Brown spot and Black pit

• 1Symptoms on foliage
• 2Distinct dead tissue lesions of varying sizes can be observed, primarily on the lower foliage of the plant.
• 3Larger lesions often display characteristic concentric ring patterns.
• 4The disease symptoms typically develop first on the older, aging leaves located in the lower canopy, where natural leaf senescence has already begun.

Causal agents and transmission Early blight is caused by a group of species of the fungal genus Alternaria. At least two species are responsible for early blight symptoms on potatoes, A. solani and A. alternata. These fungi overwinter in the soil, on crop debris and infected tubers. They are pathogenic to Solanaceous plants, potatoes and tomatoes, but can also be considered as saprophytes. The spores are spread by the wind and rain splashing.

The disease causes damage mainly in hot, dry climates and its effects are exacerbated in irrigated crops. Early blight develops at temperatures between 20 and 30°C and with alternating dry and humid periods. High temperatures (20-25°C) on sunny days and dew at night are favourable conditions for the development of the disease. Early blight is also considered as a sign of weakness in the plant, brought about by nutritional imbalance, drought, plant senescence, insect attacks or mechanical damage.