First, consider whether there is a lack of nutrition: 1. Nitrogen deficiency. Peach trees are characterized by a lack of nitrogen, and their leaves are light green to yellow. The old leaves under the new shoots are the first to get sick, the leaves turn yellow, and the petiole, leaf margin and vein turn red. In the late stage, mesophyll between veins produces reddish-brown spots, and there are many spots. When the condition is serious, mesophyll is purple-brown and necrotic. ...