Influence of temperature and relative humidity on the foliar activity of mesotrione

Abstract

Greenhouse studies were conducted to examine the influence of temperature and relative humidity (RH) on the foliar activity of mesotrione on five weed species. Regression analysis was performed allowing for comparison of estimated GR50 (herbicide dose to inhibit growth by 50%) values for each weed response at either temperature (18 or 32 C) or RH level (30 or 85%). Temperature and relative humidity did not influence the response of ivyleaf morningglory, common cocklebur, and velvetleaf to mesotrione markedly. An increase in temperature or relative humidity increased the efficacy of mesotrione on common cocklebur and velvetleaf up to threefold. Conversely, common waterhemp and large crabgrass were six- and sevenfold more susceptible at 18 C than at 32 C, respectively. Common waterhemp and large crabgrass were four- and twofold more susceptible to mesotrione at 85% compared with 30% RH, respectively. The influence of temperature and RH on the efficacy of mesotrione in foliar applications is species dependent and may be an important consideration for field applications.

Amino acid content and biomass productivity of selected weed species as an indicator of their response to herbicide stress

“…Moreover, this study showed greater biomass reduction under warm conditions for the mixtures 2.4-D+dicamba and 2.4-D+florasu-lam. These results are in agreement with the previous reports describing higher herbicide activity under high temperature conditions compared to low temperature [5,16,17]. In contrast to temperature, relative humidity did not influence weed response to herbicide stress.…”

“…It resulted in significantly smaller biomass reduction when both weed species were kept at low temperature in comparison with high temperature, while the mixture of 2.4-D with florasulam caused differences only when it was used against P. rhoeas. This agrees with the results obtained by C o e t z e r et al [4] as well as J o h n s o n and Y o u n g [16] who reported that particular weed species responded to herbicides applied under variable temperature regimes differently or some of them were not temperature dependent. Moreover, this study showed greater biomass reduction under warm conditions for the mixtures 2.4-D+dicamba and 2.4-D+florasu-lam.…”

Sistemas primários de transporte de prótons integram os mecanismos de desintoxicação do mesotrione em plantas de milho

“…As espécies de plantas suscetíveis ao mesotrione apresentam sintomas de amarelecimento nas folhas aos três dias após a aplicação (DAA), com posterior branqueamento, que progridem para a necrose e morte da planta em até duas semanas. Os sintomas se desenvolvem mais rapidamente na presença de luz (Pallet et al, 1998;Wichert et al, 1999;Johnson & Young, 2002) O mesotrione causa em algumas variedades ou híbrido de milho sintomas de fitointoxicação, porém isso não resulta em perdas na produtividade de grãos (Furtado, 2004;Masiunas et al, 2004). O milho é tolerante ao mesotrione, provavelmente, devido à capacidade de desativação do princípio ativo e à translocação para compartimentos celulares -vacúolo e meio extracelular (Mitchell et al, 2001;Johnson & Young, 2002;O´Sullivan et al, 2002).…”

Análise do perfil eletroforético de proteínas citoplasmáticas para verificação do processo de desintoxicação do herbicida mesotrione em plantas de Zea mays

“…As espécies de plantas suscetíveis ao mesotrione começam a apresentar sintomas de amarelecimento das folhas aos três dias após a aplicação (DAA), com posterior branqueamento das folhas, progredindo para a necrose e morte em até duas semanas (Pallet, 2000;Johnson & Young, 2002). Em alguns híbridos de milho mais sensíveis, o mesotrione tem provocado leve fitointoxicação, porém não foram observadas perdas na produtividade de grãos (O'Sullivan et al, 2002;Masiunas et al, 2004).…”