan can help control fruit rot caused by Fruit Canker Disease.

Fruit Canker Disease Management in Guava by Organic/Natural method

Use of biocontrol agents: The use of biocontrol agents such as Trichoderma viride and Pseudomonas fluorescens are effective against the pathogen Pestalotiopsis psidii. These agents can be applied to the soil or sprayed on the plants.
Use of organic fertilizers: Using organic fertilizers such as compost and vermicompost can help improve soil health and plant immunity. This can make the plants more resistant to diseases.

Preventive Measures for Control of Fruit Canker Disease

Use canker disease-free nursery plants: It is essential to use healthy nursery plants free from the pathogen to avoid introducing the disease into the orchard.
Pruning and burning infected twigs: Infected twigs should be pruned and burned to prevent the spread of the disease to healthy parts of the plant. The pruning should be done during the dormant season, and care should be taken to avoid injuring the plant.
Spraying copper-based bactericides: Copper-based bactericides can control the disease by reducing the number of spores on the surface of the fruit and leaves. The bactericides should be applied before the onset of the disease and at regular intervals to maintain their effectiveness.
Developing canker-resistant varieties: Guava varieties resistant to the pathogen can be an effective long-term strategy for controlling the disease. This can be achieved through breeding or genetic modification of the plant.

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Conclusion

Effective control of Fruit Canker Disease in guava involves understanding the life cycle of the causal organism and implementing strategies to interrupt its spread. This can include good orchard management practices, such as sanitation, pruning, proper irrigation and nutrition, and cultural and chemical control methods.

Fruit Canker Disease Management in Guava: Symptoms, Treatment, Cultural, Chemical, and Preventive Measures

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