Rice sheath blight picture and prevention methods, rice sheath blight is also known as moiré, commonly known as flower foot stalk, rotten ankle, eyebrow spot. It is caused by Rhizoctonia solani infection, and it occurs under high temperature and high humidity conditions. Sheath blight is a serious disease in the southern rice region and is one of the major diseases in rice production. The disease prevented the rice from heading, or the number of grains in the head was higher, and the grain weight decreased. Jinggangmycin, thiophanate-methyl, etc. can be used for prevention and treatment.
According to the production characteristics of various rice areas in Baoshan City, under the premise of high yield, high quality and moderate maturity, rice varieties with moderate tillering ability, compact plant type and narrow leaf type should be selected to reduce the shading effect in the field. Increase permeability and reduce air relative humidity, and improve rice plant disease resistance.
Reasonable close planting, the degree of occurrence of rice sheath blight is closely related to the size of rice population; the larger the population, the heavier the disease. Therefore, proper thinning can reduce the density of field population, improve the permeability between plants, and reduce the humidity in the field, so as to effectively reduce the occurrence of diseases and prevent lodging.
Salvage sclerotia and reduce the source of bacteria. It is necessary to salvage a large area every season and bring it out of the field.
Strengthen cultivation management, apply sufficient base fertilizer, apply fertilizer and early application, not apply partial nitrogen fertilizer, increase application of phosphorus and potassium fertilizer, adopt formula fertilization technology, so that rice does not leave leaves in the early stage, not in the medium term, and not in the later stage. Irrigation should be done in shallow water, enough in the field, roots in the field, heavy in the field, light in the field, wet in the long ear, no water loss, prevention of premature aging, and master the principle of “pre-shallow, medium-sun, and post-wet†.
The compounding agent of Jinggangmycin with Bacillus subtilis or Bacillus cereus, such as striatum, has a longer potency than Jinggangmycin and can be used. Some azole fungicides such as propiconazole, diniconazole and hexaconazole have good effects on the control of sheath blight, and have a long-lasting effect. The azole fungicides such as diniconazole and propiconazole have an effect on the formation of gibberellin in rice, and can inhibit the elongation of rice stems.
However, these bactericidal pesticides are used for long-term use in the top three extensions of rice, especially for excessive use, which may affect the lengthening of these internodes, which may cause poor heading of rice and necking phenomenon, including diniconazole. The inhibition of the drug system is more obvious. A compound of trimethoprim or difenoconazole and a triazole such as propiconazole or myclobutanil can be used before and after rice heading.
Rice sheath blight mainly harms the leaf sheath, followed by the leaves, and the panicle is also severe in severe cases. At the beginning of the disease, the leaf sheath produces dark green water-like small spots near the surface of the water, and then expands into an elliptical shape, resembling a cloud-like shape, and multiple lesions merge into a large marking. The center of the lesion is grayish green or grayish white, and the edges are dark brown and moist. When wet, the white spider silky mycelium can be seen in the diseased part. The mycelium accumulates in the later stage to form sclerotia, which adheres to the lesion and is easy to fall off.
The disease is caused by fungi, and the pathogen is Thanatephorus cucumeris. The pathogens overwinter in rice fields and are the primary source of infection. During spring irrigation, the overwintering sclerotia floats on the water surface with the floating debris and slag, and adheres to the rice plant to infect and form lesions. The pathogens on the lesion spread between the rice groves by contact with adjacent rice plants.
The sclerotia formed by the diseased part falls into the field and floats with the water to re-infect. Before the heading, the fresh hyphae of the diseased part of the diseased area lived in the lateral direction. After heading, the main leaves along the surface of the rice straw stalk and the leaves spread and invaded, and the infection from the ear to the heading stage was the fastest. The single disease occurred from the heading to the milking stage. . Early rice sclerotia became the main source of late rice.
Disease treatment method
(1) Agricultural control: No varieties of immunity and high resistance have been found. The more resistant varieties are II You 906, D You 68, Longjing No. 7, Zhongyu 898, Baonong 12 and Crystal No. 3. When ploughing in spring, 70%-80% of the sclerotia in the field floats in the sleep slag. When the shovel is in peacetime, the slag is taken out of the scum to be burned or buried in the field; the ward avoids the disease and returns to the field; Weeds; apply enough base fertilizer, apply top dressing early, control the amount of nitrogen fertilizer, increase the application of phosphorus and potassium fertilizer, prevent the sudden emergence of seedling stage, late length and greed; The principle of dry, wet and wet irrigation is implemented after booting.
(2) Chemical control
1 After 15-20 days of rice planting, use 3,500 grams of rice stalks per 667 square meters and mix 400 kilograms of fine soil, evenly spread into the rice fields to prevent the disease.
2 The field with early onset and heavy disease is controlled by the application of the disease when the disease rate reaches 10%-15% at the end of the tillering period. 10-15 days after the first application, if the disease is still developing, it needs to be prevented again. For the general incidence of the field, master the application of the disease when the disease plexus rate reaches 20% at jointing to booting stage. The agent is selected from 500-1000 times solution of Guangfuring water or 100 ml of 5% Jinggangmycin, and 50 liters of water is sprayed. In addition, 50% thiophanate-methyl or 50% carbendazim WP can be used for every 667 square meters, 30% of the WP can be 50-75 grams, 50% methyl chlorpyrifos (Liques) or 33% of the moldy net wettable powder 200 grams, plus 50 liters of water spray.
