Detailed Explanation of Key Technical Points for Controlling Two Diseases and Three Pests of Rice

The two diseases and three pests of rice refer to rice blast, sheath blight, rice stem borers, rice planthoppers, and the rice red-spotted black spittlebug. They cause great harm to rice and should be given attention for control.

Rice blast: Long-term deep water irrigation or excessive drought, and one-sided application of nitrogen fertilizer lead to severe rice blast. There are three susceptible periods in the life of rice, namely the seedling stage, the peak tillering stage, and the heading and full heading stage. Neck blast has the greatest impact on rice yield and should be prevented early at the breaking stage and full heading stage. Rice blast is divided into: seedling blast, leaf blast, node blast, neck blast, and grain blast. Rice blast control should adopt comprehensive control measures centered on planting disease-resistant high-quality varieties, based on healthy cultivation, and supplemented by chemical protection. (1) Rational use of disease-resistant varieties. (2) Scientific field management: cultivate strong seedlings, apply sufficient base fertilizer, increase potassium fertilizer, zinc fertilizer, and organic fertilizer, skillfully apply panicle fertilizer, and drain the field at the appropriate time. (3) Seed treatment: soak seeds in 1000-fold dilution of 10% 401 antibacterial agent for 48 hours, or soak in 2000-fold dilution of 80% 402 antibacterial agent for 48-72 hours and then germinate directly, or soak in 500-700-fold dilution of 20% tricyclazole wettable powder for 24 hours, wash clean, and then germinate. (4) Chemical control: leaf blast should be sprayed for protection at the early stage of disease occurrence (when the diseased leaf rate is 3%), and neck blast should be sprayed for protection at the early heading stage, after which the number of sprays should be determined according to weather conditions. Chemical selection: 30 grams of 75% tricyclazole wettable powder per mu, or 100 grams of 40% Fuji No. 1, or 150-200 grams of 40% hinosan emulsifiable concentrate. To ensure the effectiveness of chemical control, 50 kilograms of water per mu should be guaranteed, and the dosage should not be blindly increased.

Rice sheath blight: Excessive nitrogen, dense planting, and excessive irrigation easily lead to severe occurrence of sheath blight. The control of rice sheath blight should be based on agricultural measures combined with chemical control. (1) Focus on cultivation-based disease prevention centered on fertilizer and water management. Fertilizer application should focus on stable application of nitrogen and phosphorus and increased application of potassium and zinc fertilizers. Based on the principle of applying sufficient base fertilizer and ensuring panicle fertilizer, nitrogen fertilizer should not be applied to promote seedling growth in the middle growth stage of rice. Irrigation should implement the principle of "shallow water at the front, sun-drying in the middle, and moist conditions later." (2) Chemical control: focus on protecting the last 3-4 leaves of rice plants. Application should not be too early (before the jointing stage) or too late (after the heading stage). Chemical selection: 150 milliliters of 5% validamycin aqueous solution per mu, or 100-200 milliliters of 12.5% Wenmeiqing aqueous solution, or 60-100 milliliters of 20% Wenmeiqing suspension concentrate, or 50 grams of 15% fenpropidin wettable powder, diluted with 50-70 kilograms of water for spraying. The chemical should be sprayed on the middle and lower parts of rice plants, and the key control period should be from booting to full heading stage.

Rice stem borers: including the striped stem borer, the yellow stem borer, and the rice leaf roller. Severe damage by stem borers can cause white heads. Control method: use 90 ml of 15% Leizuan emulsifiable concentrate per mu, or 90 ml of 13.5% Zuanxinpao emulsifiable concentrate, or 90 ml of 13.5% Fake emulsifiable concentrate, or 50 ml of 13.5% Juedou emulsifiable concentrate, or 40 ml of 10% Jinfo emulsifiable concentrate, or 90 ml of 20% chlorpyrifos or phoxim emulsifiable concentrate, diluted with 60 kilograms of water for spraying. Control periods for rice stem borers: (1) Striped stem borer: apply chemical control at the peak of young larvae. (2) Yellow stem borer: the first application should be at the large belly stage of rice (three days before the breaking stage), and another application can be made seven days later. (3) Rice leaf roller: apply chemical control when new small leaf rolls appear, with sufficient water and uniform spraying.

