Abstract
Sudden and unpredictable heavy rain showers are common in the wet tropical climate of Malaysia. Application of herbicides in Malaysia are at risk to washout by rain. based on rainfall data collected over the last 15 years, it is estimated that freshly applied herbicides are subjected to a 50 percent daily chance of washout by rain. Herbicide washouts result in economic losses for plantations, in terms of loss of labour, chemicals and bioefficacy. Several herbicides, including paraquat, glufosinate-ammonium, glyphosate and sulfosate [glyphosate-trimesium], were evaluated for rainfastness in tests with Ottochloa nodosa, Paspalum conjugatum and Imperata cylindrica. Paraquat was found to be rainfast in 15 minutes i.e. it will not be washed off plants even if rain falls as soon as 15 minutes after spraying. Glufosinate-ammonium and glyphosate were not rainfast and poor weed control was recorded even when rain fell 6 hours after spraying. In a separate experiment, sulfosate was found to be more rainfast than glyphosate.7 referencias.Sudden and unpredictable heavy rain showers are common in the wet tropical climate of Malaysia. Application of herbicides in Malaysia are at risk to washout by rain. based on rainfall data collected over the last 15 years, it is estimated that freshly applied herbicides are subjected to a 50 percent daily chance of washout by rain. Herbicide washouts result in economic losses for plantations, in terms of loss of labour, chemicals and bioefficacy. Several herbicides, including paraquat, glufosinate-ammonium, glyphosate and sulfosate [glyphosate-trimesium], were evaluated for rainfastness in tests with Ottochloa nodosa, Paspalum conjugatum and Imperata cylindrica. Paraquat was found to be rainfast in 15 minutes i.e. it will not be washed off plants even if rain falls as soon as 15 minutes after spraying. Glufosinate-ammonium and glyphosate were not rainfast and poor weed control was recorded even when rain fell 6 hours after spraying. In a separate experiment, sulfosate was found to be more rainfast than glyphosate.