Degradation rates in soil of 1‐benzyltriazoies and two triazole fungicides

Abstract

AbstractThe degradation rates in soil of 1‐benzyltriazole together with six analogues having substituents in the phenyl ring and two commercial triazole fungicides, PP450 and triadimefon, were determined at 15°C and 20 % soil water content. The order of degradation rates of the benzyltriazoles was H > 4‐OCH3 > 4‐F>4‐Cl.4‐≥tert‐C4Hg3,4‐diCl>3‐CF3. Thus, in general, persistence was enhanced by electron‐withdrawing substituents and by lipophilic groups that increased sorption by soil.Of the commercial fungicides, PP450 was degraded very slowly (half‐life 578 days) while triadimefon was quickly converted (half‐life 15 days) to the corresponding alcohol, triadimenol, which in turn was degraded very slowly.The effects of temperature and soil water content on rate of degradation were studied for 1‐benzyltriazole and 1‐(4‐fluorobenzyl)triazole. The rate of degradation of 1‐benzyltriazole was more sensitive to soil temperature and water content than was that of 1 ‐(4‐fluorobenzyl)triazole. The influence of these results on the input data required by models which simulate persistence in field soil is discussed.