The use of chemical herbicides for weed control offers significant benefits such as saving labor, time, and delivering effective results, which has made them increasingly popular among farmers. However, these chemicals are a double-edged sword. While they can boost crop yields, improper use may lead to reduced production instead of improvement. With over 400 registered herbicide products in China and a relatively short history of use, many farmers lack the necessary knowledge and experience, leading to common issues like phytotoxicity. This is especially true during the rainy season, when weeds are rampant and herbicide application is frequent, increasing the risk of crop damage. Based on real-world scenarios, this article aims to provide a useful reminder to readers.
Phytotoxicity often occurs due to herbicide drift, particularly when non-target crops are affected by spray from herbicides. For example, 2,4-D butyl ester, widely used in wheat fields, is highly volatile and prone to drifting, causing harm to sensitive crops like cotton, beans, vegetables, and fruit trees. If sprayers are not properly cleaned after using herbicides and other pesticides are added without caution, phytotoxicity can still occur.
Some herbicides do not show immediate effects on the target crop but leave residues that harm future plantings. For instance, simazine used in corn fields can negatively affect rape, causing delayed germination and root rot. Similarly, applying herbicides to wheat straw might not cause harm, but planting peanuts afterward could result in root swelling and seedling death.
Improper application, such as incorrect dosage or timing, can also lead to crop damage. Overuse of herbicides in rice can cause weak plant structures, leaf spots, and stunted growth, severely affecting yield. Wheat, once in the jointing stage, becomes highly sensitive to certain herbicides, and misuse can lead to deformed ears.
To avoid phytotoxicity, it's essential to choose the right herbicide for each crop and growth stage. For example, butachlor is suitable for paddy fields, while acetochlor is better for dry land. Always check labels and follow instructions carefully. Avoid increasing dosage arbitrarily, as seen in many cases where farmers add more than recommended, leading to serious crop damage.
Prevent drift by spraying in calm weather, adjusting nozzle direction, and avoiding spraying upwind. 2,4-D butyl ester is especially harmful to dicotyledonous crops like cotton, soybeans, and vegetables. Farmers should be cautious when using it near these crops.
Herbicides with long residual effects must be considered when planning future crops. For example, atrazine used in corn fields can harm subsequent plantings like sugar beets or vegetables. Lastly, always clean sprayers thoroughly before switching between herbicides and other pesticides to prevent contamination.
By following these guidelines, farmers can reduce the risks associated with herbicide use and ensure safer, more effective weed management. (Jia Dengsan, Agricultural Bureau of Changle County, Shandong Province)
Farmers Daily
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