Growth of Potato and Control of Pratylenchus penetrans with Oxamyl-treated Seed Pieces in Greenhouse Studies.

Oxamyl was applied to both uncut and cut potato tubers in aqueous solutions of 1,000 to 32,000 mug/ml. Emergence in greenhouse pots was delayed for a day or more after soaking cut tuber pieces in 32,000 mug/ml. After 10 weeks plant growth was greater, relative to the control, when Pratylenchus penetrans-infested soil was planted with cut tubers soaked for 20 minutes in 32,000 mug/ml. Soaking for 40 minutes did not increase nematode control nor affect plant growth. Oxamyl applied to tubers at 1,000 mug/ml reduced the numbers of P. penetrans in the soil by 20% and in the roots by 35%; at 32,000 mug/ml, the numbers of P. penetrans in the soil were reduced by 73-86% and in the roots by 86-97%. The numbers of P. penetrans did not increase in the roots of plants developed from cut tubers soaked in 32,000 mug/ml over a period of 10 weeks, but numbers of lesion nematodes had begun to increase in the soil.