Rice blast affects rice quality how to control rice blast

Rice blast is a disease caused by Botrytis cinerea. Rice can occur in all growth stages and parts, which can be divided into seedling blast, leaf blast, leaf neck blast, node blast, panicle neck blast, branch blast, grain blast and so on.

Rice blast

① seedling blast: mostly occurred in the 2-3 leaf stage of rice seedlings, the base of rice seedlings was infected with bacteria, appeared gray and black, and the rice seedlings finally curled and withered.

② leaf blast can occur from the third leaf stage to the panicle stage, and there are four types of disease spots. Chronic type: also known as typical disease spot, the most common, disease spot is fusiform, the outermost is yellow halo, the inner circle is brown, the center is gray-white, rice leaves have brown necrotic lines at both ends; acute type: disease spot is dark green, water stain, nearly round or irregular spot. Varieties are susceptible to disease, more nitrogen fertilizer, high incidence when meteorological conditions are suitable; white spot type: disease spot is near round spot, high incidence under adverse weather conditions, conditions turn better, can be transformed into chronic type and acute type; Brown spot type: small brown spots, between leaf veins, mostly on disease-resistant rice varieties and lower old leaves. The first two of the above four disease spots are sporulation disease spots, which directly affect the occurrence and development of the disease.

③ panicle neck blast: occurs in the neck of the panicle from the main panicle stem to the first branch branch of rice, showing brown dots at first, and then ring-shaped expansion, showing gray or dark green. The disease occurs early and often forms white ears, which seriously affects fruiting, grain weight and rice quality.

[incidence regularity] Magnaporthe grisea mainly overwintered on diseased grain and diseased rice straw by mycelium and conidia, and spread by airflow. Seed-borne bacteria can easily cause seedling blast of southern double-cropping early rice. From tillering to booting stage, it is often low temperature and rainy, which is easy to cause leaf blast. It is rainy before heading, which is easy to cause neck blast. Mountain area, long-term deep irrigation, cold soaking field, partial application of nitrogen fertilizer and so on are easy to cause rice blast.

[control] the prevention and control of rice blast should focus on planting resistant and high quality rice varieties, based on fitness cultivation and supplemented by chemical protection.

(1) rational use of disease-resistant rice varieties. Magnaporthe grisea has significant physiological differentiation, and planting rice varieties with high resistance in a large area is easy to lose disease resistance, so we should pay attention to selecting disease-resistant varieties according to local conditions, rational distribution of varieties, and avoid single planting in large areas.

(2) Scientific field management. Cultivate strong seedlings, apply sufficient basic fertilizer, increase potassium fertilizer, zinc fertilizer, organic fertilizer, skillfully apply panicle fertilizer, and sun-dry the field at the right time.

(3) seed treatment. The seeds were soaked in 1000 times of 10% 401 antibacterial agent for 48 hours or 80% 402 of 2000 times of antibacterial agents for 48 hours or directly for 72 hours, or the seeds were soaked in 500 times of 20% tricyclazole wettable powder for 24 hours, and then washed and germinated.

(4) Pesticide control. Rice leaf blast should be protected by spraying at the initial stage of the disease (when the diseased leaf rate is 3%), panicle blast should be protected at the early stage of rice heading, and the spraying times should be determined according to the weather. Medicament selection: 75% tricyclazole wettable powder 30 g or 40% Fuji 1 100 g or 40 g distemper EC 150 g 200 g per mu. In order to ensure the effect, the water consumption of 50 kg per mu of rice should be guaranteed, and the drug dosage should not be increased blindly.