Holistic management keeps groundnut diseases at bay

Groundnuts favour warm, dry climates, but since they are widely planted under dryland conditions, they do require good rainfall. This presents a challenging scenario for disease management, as diseases that attack groundnuts thrive in warm, wet conditions. Lindi Botha investigates effective strategies.

- Lindi Botha

This year's groundnut season will no doubt be remembered for its wet conditions, which not only hindered harvesting operations but resulted in an increase in disease pressure.

Dr Belinda Janse van Rensburg, a researcher at the Agricultural Research Council's (ARC) Grain Crops Institute (ARC-GCI), notes that while there are a host of diseases that affect groundnuts, the most important are early leaf spot and sclerotium stem rot.

“Both of these diseases are difficult to control and are particularly devastating when the weather is warm and the soil is moist,” she explains.

An additional infection to avoid is that of aflatoxins. While they don't impact yield, the repercussions of such an infection are considerable. When crops that contain aflatoxins are consumed by humans or livestock, they can have substantial negative health effects.

Contaminated groundnuts consequently need to be removed, which reduces the size of the marketable crop. Farmers therefore need to implement strategies to prevent this fungus from taking hold in their crops.

THE RIGHT START

Diseases in groundnuts can be classified as leaf, stem, and pod diseases and, in addition to these, particular viral diseases are also encountered. Management includes chemical and biological applications, cultural management, and breeding for resistant varieties.

A key factor preventing diseases in groundnuts is crop rotation, the best of which is where a grass fallow is followed by groundnuts.

According to research done by the ARC-GCI, fewer diseases are present in groundnuts following a grass crop. Groundnuts also generally produce a better crop on fields that have been fallowed.