Symptoms
Sub-circular reddish-brown to dark spots on the upper leaf surface, each ringed by a yellow halo, appearing first on lower leaves. Heavy spotting causes early defoliation and reduced pod fill.
Prevention
Rotate away from groundnut for two to three seasons and plant tolerant varieties. Bury crop residue and avoid dense canopies that hold leaf wetness.
Treatment
Organic
Spray sulphur or a copper-based fungicide at first spots and remove fallen infected leaves. Maintain plant vigour with balanced nutrition.
Chemical (last resort)
Apply chlorothalonil or a tebuconazole-based fungicide on a 14-day schedule from early symptoms. Rotate groups and observe PHI on the edible pods.
Affects 1 crop
Sources
MARDI Groundnut Production Guide; DOA IPM Manual