Rice planthoppers, commonly known as "mengzi," are also one of the main pests of rice. The more common ones are the white-backed planthopper and the brown planthopper. Both planthoppers migrate in from southern rice-growing areas with the southwest airflow. Generally, the white-backed planthopper is dominant in the early stage of rice, and the brown planthopper is dominant in the later stage. That is, the white-backed planthopper mainly damages from tillering to jointing stage. In affected fields, rice leaves turn yellow and tillering decreases; in severe cases, rice plants collapse in patches and die. The damage by the brown planthopper mainly occurs from booting to maturity. When damage is severe, the base of rice clumps turns black-brown and gradually the whole plant dies. Affected fields often show "yellow patches," and in severe cases the whole field turns yellow and withered, as if burned by fire. The appropriate control period for both planthoppers should begin when there are more than 50 insects per 100 clumps in the field, adopting the strategy of "suppressing the early and controlling the late" and vigorously controlling the main damaging generation. ① Spraying: options include 10% imidacloprid wettable powder, 2000-fold dilution of 25% buprofezin wettable powder, 25% metolcarb wettable powder, 300-fold dilution of 10% leafhopper powder wettable powder, and 800-fold dilution of 80% dichlorvos emulsifiable concentrate. Spraying any of these can achieve good results. ② Pouring: options include 10% imidacloprid or 25% buprofezin wettable powder at 40 grams per mu; 40% monocrotophos emulsifiable concentrate at 50 milliliters per mu, poured with a large amount of water, using 400 kilograms of water per mu. ③ Broadcasting granules or poisonous soil: broadcast 2-3 kilograms of 3% carbofuran granules or 4% leafhopper powder granules per mu into the rice field; alternatively, use 150 grams of 80% dichlorvos emulsifiable concentrate, dilute with an appropriate amount of water, mix with 20-25 kilograms of fine soil, and broadcast.

The rice red-spotted black spittlebug, also known as the red-spotted spittlebug or rice spittlebug, is commonly called "thunder fire insect" or "bubble-blowing insect." It generally moves in a scattered manner, mostly feeding in rice fields in the morning and evening, and hides in weed clusters when encountering high temperature and strong light. When outbreaks occur, adults fly in groups in the field in the evening. After feeding to satiety, adults hide on the undersides of crop leaves or in weed clusters, and damage is generally heavier at field edges than in the center. After feeding, adults continuously excrete colorless transparent liquid feces, contaminating crop leaves. Adults are active in nature, good at flying and jumping, can fly 2-3 m at a time, and have the characteristic of avoiding light when feeding. The rice red-spotted black spittlebug mostly feeds on leaf sap and flower sap in adult form on cloudy days, early morning, or evening, causing empty grains and affecting yield. Affected leaves turn red, and damage gradually worsens from the center of the field to the surrounding area, looking like fire from a distance. For nymph control, after the peak of the 3rd instar and before adult emergence, when many white foam masses are found on field ridge soil cracks, field ridge plant stems, or leaves; for adult control, when there are more than 3 insects per square meter in the rice field. The nymphs of the rice red-spotted black spittlebug live in the soil and feed on weed root sap through cracks in the soil surface. At this time, 3% carbofuran granules mixed with fine soil can be broadcast on field ridges for control. During the peak occurrence period of adults, spray for control with 600-fold dilution of 20% triazophos emulsifiable concentrate, or 400-fold dilution of 40% superspray emulsifiable concentrate, or 600-fold dilution of 40% isocarbophos emulsifiable concentrate, or 1000-fold dilution of 45% malathion emulsifiable concentrate, or 1500-fold dilution of 40% omethoate emulsifiable concentrate.