COMPETITIVE EFFECTS OF BARNYARD GRASS AND CORN SPURRY ON YIELDS OF BIRDSFOOT TREFOIL

Abstract

The competitive effects of barnyard grass (Echinochloa crusgalli L.) and corn spurry (Spergula arvensis L.) on dry matter (DM) yields of Empire birdsfoot trefoil (Lotus corniculatus L.) harvested twice at the early bloom stage was investigated under greenhouse conditions. Yields obtained at the 1st cut were reduced significantly by barnyard grass and corn spurry. Barnyard grass was more effective than corn spurry in reducing yield, however, as the latter had little effect on yields of the legume when grown in association with barnyard grass. Results obtained at the 2nd cut indicated that only barnyard grass significantly reduced the yields of birdsfoot trefoil because of the good regrowth of barnyard grass and the severe reduction in the stand of corn spurry following the 1st cut. Field data obtained in a separate experiment were comparable to those from the greenhouse. Corn spurry and quack grass (Agropyron repens L.) greatly reduced yields of birdsfoot trefoil. The proportion of the total yield represented by birdsfoot trefoil was 20% and 80% in weedy and weeded plots, respectively. A test on the effects of barnyard grass and corn spurry on the frost resistance of birdsfoot trefoil has shown that the legume was more frost resistant when seeded alone. Results obtained in this study further illustrate the poor competitive ability of birdsfoot trefoil and the necessity of a weed control program during the seeding year.