Pinoxaden performance as a function of water quality and storage time
摘要
The quality of water used to mix herbicide is critical for optimizing herbicide efficacy and crop yields. In this study we conducted field and pot experiments to examine the effects of key parameters related to water quality and herbicide mixture storage time on the performance of the herbicide pinoxaden for use against major grass weeds in wheat. It was hypothesized that the addition of ammonium sulphate would help overcome the effects of poor water quality (as measured by high levels of total dissolved solids – TDS) on herbicide efficacy. In field experiments we investigated the effect of water carrier hardness (42, 446, and 2200 ppm TDS) and addition of ammonium sulphate (0, 2.5, and 5 kg ha−1) on pinoxaden efficacy in control of weeds and yield of wheat (Triticum aestivum L.). In pot studies we evaluated the effect of water carrier pH (5, 7, and 9), and storage duration (application 0, 10, and 20-h after tank mixing) of pinoxaden on wild oats (Avena ludoviciana Durieu) and annual ryegrass (Lolium rigidum Gaud.) control. The highest level of water carrier hardness reduced weed control by pinoxaden by 34% and grain yield of wheat. The addition of the highest rate of ammonium sulphate increased pinoxaden weed control by 13.4% and the resulting wheat grain yield by 6.2%. Increasing water carrier pH from 5 to 9 and storage duration of the herbicide mixture up to 10 or 20 h both resulted in higher wild oats and annual ryegrass chlorophyll index, height and dry weight, and lower herbicide injury. Therefore, when faced with having to use hard water as a carrier for herbicide, farmers should consider the addition of ammonium sulphate to the herbicide mixture to increase pinoxaden performance. We also conclude that selection of a low pH water carrier and spraying immediately following tank mixing will help optimize pinoxaden performance by maximizing wild oats and annual ryegrass control.