Potato plants with late blight, caused by Phytophthora infestans.

The most important potato leaf diseases are late blight (Phytophthora infestans), early blight (Alternaria solani) and brown spot or "malroes" (Alternaria alternata). Yield losses for potato blight range from 40 to 100% in unsprayed potato crops, with an increase in virulence from these pathogens. The ARC-VOP is currently evaluating quick, reliable screening methods against these diseases for the potato breeding scheme at Roodeplaat. Newly developed cultivars are screened for tolerance to late blight in the field, while detached leaf assay and greenhouse trials are used to screen cultivars for tolerance to early blight and brown spot. Plant pathogens are rapidly developing tolerance to fungicides used to control them. This is a growing problem world-wide. Part of our research includes screening of Alternaria species present in each of the potato production areas for tolerance to commonly used fungicides. The data generated will be used to provide advice to farmers on which classes of fungicides to avoid using in their areas.

Contact: Dr Rene Sutherland or Dr Elsie Cruywagen

​ ​Potato plants with leaf spots caused by Alternaria species.

>>> Back to Fungal Diseases​​​