Effect of weather conditions on efficacy of different herbicides used in Bromus sterilis control

Abstract

AbstractEfficacy of herbicides is strongly affected by weather conditions shortly before and after application. Small‐plot field trials were carried out in winter wheat in north‐west Bohemia, Czech Republic, Central Europe from 2011 to 2018. The relationship between meteorological characteristics and efficacy of acetolactate synthase inhibiting herbicides (mesosulfuron + iodosulfuron, propoxycarbazone and pyroxsulam) on Bromus sterilis was studied. The effects of precipitation before and after herbicide application, mean temperature and sunshine hours after the application were found to be statistically significant. The total precipitation 30 days before herbicide application had the greatest effect on herbicide efficacy. Mean efficacy significantly increased with increasing precipitation, when mean temperatures 5 days after treatment were above 9°C. The herbicide mesosulfuron + iodosulfuron was most affected by amount of precipitation while efficacy of pyroxsulam was minimally affected. When total rainfall amounted to 30 mm in the 20–40 days after herbicide application, there was no significant effect of total rainfall before herbicide application. In order to prepare the best weed control strategy against B. sterilis, weather conditions before and after the application term should be considered so that the growers can adjust for proper application timing and be prepared for a second application with a suitable herbicide.