Watermelon is cultivated in greenhouse, small arch shed and plastic film mulching. Because the temperature and humidity conditions in the protected area are suitable for the growth of weeds, the manual weeding operation is inconvenient, and the weeds grow vigorously and seriously. There are few registered herbicide products for watermelon fields in China, and many farmers use herbicides indiscriminately in watermelon fields, which leads to poor weeding effect and even phytotoxicity.

Herbicide in watermelon field

In addition to the registered herbicide varieties, such as butachlor, metolachlor, butachlor, quizalofop-ethyl and high-efficiency flupyrazole, other herbicides, such as butachlor of amide, oxyfluorfen of diphenyl ether, pendimethalin of dinitroaniline, glyphosate of cyclic imine, prometryne of triazole phenyl, thiacloprid of carbamate and flupyrazole of phenoxy, have been introduced. Butachlor is the first choice for weeding in most watermelon fields because of its relatively wide weeding spectrum, high safety and low use cost.

Causes of herbicide injury

First, improper product selection. Some herbicides registered for soybean, peanut, cotton and other crop fields are not suitable for watermelon fields, especially acetochlor, which is sensitive to watermelon. After application, the growth was inhibited and the seedlings died, resulting in serious yield reduction or even no harvest. Second, heat damage will aggravate drug damage. Watermelon in greenhouse and small arch shed is easy to cause heat damage due to sudden temperature rise and untimely film lifting. At this time, if the herbicide with strong volatility is selected, it is easy to cause high drug concentration in the air, causing serious phytotoxicity. Third, the drainage system in Gua Tian is very poor. There is a lot of rain in the growing period of watermelon. Under the condition of soil waterlogging, the activity of metolachlor and other drugs is greatly improved, and the safety is sharply reduced, which is easy to cause phytotoxicity. In addition, in sandy soil and soil with low organic matter content, some herbicides are easy to seep out under rain, which will cause phytotoxicity to watermelon.

Key points of herbicide application technology

Choose the herbicide registered on watermelon and use it in strict accordance with the instructions. At the same time, suitable chemicals should be selected according to different cultivation methods and weed population occurrence. Weeding in watermelon field mainly adopts soil sealing treatment, which is generally applied before sowing or transplanting. Herbs for controlling gramineous weeds, such as quizalofop-p-ethyl and high-efficiency flupyrazole, should be selected for stem and leaf treatment after seedling. In rainy areas or poorly drained fields, metolachlor and other drugs are advocated to be used in small quantities. Because of the high temperature in greenhouse and small arch shed watermelon field, the liquid medicine is volatile, so it is necessary to uncover the film in time and ventilate it in time to avoid the phytotoxicity caused by the high temperature in greenhouse, and the dosage should be based on the principle of ensuring safety. Plastic film watermelon is generally sprayed only on the part covered with plastic film, not on the whole field.