3 When the disease is heavier, you can use 20% carbendazim emulsion 130-150 ml per 667 square meters, or use 75% carbendazim WP 75g to synergize with the different rice stalks, and can cure blast disease. .
4 for every 667 square meters with 10% rusting amine emulsion 250 ml, or 25% Wo Sui Ning wet powder 50-70 g, add water 75 liters spray; 77% protection Fengan (copper hydroxide) WP 700 times solution, Or Lvzhou 98 rice-specific 600 times solution is used once at the beginning of the booting stage and at the end of the booting stage; 25% of the enemy milk oil 2000 times in the rice booting stage can effectively control rice sheath blight and leaf sheath spoilage Disease, rice smut and rice smut.
5 5% Anfu 100 ml per 667 square meters, spray once each at the heading stage and 9 days after heading.
6 full panicle is a new thiazolyl hydroxy N-benzamide fungicide, with 26.5% square meter of 225 ml of panicle suspension 225 ml and 300 ml per 667 square meters. It is safe for rice growth and has good defense against sheath blight. effect.
7 Fluoroamide (also known as Wangjiaduo, flubendiamide) is used to control the diseases caused by certain basidiomycetes fungi, and the effect of controlling rice sheath blight caused by Rhizoctonia is good, the effect of drug effect is long, and rice is safe. And can increase the rice seed setting rate. For every 667 square meters, 20% fluoroamide can be used as a municipal powder 100-125 grams, 75 kilograms of water is added, and the mixture is fully mixed and sprayed, and the focus is sprayed on the base of rice. Spray one dose each time during the rice tillering period and the water channel breaching period.
Rice sheath blight is common in countries where rice is grown in Asia, the Americas, and Africa. There are distributions in various rice areas in China, but the rice areas in the south of the Yangtze River are common, and early, middle and late rice can occur, causing a significant decrease in seed setting rate and 1000-grain weight, and even the plants are dying. Dwarf varieties are more seriously affected. Due to the large area and high frequency of epidemics, the losses caused by it often exceed that of rice blast.
The occurrence of rice sheath blight is affected by a combination of factors such as the number of field bacteria, climatic conditions, disease resistance, rice growth period and field management. The incidence of rice sheath blight in our province is: light in early rice; when the temperature in the middle season of single-season rice and late rice is low, the field occurs less; after entering July, the rice tiller increases, the density increases, and the temperature rises. Rice sheath blight begins to occur and expands.
After mid-July, the single-season rice in our province has entered the jointing and booting stage from south to north, the field is sullen and the humidity is high. At this time, the high temperature season, the occurrence of sheath blight will increase rapidly, and the disease rate and disease strain in the field will increase. The rate is accelerating, and it is more prone to epidemic in the case of continuous rainy weather; until the middle and late stages of rice filling, the occurrence of sheath blight will gradually decrease as the field humidity decreases.
The prevention and control of rice sheath blight should be based on the comprehensive prevention and control technology based on agricultural control.
First, we must do a good job in cultivation and control of diseases centered on fertilizer and water management. Rice should be properly drained and irrigated in the growing season, and the water control principle should be implemented. The principle of “pre-shallow, medium-sun, and post-wet†should be implemented. It is necessary to avoid long-term deep irrigation, prevent excessive drying of the field, promote the robust growth of rice plants, and control the pattern. The degree of disease.
The second is chemical control. The spread of sheath blight in the field mainly depends on the water flow. The hyphae in the densely planted rice stalks can also spread and spread, generally in the tillering period to the end of the jointing stage, mainly in the lateral expansion between plants or clusters, also known as horizontal expansion, leading to the field. The rate of diseased plants and the rate of diseased plexus increased. Later, the diseased part developed from the lower sheath and the upper leaf sheath and the upper leaves, which damaged the upper functional leaves of rice and increased the number of rice grains.
Therefore, the chemical control of sheath blight should be carried out in two periods. The first period is from the tillering of rice to the end of tillering. When the incidence of plexus reaches 5%, the application is to kill the aerial hyphae and control the spread of the disease. The second period is from rice jointing to booting stage, when the disease plexus rate reaches 10%, the drug control is to inhibit the formation of sclerotia and control the development of diseased upper sheath and leaf, and protect the upper three functional leaves of rice from invasion. dye.
At present, there are many drugs for controlling sheath blight on the market, such as hexaconazole, Jinggang·hexazol, Jinggang·wax, and tebuconazole, which have outstanding effects on rice sheath blight.
Before the rice tillering period, that is, before the rice is sealed (the sheath blight is not onset or in the early stage of the disease), 40 ml of 10% hexacondiol per acre is 20-30 kg of water, or after rice is blocked at the end of the rice tillage ( The sheath blight enters the rapid expansion period), using 10% octozool 55 ml per acre for 30-40 kg of water. When the morning dew is not dry, the coarse mist is sprayed on the lower part of the rice, which can effectively prevent and control the occurrence of rice sheath blight.
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