Tianjin Caojing, a dealer of agricultural products, passed the seed micro-letter on March 26th to ask: Are rice sheath blight, rice planthoppers, and rice leafhoppers overlapping in time? What are the available control agents on the market today?
Zhang Jianzhang, product manager of Shandong Yiyi Biotech Co., Ltd. A: rice sheath blight, also known as moire. From the seedling stage to the panicle stage can be disease. Leaf sheath disease, dark green water immersed in the water near the edge of the fuzzy small spots, then gradually enlarged oval or moire, the middle was grayish green or gray brown, when the humidity is low, the middle was yellow or gray, the central tissue destruction Translucent, dark brown edges. When the disease is severe, several lesions fuse to form a large lesion, showing an irregular cloud-like spot, often causing the leaves to yellow and die. The leaves were infected, the lesions were also moire, and the edges were yellowing. When the lesions were fast, the lesions were stained green and the leaves soon rotted. Damage to stems, symptoms like leaves, yellow brown later, easy to fold. The victims of the ear and neck were initially tainted with green and later became gray and brown, often failing to head their heads. When the humidity is high, the disease minister produces a white net-like hyphae, which is then aggregated into a white mycelium cluster to form sclerotia. The sclerotia are dark brown and easily fall off. A layer of white mold is produced on the lesion under high temperature conditions.
Rice planthoppers belong to the Homoptera family. There are three main damages to rice: brown planthopper, white-backed planthopper and flyhopper. The most serious hazards are brown planthoppers and white-backed planthoppers. The early rice plants are mainly white-backed planthoppers, and the later stage are mainly brown planthoppers. The mid-late-season rice plants are mainly brown planthoppers. The planthoppers rarely direct disasters, but they can spread virus diseases in crops such as rice, wheat and corn. Long-winged adults of rice planthoppers can migrate long distances. Adults and nymphs are clustered on the stems of the lower part of the rice stalk to suck and sap. When they are disturbed, they jump to the surface of the water or flee. The phototaxis is strong, and they tend to be green and tender; The phototaxis is slightly weaker. Its field is in the rice ear stage. White-backed planthoppers live winters in Guangxi and south of Dehua, Fujian. They use their eggs to grow on their own seedlings and grasses. The winter limit is about 26 degrees north latitude. It occurs in China for 3-8 generations each year, and the damage to the single season, late rice and double cropping early rice is heavier. In the north of China, the nymph is wintering in the weeds, rice piles, or fallen leaves. In Zhejiang, the nymphs live on the weeds in wheat fields. Winters can be found in all the southern states of Fujian. It takes 4-5 generations each year in North China, 5-6 generations in the middle and lower reaches of the Yangtze River, and 7-8 generations in Fujian. Although the field damage period is later than the white-backed flycatcher, it is still the earliest stage of damage.
Cnaphalocrocis medinalis is a migratory pest, occurring from 1 to 11 generations from the north to the south. It is south of the first line of the Nanling Mountains. There is a certain amount of earthworms and a small amount of larvae that live throughout the winter all year round. Overwintering, so the vast majority of rice area in the original insect source are moved from the south. Adults have phototaxis, inhabitation tends to shading and tending to lay eggs, and fecundity at high temperature and high humidity. Generally, 40-70 eggs per female are produced. Eggs are more yields, and 2-5 are produced together. Temperature 22- 28-C, relative humidity more than 80%, egg hatching rate of up to 80% -90%. Most of the newly hatched larvae penetrate into the heart and leaves. After entering the 2nd instar, they are scabbed on the leaves and can be drilled into the panicle during the late booting period. The larvae eat 5-6 pieces of leaves, up to 9-10 pieces, and the food intake increases with the increase of the worm-infested age. The l-3 age-feeding leaves amount to only 10% or less, and the larvae leave most of the old worms in the rice tussock. The yellow leaves of the base and the leaves of the invalid tillers are full of phlegm and blood. The severity of the rice leaffolder is closely related to the climatic conditions. In the case of moderate temperature and high humidity, it favors the oviposition, hatching, and survival of larvae. Therefore, it is beneficial to rice leaf roller in rainy days and high dew and humid weather. rampant.
Rhizoctonia cerealis began to be used during the jointing stage of rice, and triazoles such as oxazole and carbazole were commonly used; leafhoppers were severe in the middle and late rice (sub-period) from July to August, and propofol could be used. Prevention and treatment of hexaflumuron, avermectin, etc.; planthoppers occur from the tillering period to the breaching period, and can be controlled by acetamiprid, kung fu, buprofezin, isoprocarb, etc.
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