Bacterial and fungal diseases of garlic

Garlic can be prone to bacterial and fungal diseases, and it's important that farmers are proactive in preventing infection and practise appropriate management. Magda du Toit reports.

- Magda du Toit

Growing garlic from seed to harvest requires careful planning, as well as proper and ongoing production management practices to ensure a healthy crop. By paying attention to factors like soil health, watering, and pest and disease management, the risks associated with garlic production can be minimised.

Speaking at the South African Garlic Growers’ Association’s annual conference in Pretoria recently, Elsie Cruywagen, specialist researcher in mycology and plant pathology at the Agricultural Research Council Vegetable, Industrial and Medicinal Plant (ARC-VIMP) Institute, pointed out that garlic is susceptible to several diseases. “Garlic is prone to mainly fungal and viral and to a lesser extent bacterial diseases,” she said.

She added that most of the major fungal diseases are soilborne.

Cruywagen said that although there aren’t any active research projects on at present, ad hoc samples are being received at the ARCVIMP Diagnostic Centre at Roodeplaat.

“In the past we received samples for diagnosis of black mould, blue mould and Fusarium basal rot.”

Cruywagen pointed out that there are about 10 groups of bacterial diseases that affect garlic and over 35 fungal diseases can impair garlic production. Some of these are listed below.

LEAF DISEASES Leaf blight

Leaf blight is caused by Stemphylium vesicarium. The pathogen’s spores are dispersed by wind and are present throughout the garlic growing season, with spore counts increasing as the season progresses. Stemphylium leaf blight thrives in warm and humid climates.

Lesions generally develop during warm temperatures with adequate rainfall or irrigation until harvest. S. vesicarium is also found in onions and asparagus.