At present, rice mainly attacks diseases in Guangdong.

Rice bacterial streak, rice blast, sheath blight and bacterial blight are four main diseases in late rice production in Guangdong, which mainly damage plant leaves in the early and middle stages of rice growth. There are many typhoon rice areas along the coast of our province, while rice blast and bacterial leaf spot are the main damage in hills and mountainous areas. In this paper, the occurrence period, characteristics and control methods of bacterial leaf spot, rice blast and sheath blight are briefly described as follows:

Bacterial leaf spot of rice has a tendency to spread in Guangdong in recent years. The disease begins in seedling stage and flourishes in young panicle differentiation stage. Frequent wind and rain in Taiwan, flooded paddy fields or excessive application of nitrogen fertilizer are the environmental causes of the disease. At the beginning, the disease spot on the leaf surface of the diseased plant showed a translucent infiltrating short strip or long strip spot, and then turned yellowish brown, and the bead-like bacteria overflowed on the disease spot, which was not easy to fall off after drying up. The control of seedling field should be applied once at the three-leaf stage of seedling and before transplanting, and the flooding of seedling field should be stopped. Field control, spraying 2-3 times at the initial stage of the disease, once every 7 days. 25% Ye Qing Shuang 7-100g per mu, or BC 50-70ml, or 50% carbendazim 30-40g, 50 kg water spray control.

Rice blast is easy to occur in the middle and late tillering stage. The large temperature difference between day and night, the disclosure of water in leaves and the cool temperature are the environmental factors that induce the disease. The diseased plant leaves produce water-stained brown spots at the initial stage, and the susceptible varieties quickly form round or oval brown spots, which are dense and scorched in severe cases. To prevent the occurrence of the disease, one is to plant disease-resistant varieties; the other is not to apply too much nitrogen fertilizer in the field, pay attention to the combination of nitrogen, phosphorus and potassium, irrigation shallow water to promote tillering after transplanting, open ditches and drain in time before the peak tillering stage, and promote the health of seedling plants. The focus of the control of leaf blast is in the peak tillering stage, spraying high-efficiency fungicides immediately at the initial stage of the disease, adding 75-100 ml of rice per mu, or 40% Fuji No. 1 (Rice blast Ling) 50-75 ml, or 20% tricyclazole 50-70 grams, spraying 50 kg of water. If the disease is serious, spray it again every 7 times for 10 days. The key points for the control of panicle blast are the breaking stage and full heading stage.

Sheath blight can occur in the whole growth period of rice, and the damage is serious from the peak tillering stage to booting stage. High temperature, high humidity and partial application of nitrogen fertilizer will promote the epidemic of the disease. The leaf sheath near the water surface of the diseased plant was damaged to form oval or moire gray-green to grayish brown spots, and in severe cases, the leaves became yellow and withered. The occurrence of the disease can be reduced by strengthening cultivation management in production, draining and drying the field at the peak tillering stage, reducing ineffective tillers and lowering field temperature. When the incidence reaches 20%-30%, use 5% Jinggangmycin water 100ml or 20% powder 30-40g, spray 50-70kg of water.