Guava
Canker of Guava
Pestalotiopsis psidii
Fungus
In a Nutshell
- Minute, brown, rusty necrotic areas on fruits.
Can also be found in
Guava
Symptoms
The disease generally occurs on green fruits and rarely on leaves. The earliest symptoms of infection on the fruit are the appearance of minute, brown, rusty coloured necrotic areas. In the advanced infection stages, the necrotic areas tear open the epidermis. Infected fruits remain underdeveloped, hard, malformed and drop.
Recommendations
Organic Control
Use foam nets to bag the fruits to prevent fruit injury.
Chemical Control
Always consider an integrated approach with preventive measures together with available biological treatments. Protectant sprays of Bordeaux mixture or copper oxychloride can sufficiently control the disease spread. Protective applications with systemic insecticides to young fruits after pollination have reportedly shown positive results.
What caused it?
The disease is caused by the fungus and the primary source of inoculum is a dormant mycelium. A quick attack of the fungus causes fruit damage. The infection can be spread secondarily by wind-borne conidia, water splash, proximity to infected plants, injury, and transportation of infected leaves. The fungus can grow in humid environments at temperatures between 20 and 25°C with a dense canopy and insufficient airflow.
Preventive Measures
- Practice summer irrigation and nutritional management to reduce the disease.
- Bag fruits when they are bear sized using foam nets to prevent injury to the fruit.
- The pathogen is primarily a wound parasite.
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