Stem Rot A dry rot girdles the stem at ground level causing wilting and death. Black pea-like structures are produced in the stem and these may persist for many years in the soil. Disease development is enhanced by cool wet weather. This disease is usually more of a problem on older plants. Dark brown spots, with dark concentric rings, develop on the oldest leaves.
Infected leaves die resulting in early defoliation and sunscalded fruit.
On fruits, the spots begin at the stem end. The spots develop into black leathery sunken areas which may have concentric rings. The disease overwinters in infected refuse and is enhanced by heavy dew, rainfall, and low vigor plants. Late Blight Irregular, greasy appearing, grayish areas develop on the leaves. The areas expand rapidly during moist conditions.