Effect of Soil Moisture on Efficacy of Imazethapyr in Greenhouse¹

Abstract

A greenhouse study was conducted to evaluate the efficacy of imazethapyr at 35 and 53 g ai/ha applied preplant incorporated (PPI) or postemergence (POST) under various soil moisture regimes (13, 19, 25, and 50%) on barnyardgrass and red rice. Response of barnyardgrass and red rice to imazethapyr PPI was affected by soil moisture. With imazethapyr PPI, control of barnyardgrass was reduced at 50% soil moisture compared with other soil moisture regimes, and height of barnyardgrass increased as soil moisture increased from 19 to 50% 2 weeks after treatment (WAT). Barnyardgrass control declined and plant dry weight increased with the increase of soil moisture from 19 to 50% at 3 WAT. Imazethapyr PPI activity on red rice was reduced at 50% compared with other soil moisture regimes, as reflected by decreased control ratings as well as increased plant height and dry weight. Imazethapyr activity on barnyardgrass and red rice was increased at 50% soil moisture when applied POST compared with PPI. Imazethapyr POST activity on barnyardgrass and red rice was generally not affected by the soil moisture regimes or application rates. The results suggested that high soil moisture conditions reduced imazethapyr PPI efficacy on barnyardgrass and red rice. Imazethapyr POST activity seems unaffected by soil moisture conditions and thus may be used to control barnyardgrass and red rice if wet soil conditions are a concern.

Efficacy and selectivity of pre-emergent sunflower herbicides under different soil moisture conditions

“…Under dry conditions, the efficacy of PRE herbicides usually decreases (Zhang et al 2001;Zanatta et al 2008); however, intensive precipitation after application of these herbicides can cause crop injury (Stickler et al 1969;Soukup et al 2004). This effect is especially important for sunflower because the selectivity of most herbicides is dependent on the position of the herbicide layer on the soil surface and the distribution of seeds on the soil profile.…”

Comparação entre métodos químicos de controle de buva com início de dessecação em período seco ou úmido

“…Na literatura existem relatos que a condição hídrica do solo pode ou não influenciar o controle de plantas daninhas, como exposto por Zhang et al (2001) que o herbicida imazethapyr aplicado em pós-emergência de Oryza sativa não foi influenciado pela condição hídrica, entretanto Roman et al (2005) demonstraram que Euphorbia heterophylla submetidas a aplicação de carfentrazone-ethyl apresentaram melhores controles quando estavam sem déficit hídrico. Esse fato, provavelmente, se deve ao mecanismo de ação de cada herbicida citado.…”

The Potential Use of Oil Palm Frond Mulch Treated with Imazethapyr for Weed Control in Malaysian Coconut Plantation

“…Herbicide concentration in soil inversely related to the sum of soil moisture content and soil water partition coefficient (Green & Obien 1969). Zhang et al (2001) have demonstrated that higher soil moisture at 50% can reduce the efficacy of imazethapyr when applied as preplant treatment. In this study, the treatments were applied during rainy season.…”