Fall No‐Till Seeding of Alfalfa into Tall Fescue as Influenced by Time of Seeding and Grass and Insect Suppression1

Abstract

AbstractHigher nitrogen and pasture renovation costs have increased interest in no‐till seeding of legumes into grass pastures, but improved technology is needed for direct establishment of legumes in grass sods. This study was undertaken to quantify and evaluate the effects of seeding date, sward suppression, and insect pests on fall no‐till establishment of alfalfa (Medicago sativa L. cv. Arc) into tall fescue (Festuca arundinacea Schreb.)‐dominant swards. Six field experiments of 1 year duration each were conducted during a 5‐year period on either a Typic Hapludult or Ultic Hapludalf soil in the Piedmont of North Carolina. Paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium ion) for grass suppression and granular carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbarnate) for insect control either were not applied or were applied at 0.28 and 3.7 kg active ingredient (a.i.) ha−1, respectively, at two seeding dates (early September and mid‐October) in a 23 factorial combination. Three additional sodsuppression treatments (two trials) included (1) application of paraquat to 13 cm‐wide bands over 25.4‐cm rows at 0.28 kg a.i. ha−1, (2) broadcast application of glyphosate [N‐(phosphonomethyl) glycine] at 3.4 kg a.i. ha−1, and (3) post‐sowing clipping and removal of the fescue regrowth. Insects prevalent during establishment were identified and measurements were made of alfalfa stands, insect damage, winter survival, and dry matter production. Seasonal yields of September seeded alfalfa were increased 76 and 20% by sward and insect suppression during establishment, respectively (average six experiments). Insect damage was greater in early September plantings than in mid‐October plantings. Sward suppression and insect control interacted accumulatively under conditions of intensive insect feeding and moisture stress during establishment. Even though 50 to 100% of October‐seeded alfalfa in control plots had not advanced beyond the two‐trifoliolate‐leaf stage of development by early December, good winter survival occurred. We conclude that suppression of tall fescue was essential for best establishment and 1st‐year production of alfalfa and that insect control must be practiced in September no‐till plantings of alfalfa in some years.