Triallate Phytotoxicity and Nitrogen Fertilization

Application of NH4 +-bearing fertilizer in field and pot experiments increased triallate [S-(2,3,3-trichloroallyl)diisopropylthiocarbamate] activity on oats (Avena sativa ‘Harmon’). The effect was consistent in the growth chamber, but field results were more variable, depending on soil moisture and temperature conditions. Because the pot experiments showed that the major effect was in shoot-zone-treated soils, the increased triallate activity was attributed to a reduction in triallate adsorption to the soil colloids. However, a smaller effect was measured in root-zone-treated soil, thus a physiological effect is also possible.