Guava anthracnose

English nameGuava anthracnose

The scientific name: Colletotrichum gliosporioides Colletotrichum gloeosporioides

The type of disease: A fungal disease

family: Glomerellaceae

Symptoms

Anthracnose can affect the leaves, stems and fruits of guava plants. On leaves, they appear as irregular brown or black spots that may coalesce and cause leaf blight or defoliation. On stems, the fungus can cause cankers, death, and stem girdling. On fruits, the disease initially appears as small, dark sunken spots that gradually enlarge and develop pink spore masses in the centre. Infected fruits may wither, mummify and fall prematurely.

Reasons

Guava anthracnose is caused by the fungus Colletotrichum gloeosporioides, which can survive on plant debris and infect a wide range of hosts.

Propagation conditions

Anthracnose prefers warm, humid conditions with temperatures between 68°F and 86°F (20°C and 30°C) and frequent rainfall or overhead irrigation. The fungus produces spores (conidia) that can be spread by wind, rain or water spray.

Disease course

Anthracnose fungi can overwinter as dormant fungi or survival structures (acervuli, appressoria) on infected plant debris or on the bark of guava trees. In the spring, when temperatures and humidity levels are favourable, the fungus produces spores that can start new infections on leaves, stems or fruit. The disease cycle continues throughout the growing season as long as suitable conditions persist.

losses

Severe anthracnose infection can lead to massive leaf drop, fruit rot, and decreased yield. The disease can also weaken plants, making them more vulnerable to other pathogens and environmental stresses.

Control strategy

An integrated approach including cultural practices, pruning and fungicide applications is recommended for guava anthracnose management.

Preventive measures

Remove and destroy infected plant remains, prune and dispose of diseased branches, and ensure good air circulation in the orchard.

Organic/chemical control

For organic control, copper-based fungicides (such as copper hydroxide and copper sulphate) or biological control agents such as Trichoderma spp. can be effective when applied prophylactically. Chemical fungicides containing active ingredients such as azoxystrobin, pyraclostrobin, or difenoconazole may also be used according to label instructions.

References

https://www.vnrnursery.in/anthracnose https://gd.eppo.int/taxon/SPHAPS/photos