Brown Spot- Septoria glycines
Primarily an early season leaf disease. Cotyledons, primary leaves and lower trifoliolates show brown to red pinpoint spots up to 1/4 inch. Some may grow together and become irregularly shaped spots. Look for black dots, “pycnidia,” in center of mature spots. Severe infection can cause leaves to yellow and drop early, especially the lower canopy. Spores are splashed or wind blown to wet leaves, mostly in mid-spring. It can develop in warm moist periods at any time. Hot, dry weather stops this disease, but it can develop again before plants mature.
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