The main cause of the disease is that the plant is infected by bacteria. The infected fungi have a very strong vitality. They can also survive the cold winter in the plant. When the weather is warm in the spring next year, they start to recover their vitality and invade the plant growth. At the beginning, it gradually changes from grayish brown to grayish white from the middle, and gradually sinks down. Its edge also has a yellow brown line. The back of the leaf also grows yellow powder like rust, which is the source of bacteria.
1. This is often caused by too much water, which makes the root system of plants very vulnerable and poor growth. Therefore, it is necessary to cut off the position of the lesion first, and then burn the cut leaves. If it is planted more intensive so need to dredge it, to avoid it planting too dense.
2. In the spring season with multiple occurrence, it needs to spray some Bordeaux solution properly for protection. If the disease has already occurred, it can also spray with the solution of Triadimefon and water. Or use chlorothalonil and tobuzin to spray the whole plant.
