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Lethal effect of atrazine and other triazine herbicides on ungerminated conidia of Cochliobolus sativus in soil

1989; Elsevier BV; Volume: 21; Issue: 6 Linguagem: Inglês

10.1016/0038-0717(89)90175-2

1879-3428

Thomas Isakeit, J LOCKWOOOD,

Plant and fungal interactions

The effect of atrazine and ten other triazine herbicides on conidia of Cochliobolus sativus exposed to fungistatic conditions in four soils was examined. Conidia borne on polycarbonate membranes were placed on the surface of soils (− 1 kPa matric potential) containing 25 μg g−1 herbicide and examined for germination on soil and for viability. Atrazine treatment caused germination and subsequent loss of viability of seven isolates of C. sativus on Boyer sandy loam (SL). However, it did not affect five other isolates of C. sativus, nor did it affect four isolates each of C. victoriae, C. heterostrophus or C. carbomun. Atrazine treatment also stimulated germination and resulted in a loss of viability of C. sativus in Capac loam and Colwood loam, but did not have these effects in Spinks SL. Moreover, the exposure of conidia of four isolates of C. sativus to 25 or 240 μg g−1 atrazine on Spinks SL increased their subsequent germinability on carbon-free salt solutions. Conidia did not germinate on nontreated soils, or lose any viability. Conidia which germinated on atrazine-treated soils lost viability within 3 days of germination on soil. Ametryn, cyanazine, prometon, simazine, prometryn, propazine and terbutryn, at 25 μg g−1 stimulated germination of two isolates of C. sativus on Boyer SL and decreased subsequent viability of their conidia, but not to the extent of 25 μg g−1 atrazine. Hexazinone, metribuzin and dipropetryn (25 μg g−1) did not stimulate germination of conidia on soil nor decrease their viability after 8 weeks.