Quinclorac is a hormonal herbicide and a selective herbicide for controlling rice stalks. Mainly by suppressing the growth point of valerian, the heart leaf can not be extracted to achieve the purpose of controlling valerian. The herbicide has been used for many years in the rice area of ​​Hunan Province, and its use has increased year by year. However, according to the investigation by the agricultural technology department, with the increase of resistance to the drug, some places increase the dosage arbitrarily, and the weather, temperature, seedling quality, improper use and other factors when using quinclorac are affected. It is sometimes reported when the drug is used everywhere. Therefore, we must conscientiously address the causes of phytotoxicity and find out the technical norms and measures to avoid disadvantages. We should not act recklessly, but should be "small."
According to the survey, rice fields produce phytotoxicity when using quinclorac, and the main reasons are as follows: 1 The application is early. As an acaricide, the drug is used differently in different cultivation methods of rice. Putian and live field must be used after the seedling 2 leaves and 1 heart. Transplanting rice and throwing japonica rice can be seen in the spraying of cockroaches. The best period of application is 2-3 leaf stage. Do not use this type of pesticide in rice farming. It is easy to cause flowering after use. In the production, some farmers can't catch the right time to use the medicine, resulting in phytotoxicity. For example, before the rice seedling 1 leaf stage, even when applied as a conventional dose, phytotoxicity is likely to occur. Some applied before 2 leaves and 1 heart period, 15 days after application, the leaves of the seedlings became darker, and the heart leaves began to curl from the sheath to form the onion tube leaves. The new leaves must break through the onion tube leaves to grow, and the new ones The leaves can not grow normally. Generally, the seedlings can be recovered after 2-3 leaves are grown. When the phytotoxicity is heavy, the new leaves cannot be born, causing death in Putian. Soaking seeds, exposed bud seeds, seedlings 2.5 before the leaf stage, rice tillering stage, and booting stage are sensitive to rice using quinclorac (salt), do not use. 2 The dosage is too large. Excessive use of drugs during the appropriate period of application, especially in the 4th leaf stage of rice seedlings, excessive drug use is prone to phytotoxicity. Generally, 50% quinclorac (salt) is used in live field and polder 30-40 per mu. Gram, this is the best medication period (valves 2.5-3 leaf stage), the amount of water should be 30-45 kg, not less than 30 kg. The recommended dosage of 36% dichlorobenzyl WP is 60 grams per mu. Due to the large age of grass in some fields, some farmers will increase the dosage per acre to 90-120 grams, which is easy to cause phytotoxicity to seedlings. The phytotoxicity is generally manifested 10-15 days after application, lasting 15-20 days, the symptoms are also forming onion tube leaves, but the leaf color is slightly lighter than the previous stage, and the new leaves are not easy to break through the onion tube leaves. It is worth noting that when used, the agent must be fully dissolved, and sufficient agitation should be done to prevent unevenness of the drug effect, and the spray should be uniform, so that it is not re-sprayed or leaked. 3 Different rice varieties have different sensitivities to quinclorac. Generally, conventional rice is more sensitive than hybrid rice, and the underdeveloped rice roots are more sensitive than the roots. 4 effects of weather conditions. For the safe use of quinclorac, it is necessary to master the actual seedlings and pay attention to the weather factors. The weak seedlings and the mulch-covered tender seedlings must be re-smelted due to poor resistance to harsh environments, so that the drug can be used after strong seedlings. When the temperature is lower than 20 °C, the growth of rice seedlings is slow, and the ability of rice to decompose quinclorac is poor, which increases the risk of using the agent. It is also easy to apply phytotoxicity to rice seedlings when applied under high temperature conditions. 5 Field management is not in place. Before weeding with quinclorac, it should be drained to a shallow water layer or moist soil. After 2-3 days, the water should be returned to the field and kept in a shallow water layer of 2-3 cm for 5-7 days, after which the normal field management is resumed. When farmers use this medicine, the field management sloppy, the depth of the water layer is more than 7 cm, and the water is deeply watered for a long time, or the water is too shallow before the medicine is used, which is more likely to cause phytotoxicity. 6 mist spray machine spray liquid concentration is too large. In order to ensure adequate dilution of the drug, spraying quinclorac is generally required to be sprayed with a hand sprayer, adding 30 kg per acre. If sprayed with a mist sprayer, the water consumption per mu is only 10-15 kg, and the concentration of the liquid is large. After 10 days of application, the seedlings will be dwarfed, stop growing, the leaves will become darker, and the onion leaves will appear in the field. If not remedied in time, the seedlings cannot be recovered in the short term.
The use of quinclorac to produce phytotoxicity is a relatively common problem. It must be taken seriously in production and every effort should be made to reduce the damage to rice. The main aspects: First, master the safe use of drugs at the appropriate time. In the rice field, the drug is generally used in the 2 leaf 1 heart period, and the drug is removed. In the direct seed rice field with a large gap between the ages, in order to prevent damage to the vulnerable seedlings, the drug should be postponed appropriately, and the 3-leaf stage should be appropriate. The delay in the use of the drug may lead to a large grass age, and the dose should be increased accordingly. If 36% dichloro-benzyl WP can be used, the dosage per acre is preferably 80-90 g, and it is controlled within 100 g. Daejeon medication is safer after the seedlings return to green and before the young ears are differentiated. Second, it cannot be mixed with a growth inhibitory regulator such as paclobutrazol or uniconazole or used in a short interval. Because the quincloracone-repressive selective herbicide has antagonistic effects with growth regulators such as paclobutrazol and uniconazole, it causes phytotoxicity. Therefore, it is necessary to use quinclorac at a 30-day interval for rice that has been used (or is ready to use) paclobutrazol or uniconazole. The third is to regulate the use of drugs. Put the field water before using the medicine, so that the whole plant of the weeds is treated with medicine. The water is not used within 24 hours after the medicine to ensure that the medicine is fully absorbed by the weeds. The fourth is the symptoms of rice phytotoxicity caused by various reasons, such as chlorosis at growth point, twisted heart, young leaves, longitudinal curl or onion tubular leaves, plant dwarfing, blackening of new leaves, causing plant growth to stagnate or gradually die It can spray humate foliar fertilizer , Bixin 0.136% 赤·å²ä¹™Â·Brassica WP, which is beneficial to alleviate the symptoms of phytotoxicity and is beneficial to the growth of rice roots. The symptoms are not relieved after the first application. You can spray again once a week. In some places, gibberellin is used to relieve the damage of quinclorac, but it is difficult to master when it is used in large areas. It may cause the rice plants that are not damaged or lightly damaged to grow normally, which is not conducive to management and reduce the loss of phytotoxicity.
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(Source: Agrochemical Investment Network)
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