Causes of rice false smut and comprehensive control methods: According to the data, rice smut is a fungal disease that occurs in the late stage of rice. It has been widespread in rice areas in various regions of China in recent years and has been increasing year by year. It has become one of the main diseases of rice. . Rice false smut occurs only in the panicles after flowering from the flowering stage to the milky stage, and is mainly distributed in the middle and lower parts of the rice ear. Rice false smut causes the rice grain weight to decrease, the yield to decrease, the glutinous rice and broken rice increase, and the rice yield and quality decrease. This germ contains human, animal, poultry toxic substances and pathogenic pigments, which can cause direct and indirect damage to people.
Rice false smut is also known as false smut, green smut, silage, blight, and "bumpy disease". As early as in the "Compendium of Materia Medica" of Li Shizhen of the Ming Dynasty, there was a record of the fruit body of the rice smut. The disease occurs in more than 30 countries in Asia, the Americas and Africa, as well as in various rice areas in China. The general incidence rate of panicles is 4% to 6%, which is more than 50%, the incidence rate of grains is 0.2% to 0.4%, and the high rate is more than 5%. It not only increases the rate of glutinous rice, cyan, and broken rice, but also reduces the yield of local fields by 20% to 30%. When the rice contains 0.5% of the granules, it can cause symptoms of human and animal poisoning.
Causes of rice false smut:
The sexual state is Claviceps oryzae-sativae Hashioka, belonging to the genus Ascomycete; the asexual state is Ustilaginoidea virens (Cooke) Takahashi, and the nickname is U. oryzae (Patou.) Bref. The sclerotium spores are dark green, spherical or elliptical, with a diameter of 4~8mm×4~7mm. The surface has a ridge-like protrusion, which is formed by thick and thin hyphae, concentrated protoplasm and thickened cell wall. After germination, it produces short, coarse, solitary or branched, separated hyphae, and several conidia of elliptical or inverted pear shape are produced at the top, with a diameter of 4~5mm, and the conidiophore is thick. 2.0~2.5mm. The sclerotium is flat and long oval, initially white, and becomes black after maturity, up to 2~20mm. Usually, the endogenous sclerotia of a diseased grain is 2~4, and it is most common to cover the grain on both sides of the diseased valley. It is easy to fall off when mature. In the second year, the sclerotia that landed in the soil produced several meat protons. The sub-seat has a handle of about 1 cm in length and a spherical or cap-like top. The ascospore shell is spherical, buried in the top surface of the sub-seat, and the opening is exposed, so that the top surface of the sub-seat is dome-shaped. The ascus has a long cylindrical shape, is colorless, and contains eight colorless filamentous ascospores.
The incidence of rice false disease:
Rice smut disease is overwintering on the ground with sclerotia. In the second year from July to August, the sclerotia begins to take place, and the upper sac has a large number of ascospores. The sclerophyllum spores can also be found in the damaged grain and the gluten. Over the winter, it can germinate at any time to produce conidia and maintain the germination power for 6 months. Both ascospores and conidia can be spread by airflow, invading flower organs and young plants. In the northern rice region, it occurs only once a year. In the southern rice region, the sclerotium spores on the early rice are used as the re-infection source to infect the late rice, or the sclerotium spores on the early heading rice may become the invasive source of the late-raised rice. . Some people think that the genus Digitaria marginita L. is the intermediate host of the rice smut. The pathogen invades the ovary, style and stigma at the booting stage; in the later stage, it invades the appearance and peel of the young caryopsis, spreads into the endosperm, and then proliferates in large quantities and forms spores. The diseased grains appear at the end of the rice flowering stage to the early stage of grain filling. Artificial vaccination showed that the germination of the sorghum spores could directly infect the rice buds and radicles, causing the phylogeny, and the nature was similar to that of the wheat smuts infected by the seedlings.
Rice crack disease prevention and treatment methods:
1. Prevention timing:
Generally, it is required to use the medicine twice. The first leaf of the stalk of more than 1/3 of the whole field is taken out at the first time, that is, it is commonly used as a "big package" (about 5-7 days from the earing time). At the peak of the initial infection, so at this time seize the opportunity to use pesticides in a timely manner, the best control effect. The second time, the drug was reused at the beginning of the rupture to consolidate and improve the control effect.
2. Control agents:
(1) Norway 86.2% cuprous oxide (master copper), diluted 1500 times acre with 20-30 grams. Low cost and long duration.
(2) 25% of the rice koji WP can be used in 40-60 grams;
(3) 20% powder rusting WP can be used in 75-100 grams;
(4) 18% chlorhexone WP can be used in 150-200 grams;
(5) Copper high 27.12% suspending agent; 800-1000 times before the onset or initial spray 2-3 times, avoiding flowering and earing stage (6) 50% carbendazim wettable powder with 100 grams;
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