Evaluation of a seed-treatment method with acetone for delivering systemic nematicides with wheat and rye

Seeds of 'Coker 68-15' wheat and 'Maton' rye were immersed for 5 min in acetone solutions of oxamyl, carbofuran, or phenamiphos containing 0, 0.25, 0.5, 1.25, 2.5, or 5.0% (w/v) nematicide; after drying, seeds were planted in pots containing 500 gm of sandy loam naturally infested with Hoplolaimus galeatus and Tylenchorhynchus claytoni. In sterilized soil, only the 5% concentrations of all nematicides were toxic to rye, whereas both the 2.5 and 5% concentrations were damaging to wheat. Phenamiphos was generally the most phytotoxic compound. Numbers of T. claytoni in soil declined sharply in response to seed treatment with all nematicides. In soil planted with wheat, numbers were reduced 80% by the 1.25% treatment; little additional control was shown with higher concentrations. Soil with rye showed a 40-60% reduction in numbers of T. claytoni with the 1.25% solutions and little change at higher concentrations. Hoplolaimus galeatus developed only in pots with rye; root populations were suppressed (30-50%) by treatment with 1.25% or higher concentrations of all nematicides.