Herbicides Efficacy against Volunteer Oilseed Rape as Influenced by Spray Solution pH

Abstract

The pH of the spray liquid is one of the factors influencing the efficacy of herbicides. Adjusting the appropriate parameters of the spraying liquid may reduce the consumption of pesticides, which is in line with the currently introduced legal standards and society’s requirements. In the greenhouse experiment, the influence of herbicides containing mesotrione, nicosulfuron, rimsulfuron, bromoxynil, and a mixture of nicosulfuron, rimsulfuron, and mesotrione on the efficacy of oilseed rape control was investigated. Oilseed rape (Brassica napus L. ssp. oleifera), apart from being an important crop, can become a nuisance weed in many fields as form of volunteer plants. Visual assessment, reduction of fresh weight, and chlorophyll fluorescence were performed. Individual herbicides influenced the tested parameters to a different extent. The pH of the spray liquid influenced the efficacy of individual plant protection products. The highest herbicidal efficacy in relation to the tested plants was observed in the case of combinations in which mesotrione was applied at a reduced and increased pH, nicosulfuron applied in an acidic and alkaline environment, rimsulfuron without pH modification, and all treatments in which bromoxynil was applied. The herbicides containing mesotrione and bromoxynil had the greatest impact on the photosystem II activity.

Volunteer rapeseed infestation and management in corn

“…Similar findings have been reported by Grzanka et al. (2021), where 86% control and 84% biomass reduction in volunteer oilseed rape have been reported with the application of rimsulfuron at 15 g ai ha −1 . 2,4‐D resulted in 75% control 28 DAA and reduced volunteer rapeseed biomass by 73% (Table 5).…”

“…Grzanka et al. (2021) reported 83% visible control and 73% biomass reduction in volunteer oilseed rape ( Brassica napus L. ssp. oleifera ) with mesotrione at 100 g ai ha −1 .…”

“…Volunteer rapeseed biomass reduction was 71%, 58%, and 9% for mesotrione, tembotrione, and topramezone, respectively (Table 5). Grzanka et al (2021) reported 83% visible control and 73% biomass reduction in volunteer oilseed rape (Brassica napus L. ssp. oleifera) with mesotrione at 100 g ai ha −1 .…”

Spray water quality and herbicide performance: a review

“…Acidic or alkaline spray water pH can adversely affect herbicide efficacy by affecting the solubility, hydrolysis, dissociation, or chemical breakdown of the herbicide molecule (Green and Hale 2005;Roskamp and Johnson 2013;Sarmah and Sabadie 2002). A lower-or higher-than-optimal water pH may result in reduced solubility or rapid dissociation of active herbicide ingredient into an inactive degradative product, which subsequently affects the herbicide absorption and translocation (Green and Cahill 2003;Grzanka et al 2021;Roskamp et al 2013a).…”

“…For herbicides such as mesotrione, tembotrione, sulcotrione, and bipyrazone that inhibit 4-hydroxyphenylpyruvate dioxygenase (HPPD), improved efficacy has been reported with acidic or alkaline spray water pH; however, the response was variable with the weed species (Grzanka et al 2021;Sobiech et al 2018Sobiech et al , 2019Sobiech et al , 2020. The efficacy of mesotrione on horseweed increased with acidic compared to alkaline spray water .…”