Phytophthora leaf spot

Symptom

The disease is caused by the fungus Phytophthora. Lesions initially develop along the main veins rather than on the leaf blade itself, and they rapidly expand along the veins. During wet and dry seasons, gray, concentric-ringed structures often form within the lesions, giving a water-soaked and swollen appearance. The infection spreads upward to the upper parts of the leaves, petioles, and stems, causing wilting. In addition, the disease often attacks the stem near the soil surface and the lower part of the plant. Initially, grayish, water-soaked spots appear, often encircling the stem. These lesions soon turn dark brown, expand widely, and the tissue becomes soft and decayed. Severe infection leads to leaf drop and ultimately plant death.