Precautions for selecting pesticides in high temperature season
It is hot and rainy in summer, which is the season of frequent pests and diseases , and it is also a peak period for pesticide use. How to choose pesticides after Futian? This article will introduce the selection method of pesticides after Futian, and I hope to help everyone.
First, the size of the spot disease is mainly harmful to the leaves, and sometimes infects the leaf sheath and the temporal lobe. In addition to the above-mentioned parts, the small spot disease can also damage the ear. The typical symptom of corn leaf spot is that it spreads rapidly from a small lesion to a long-horned large spot, which is as long as 10-30 cm. Sometimes several lesions are connected together to form irregular large spots. The lesions were initially immersed and quickly turned into a blue-gray color, which eventually turned into brown dead spots. When the air is humid, black molds can be grown on the lesions, that is, conidiophores and conidia of the bacteria. The onset condition of small spot disease is that the temperature is between 26 °C and 32 °C. Under high-humidity conditions, the low-lying land and the field density are too large to be closed. The pathogens are propagated on the foliage and re-infected by wind and rain. The suitable temperature of the large spot bacteria is 20 °C-28 °C, and the relative humidity of the air is more than 90%, which is beneficial to the propagation of pathogens. Temperatures above 25 ° C or below 15 ° C, relative humidity below 60%, the disease is inhibited. Maize jointing - the emergence of the rainy season is easy to catch.
Second, brown spot disease mainly occurs at the junction of the leaf base and the leaf sheath, and also damages the leaves, leaf sheaths and stems. The lesions are initially oily yellow-white round spots, which are later expanded into brown or purple, slightly bulging into a bubble-like circular plaque, the tissue around the lesion is red, and the lesions on the midrib or sheath are slightly larger. The large trumpet period is the susceptible stage of corn brown spot disease, which is common nowadays and there is a significant difference in the incidence between varieties. The suitable temperature for the onset of corn brown spot is 23 °C-30 °C. There are many rainy weather in the middle and late stages of corn growth, which is conducive to the epidemic under high humidity and high temperature.
The chemical control can be sprayed with 30% of water, 30% of rusting emulsifiable concentrate 3000 times or 12.5% ​​of diniconazole powder, and 30 kg of water.
Third, Curvularia leaf spot disease The disease is mainly harmful to the leaves, and sometimes also damage the leaf sheath, stalk leaves, the disease is a small nascent chlorotic spot, gradually expanding into a round to fade transparent spots, the middle is white to yellow brown, the edge is dark brown There are light yellow halos around, the symptoms vary greatly, and some only produce some white or brown dots. This disease is another serious disease after corn size spot disease. When the hot season in July-August, there are 4-5 days of rain, the disease may be popular.
For the control of the medicament, 50% of the antibacterial WP 1000 times or 12.5% ​​of the WPZ 4000 solution can be used, or 70% of the Mancozeb WP 1000 times can be used for the foliar spray at intervals of 7-10. For the second spray, it is advisable to spray 2-3 times.
4. Bacterial stem rot is mainly caused by sudden death of the plant in the middle of growth. It usually produces a yellow-brown to dark brown water-stained, inferior stagnation in the indirect part of the near surface, often with an unpleasant smell. The disease occurs during the small trumpet of the corn. The average temperature is 30 ° C, the relative humidity is above 70%, and the humid and hot weather is good for the disease.
The medicinal agent can be used with 85% trichloroisocyanuric acid 3000 times, and used once more every 7 days.
Matters needing attention: In the prevention and control of the disease should be considered. In the middle and late stages of maize growth, diseases and insect pests may be mixed on the same plant. When selecting drugs and applying drugs, one drug should be considered to be multi-effect, and one spray and multiple defenses should be considered. For example, spray insecticides with a broad spectrum of fungicides (such as diniconazole, carbendazim). In the disease control agent, foliar fertilizer such as Shibao, Ai Duo, or potassium dihydrogen phosphate can be added at the same time, which can promote the recovery of corn and improve disease resistance. Generally, the drug is administered once every 7 days or so, and the drug is administered 2-3 times.
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