In recent years, the effectiveness of herbicides in corn fields has been disappointing, leading to criticism from some farmers. In response, the author conducted research and shared several key insights on this issue.
First, the root cause lies in the herbicide market itself. Due to intense competition, many manufacturers have resorted to price cuts and aggressive advertising campaigns. However, these strategies have led to increased production costs. To maintain profitability, some companies have reduced the concentration or quantity of active ingredients in their products. For example, previously, a 500-gram bottle of herbicide could treat three acres effectively. Now, most products come in 300-gram bottles with lower active ingredient content, covering only two acres—resulting in insufficient dosages and poor performance.
Second, climate conditions play a significant role. Three main issues arise: high temperature and drought during application. After sowing, if there is little rain, dry and hot weather can severely impact herbicide efficacy. Even with irrigation, the liquid evaporates quickly, reducing its effectiveness. A notable case was in 1998. On the other hand, excessive rainfall after application can wash away the protective layer of the herbicide, leading to loss of the chemical and ineffective weed control. Additionally, heavy rain later in the growing season can cause repeated weed emergence because soil-enclosed herbicides only last 45–60 days. This results in weeds appearing both early and late, as seen in 2003.
Third, improper application methods also contribute to the problem. Many fields have excessive crop residue, such as large amounts of wheat straw and stubble, which reduce the contact area between the herbicide and the soil. Some farmers use only 1–2 sprayers per acre, leading to uneven coverage and reduced effectiveness. Moreover, applying herbicides too late, when weeds are already well-established (like "grass-covered land" or "big grass full of lotus roots"), makes the treatment ineffective, especially for monocot weeds with more than three leaves.
Finally, the author suggests practical solutions. Instead of relying on advertisements, farmers should choose high-quality herbicides from reputable brands with high concentrations of active ingredients, such as 48% Zhongdian Caoba (CLP Group), 50% Xinyu Steam (Xuanhua), 48% Dingyi, or 42% cyantriazine. For fields with heavy crop residue, the "double increase one mix" method has proven effective. This involves increasing water usage (2–3 sprayers per mu) and boosting the dosage by 30–50% to counteract the interference from crop residue. The "one mix" part means combining two different herbicides with non-overlapping active ingredients, such as 48% Zhongdian Caoba + 40% Propyramid, or 50% Xinyu Steam + 42% Cyantriazine. Each herbicide should be used at 65–75% of the recommended dose to avoid phytotoxicity. For large weeds, applying 600–800 grams of glyphosate before spraying can help control them effectively. These strategies not only improve weed control but also ensure safer and more efficient herbicide use.
Hainan White Pepper
Hainan white pepper
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