Cotton and pitted morningglory emergence and dry weight decreased approximately 60 to 80% when these plants were grown under greenhouse conditions in the presence of increasing amounts (0.8 to 6.7 mg debris/g soil) of field-grown crimson clover or hairy vetch debris incorporated into the soil medium. Conversely, corn dry weight increased 20 to 75% when legume debris was placed on the soil surface; incorporated debris had very little effect on corn emergence or dry weight. Germination and seedling growth of corn, Italian ryegrass, cotton, pitted morningglory, and wild mustard decreased progressively, with species-dependent variation, when exposed to increasing concentrations (8.3 to 33.3 g debris/L) of aqueous crimson clover and hairy vetch extract. Mustard and ryegrass germination and growth were almost completely inhibited by full-strength extracts of both legumes. Bioassay species exhibited greater phytotoxic responses to hairy vetch than to crimson clover in the debris and extract studies. Emergence and growth of corn and cotton were not affected when planted into soil samples, containing root biomass and possible leaf and root exudates, collected from beneath field-grown hairy vetch and crimson clover plants. However, morningglory dry weight increased 35% in the presence of either legume root debris and accompanying soil.

Eight herbicide treatments per crop were evaluated for hairy vetch and crimson clover cover-crop control in no-till corn and cotton at two locations in North Carolina. Paraquat alone or combined with dicamba, 2,4-D, or cyanazine, and cyanazine alone, controlled clover the best in both crops. All herbicide treatments, except glyphosate alone, controlled at least 89% of hairy vetch in corn. However, only 2,4-D and cyanazine alone or combined with glyphosate controlled greater than 89% of hairy vetch in cotton. Except for poor control of hairy vetch and crimson clover by glyphosate alone, reduced legume control did not consistently decrease corn or cotton yield. Weed control was reduced in crimson clover treated with glyphosate alone, but control was similar among the remaining herbicide treatments. Effectiveness of legume control did not influence the N concentration of corn or cotton. Corn stand, height, and yield were greater in hairy vetch than in crimson clover. Seed cotton yield did not differ between vetch and clover.

No abstract

Laboratory studies were conducted to determine the effects of Acremonium endophytes on four species of billbug (Coleoptera:Curculionidae: Sphenophorus parvulus Gyllenhal, S. venatus (Say), S. inaequalis Say, and S. minimus Hart) found damaging cool-season turfgrasses in New Jersey. Billbug adults feeding on potted tall fescue (Festuca arundinacea Schreb.) plants infected with Acremonium coenophialum Morgan-Jones and Gams showed significantly greater mortality than billbugs feeding on endophyte-free tall fescue. Little difference was observed in amount of feeding. In petri dish preference tests, billbug adults were given a choice and, again, no significant difference was observed in the amount of feeding on endophyte-free versus endophyte-infected tall fescue tillers. In a third experiment, billbug adults were placed in petri dishes with either tall fescue with or without A. coenophialum or perennial ryegrass (Lolium perenne L.) with or without Acremonium lolii Latch, Christensen, and Samuels. Only small differences were seen in number of eggs laid and amount of feeding. Mortality of all four billbug species, however, was greater on both grasses when endophyte-infected.