1. Symptoms: this insect pest is often found in high temperature and dry seasons. It mainly damages the flowers of Viola tricolor with nymphs and adults, which makes the plants appear gray spots. When the harm is serious, it will curl up the petals and even make the flowers wither in advance.
2. Prevention and control method: insecticide can be used to kill pests when they occur, and 2.5% deltamethrin 4000 times solution or fenitrothion 1500 times solution can be used for spray treatment. Spray once every 10 days, not too often.
1. Symptoms: this disease is easy to occur in hot and wet weather. The edge of the leaf is brown when the disease occurs, and there will be brown or light white spots on the leaf.
2. Prevention and control methods: in the early stage of the disease, isolate the diseased plant immediately and destroy it. Meanwhile, spray 50% thiophanate methyl in time to sterilize the plant to avoid the infection of healthy plant by diseased plant.
1. Symptoms: this disease is mainly manifested by round or irregular brown spots on the leaves, large areas of the periphery turn yellow, and small black spots around.
2. Prevention and control method: disinfect the soil of the seedbed and the place before potting. Close observation shall be carried out after planting, and the diseased plants shall be destroyed in time to prevent infection to healthy plants.
