Control of Pratylenchus penetrans and Meloidogyne hapla and Yield Response of Alfalfa Due to Oxamyl Seed Treatments.

Alfalfa (Medicago sativa L. cv. Saranac) seed were soaked for 20 minutes in water, acetone, or methanol containing 10 or 50 mg/ml of oxamyl (Vydate L) or coated with a 2% aqueous cellulose solution containing the same amounts of oxamyl. Seed were analyzed for oxamyl by HPLC immediately after treatment and after 9 and 26 months of storage. Oxamyl content of alfalfa seed did not decline after 26 months of storage. The effects of seed treatment on growth of alfalfa and nematode control were examined using soils infested with Pratylenchus penetrans and Meloidogyne hapla. Germination was not affected by any of the seed treatments. Twenty-one days after sowing, the total growth of alfalfa seedlings grown from seed treated with 50 mg/ml of oxamyl in P. penetrans-infested soils had increased by 62% over controls. Nodulation per pot increased by as much as 267%, and the densities of P. penetrans per gram of root were reduced by as much as 73% compared to control plants. In M. hapla-infested soils, increases in plant growth (32%) and nodulation (71%) also occurred with oxamyl-treated seeds. Root gall reduction (86%) was also substantial due to oxamyl seed treatment.