抄録
The mobility of compounds in soil causes their loss due to leaching and/or run-off with moving water. Soil adsorption can reduce the mobility of isoprothiolane analogs in soils. Since the adsorption also lowers the concentration of analogs available to plants, there must be an optimal adsorptive character for the lasting effectiveness of pesticides. Affinity to plants increases the retention of the compounds but decreases their mobility in plants. The balance between retention and mobility in plants can determine compound distribution at the zone(s) where activity is required. Therefore, the affinity to plants is sometimes crucial for pesticides to exhibit their effectiveness. Both adsorption by soils and affinity to plants of isoprothiolane analogs well relate with the hydrophobicity, log P. Since obtained relationships between compound behavior and log P are nicely extendible to other types of compounds, the behavior can be generally predictable from the hydrophobicity of the molecule. Biodegradability in rice plants, rat liver homogenate or a fish-water system is also correlated with physicochemical property of the compounds. Factors influencing practical pesticidal activity may include intrinsic activity, compound behavior and biodegradability. These factors should be fully understood to optimize the practical effectiveness of pesticides. Like structure-activity relationship study for intrinsic activity, structure-behavior and structure-biodegradability relationships should be extensively studied for understanding the behavior and the biodegradability of pesticides.
