Management Of Important Grain Diseases

Plant pathology scientists Dr Gert van Coller and Dr Bradley Flett spoke to Pieter Dempsey about some diseases that pose significant threats to South Africa’s maize and wheat production, and how to control them.

- Pieter Dempsey

FAST FACTS

After a hiatus of almost 20 years, several cases of maize eyespot were reported during the 2020/21 production season.

Yield losses caused by maize eyespot are often not significant enough to warrant treatment via the application of expensive fungicides.

Infection by powdery mildew in wheat can cause yield losses as well as a decline in grain quality.

Maize is the most important field crop in South Africa, making up more than 50% of the country’s total field crop production. The use of improved seed technology and sustainable farming practices have both contributed significantly to the management of pest and disease damage to maize crops. However, the industry remains vigilant about the emergence of new threats to the production of this staple crop.

RETURN OF AN OLD FOE

During the 2020/21 production season, several cases of maize eyespot, which is caused by the fungus Aureobasidium zeae, were reported in a number of production regions. These were the first known cases of the disease since it was initially recorded in the more humid production areas of the south-eastern Free State, northern KwaZulu-Natal, and south-eastern Mpumalanga during the 1992/93 season.

Dr Bradley Flett, senior plant pathologist with the Agricultural Research Council’s (ARC) Grain Crops Institute, says that during the 1993/94 season, eyespot was more widespread and its severity greater, particularly in the Heidelberg district.