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Is it the most important measure to control one piece at a time and to prevent wheat stripe rust?

Wheat stripe rust is a major epidemic disease spread by high-altitude airflow, which has the characteristics of strong suddenness, fast spread, difficult monitoring and heavy damage and loss. Generally, the production can be reduced by 20%-30%, and in serious cases, it can reach more than 50%, or even no harvest.

First, symptom identification? The main symptoms of the three kinds of rust can be summarized as "stripe rust in rows, leaf rust in disorder, and stem rust with great red spot". Stripe rust mainly occurs on leaves, followed by leaf sheaths, stems and spikes. When infected at seedling stage, pale yellow summer spore piles were produced on leaves. At the beginning of the disease, the summer spore piles are small and long, bright yellow and oval, parallel to the veins, arranged in rows, like the stitches rolled down by a sewing machine, in a dotted line shape. In the later stage, the epidermis was broken and rust powder appeared. Touch the diseased spot with your hands and leave rust powder on your hands. Black winter spore piles were produced in the late ward. The winter spore pile is short and flat, with constant fusion number, embedded in epidermis and not cracked when mature.

Second, the characteristics of harm? First, stripe rust is an epidemic, which spreads with the wind. It can spread with the air flow at a long distance and high altitude, and be blown to places hundreds to thousands of meters away without losing its activity for reinfection. Second, it spreads quickly, causing great harm and loss. Spore piles of wheat stripe rust can produce spores for 8- 10 days, and each spore pile can produce spores for 1800 per day, with overlapping generations and cross-epidemic. In the middle and late stage, the temperature in the field rises, the generation is accelerated, and spore flow is formed under the action of wind, which is easy to break out and cause disasters. After wheat is infected with stripe rust, it affects its development and grain filling, thus causing wheat grains to scratch and affecting its yield and quality.

Third, the route of transmission and the onset conditions.

Wheat stripe rust is a typical long-distance airborne disease, which mainly completes the annual infection cycle with summer spores on wheat. Its infection cycle can be divided into four links: over-summer, autumn seedling infection, wintering and spring epidemic. The summer spores produced in the summer area were blown to the wheat area by the wind, which became the initial impregnation source of autumn seedlings. Pathogens can overwinter with sick wheat seedlings. Summer spores are produced on winter diseased wheat seedlings in spring, which can spread and cause reinfection.

Planting susceptible varieties in a large area is the basic condition for the epidemic of stripe rust. However, whether stripe rust is prevalent or not depends on bacterial sources and meteorological factors, especially rainfall and humidity. Wheat was infected by Puccinia striiformis under the conditions of temperature 14- 15℃ (leaf rust 15-20℃), water droplets and water film. The pathogen grows in wheat leaf tissue, and when the effective accumulated temperature is 150- 160℃, summer spore piles are produced on the leaves. Under the premise of planting susceptible varieties in a large area, the amount of bacteria and rainfall have become two important conditions for popularization If there is more rain in April and May and the temperature is suitable, it will be beneficial to the occurrence and spread of stripe rust. If there is rain in early spring, drought in late spring or drought in early spring, the occurrence of stripe rust is light, or it is not popular in the local area. In spring, drought persists, even if susceptible varieties are planted in a large area, stripe rust is not easy to spread because overwintering bacteria can not infect smoothly.

? Fourth, prevention and control methods

Wheat stripe rust is an airborne disease, which can be prevented and controlled. If found in time, it can be controlled through scientific prevention and control. The prevention and control of wheat stripe rust should be "to find a point to prevent one, to find a piece to prevent one", to block the disease and prevent its spread. Triadimefon, tebuconazole, hexaconazole and propiconazole can be selected as control agents. In areas where wheat stripe rust has not been found, it is necessary to do a good job of "one spraying and three prevention" for wheat in an all-round way, and prevent wheat stripe rust while preventing wheat aphids and powdery mildew.