Detailed Guide to Identifying and Controlling Common Rice Pests and Diseases
Common Rice Pests and Diseases and Their Control Methods
1. Rice thrips: Rice thrips are very small. The adults are dark brown, have wings and crawl very quickly. Their life cycle has three stages: egg, nymph and adult. The nymphs resemble the adults, are pale yellow and very small, have no wings, and often curl up on the tips of rice leaves, piercing and sucking the sap of the rice leaves. The damaged rice leaves lose water and curl, the rice seedlings turn yellow, the rice leaves have scattered white spots, and the central leaf shrivels, looking from a distance as if scorched by fire. At flowering time, rice thrips gather
Control methods: Because rice thrips are very small, they generally do not easily attract attention. They are usually discovered only when rice is severely damaged and large numbers of leaves curl. Therefore, timely inspection is necessary to eliminate rice thrips at the larval stage. Apply 40% dimethoate emulsion at a dilution of 1500-2000 times per mu. After applying the pesticide in both seedling fields and main fields, a water layer must be maintained. After controlling rice thrips, apply a quick-acting fertilizer to promote the recovery of seedling and tiller growth.
2. Rice planthoppers: Among rice planthoppers, the brown planthopper and the white-backed planthopper cause the greatest damage. Rice planthoppers generally hide inside the leaf sheaths and stem tissues in the lower part of rice plants in the middle of the paddy field, piercing and sucking the sap of the rice stems. Irregular elongated brown spots appear on the damaged parts of the rice plants, and in severe cases the base of the rice plant turns dark brown. Because the stem tissues are destroyed, nutrients cannot rise, and the rice plant gradually wilts and dies, or lodges. After rice heading, the lower rice stems age, and rice planthoppers move to the upper part to suck on the tender panicle necks, causing rice grains to become empty shells or half-filled grains. At the same time, the brown planthopper can transmit rice virus diseases.
Control methods: 1. Oil-drip insect killing. Drip 400-500 grams of waste diesel oil or waste engine oil per mu, maintain a shallow water layer of 20 cm in the field, and drive the insects manually; the insects fall into the water, touch the oil and die. After treatment, replace with clean water. Do not use this method after the booting stage. 2. Apply poison soil. Apply 1.5 kg of dimethoate powder and 2 kg of moist fine soil per mu. 3. Spray with pesticide: use 0.5 kg of 40% dimethoate emulsion added to 800-1000 kg of water for spraying.
3. Rice skipper: The rice skipper, also called the leaf-rolling worm, often occurs once every few years, causing large-scale reductions in rice yield. The adult is a reddish-brown butterfly. The larvae damage rice. After rice leaves are damaged, they become incomplete and broken, and in severe cases only the leaf veins remain, making rice clumps look like pot-scrubbing brooms. Especially after damage at the booting stage of rice, the larvae spin silk to bind rice leaves together, causing the rice panicles to curl and be unable to emerge, affecting yield.
Control methods: 1. Apply 2 kg of 2.5% trichlorfon powder per mu for dusting, or 1 kg of methyl parathion-trichlorfon powder plus 10 kg of fine soil as poison soil. 2. Spray with 150 g of 90% crystalline trichlorfon added to 80-100 kg of water.
4. Rice leaf roller: When the larvae are slightly larger, they begin to spin silk in the central leaf of rice, rolling both sides of the leaf into a tubular worm shelter. The worms hide inside the shelter and feed on the leaf mesophyll and upper epidermis. After heading, they move into the more tender leaf sheaths to cause damage. In severe cases, only the transparent, whitish epidermis remains of the rolled leaves, and the entire leaf dies.
Control methods: Spray with 25% DDT emulsion at 250 times dilution, or 90% trichlorfon at 1000-1500 times dilution. The control timing should be before the third instar of the larvae, and application in the evening gives the best effect. After control, check the effect; if the insect population density is the same as before, treat once more.
Control methods: Because rice thrips are very small, they generally do not easily attract attention. They are usually discovered only when rice is severely damaged and large numbers of leaves curl. Therefore, timely inspection is necessary to eliminate rice thrips at the larval stage. Apply 40% dimethoate emulsion at a dilution of 1500-2000 times per mu. After applying the pesticide in both seedling fields and main fields, a water layer must be maintained. After controlling rice thrips, apply a quick-acting fertilizer to promote the recovery of seedling and tiller growth.
2. Rice planthoppers: Among rice planthoppers, the brown planthopper and the white-backed planthopper cause the greatest damage. Rice planthoppers generally hide inside the leaf sheaths and stem tissues in the lower part of rice plants in the middle of the paddy field, piercing and sucking the sap of the rice stems. Irregular elongated brown spots appear on the damaged parts of the rice plants, and in severe cases the base of the rice plant turns dark brown. Because the stem tissues are destroyed, nutrients cannot rise, and the rice plant gradually wilts and dies, or lodges. After rice heading, the lower rice stems age, and rice planthoppers move to the upper part to suck on the tender panicle necks, causing rice grains to become empty shells or half-filled grains. At the same time, the brown planthopper can transmit rice virus diseases.
Control methods: 1. Oil-drip insect killing. Drip 400-500 grams of waste diesel oil or waste engine oil per mu, maintain a shallow water layer of 20 cm in the field, and drive the insects manually; the insects fall into the water, touch the oil and die. After treatment, replace with clean water. Do not use this method after the booting stage. 2. Apply poison soil. Apply 1.5 kg of dimethoate powder and 2 kg of moist fine soil per mu. 3. Spray with pesticide: use 0.5 kg of 40% dimethoate emulsion added to 800-1000 kg of water for spraying.
3. Rice skipper: The rice skipper, also called the leaf-rolling worm, often occurs once every few years, causing large-scale reductions in rice yield. The adult is a reddish-brown butterfly. The larvae damage rice. After rice leaves are damaged, they become incomplete and broken, and in severe cases only the leaf veins remain, making rice clumps look like pot-scrubbing brooms. Especially after damage at the booting stage of rice, the larvae spin silk to bind rice leaves together, causing the rice panicles to curl and be unable to emerge, affecting yield.
Control methods: 1. Apply 2 kg of 2.5% trichlorfon powder per mu for dusting, or 1 kg of methyl parathion-trichlorfon powder plus 10 kg of fine soil as poison soil. 2. Spray with 150 g of 90% crystalline trichlorfon added to 80-100 kg of water.
4. Rice leaf roller: When the larvae are slightly larger, they begin to spin silk in the central leaf of rice, rolling both sides of the leaf into a tubular worm shelter. The worms hide inside the shelter and feed on the leaf mesophyll and upper epidermis. After heading, they move into the more tender leaf sheaths to cause damage. In severe cases, only the transparent, whitish epidermis remains of the rolled leaves, and the entire leaf dies.
Control methods: Spray with 25% DDT emulsion at 250 times dilution, or 90% trichlorfon at 1000-1500 times dilution. The control timing should be before the third instar of the larvae, and application in the evening gives the best effect. After control, check the effect; if the insect population density is the same as before, treat once more.