Efficacy of Multiple Applications of Oxemyl end Phenemiphos for Control of Pretylenchus penetrans in Birdsfoot Trefoil 1 L. S. THOMPSON and C. B. WILLIS

Prep lan t soil appl ica t ions of g r a n u l a r p h e n a m i p h o s effectively reduced Pratytenchus penetrans in soil d u r i n g the seeding year a nd 1 year after, and in the roots of birdsfoot trefoil 2 )'ears af ter seeding. Forage yields were increased in t he season fol lowing appl ica t ion of p h e n a m i p h o s , bu t s tands of p l a n t s / m s were not grea ter (P = 0.05) t han those in the checks 1 and 2 years after t rea tment . Addi t iona l spr ing appl ica t ions of p h e n a m i p h o s 1 and 2 years af ter seeding fu r the r reduced n u m b e r s of nematodes in the soil b u t did no t improve forage yields or p l a n t s t and over tha t of a single appl icat ion. Broadcast pt~eplant soil sprays of oxamyl followed by several foliar sprays at different rates and f requencies of appl ica t ion over a 3-year per iod restricted popu la t ions of P. penetrans in the soil a nd roots of b i rdsfoot trefoil bu t d id no t consistent ly resul t in increased forage yields. Stands of birdsfoot trefoil con t inued to decl ine each year even with oxamyl t rea tments .