Identification of dried tip of green onion and its control measures

Green onions are divided into physiological dry tip and pathological dry tip, and the latter "white dry" and "green dry" often make onion farmers confused, it is difficult to prescribe the right medicine, resulting in missing the best opportunity for prevention and treatment. Here, briefly talk about the causes and prevention measures of the two symptoms. White dry is caused by epidemic disease, which is easy to occur in the environment of high temperature and humidity, and the occurrence of rain on cloudy days is also the main reason for the dry tip of green onions. At the initial stage of the disease, the disease spot is dark green, water invasion, after expansion is gray-white disease spot, the periphery is not obvious, the leaves withered, when the disease is serious, the field is withered. Prevention and control agents can be selected, such as Pulek, Metalaxyl, mn-Zn and so on. However, it should be noted that because there is a layer of wax on the surface of onion leaves, attention should be paid to the addition of silicone auxiliaries when spraying to improve the adhesion of the agent. Green stem is harmful to Botrytis cinerea. The disease is serious under the condition of low temperature and high humidity at night, and now it has gradually become a secondary disease. In the initial stage of the disease, there are white spots on the leaves, nearly round or oval, 1-3 mm in diameter, developing from the leaf tip to the bottom, gradually connecting into flakes, so that the onion leaves curl and die. Prevention and control agents can be used to control hydantoin, Sukeling, nicotinamide and so on, and silicone additives should also be added to improve the control effect. In addition, the seed fly can also cause the green onion dry tip, the seed fly larvae eat into the green onion root harm, after pulling up the onion, the root turns brown, thus causing the aboveground leaf tip to dry up, and when the root is serious, the root rotates or dies. The cake out of the pot fell to the cinder at the touch of it.