Increasing Importance and Control of Mayweed Chamomile in Forage Crops1

Abstract

AbstractMayweed chamomile (Anthemis cotula L.) is a cool‐season annual weed that germinates during March and matures by mid‐May in the southeastern United States. The economic importance of this weed in the pasture ecosystem has not been determined. The objectives of this study were: (i) to determine the forage quality of mayweed chamomile foliage; (ii) to survey the potential allelopathic influence of mayweed chamomile tissue extract on the development of certain forage species; and (iii) to evaluate herbicides for the control of this weed. The in vitro dry matter digestibility of mayweed chamomile ranged from 630 to 790 g kg−1, with the highest values residing in foliage harvested during the vegetative stage of plant development. Results of laboratory bioassays and growth chamber experiments indicated that water extracts of mayweed chamomile leaf material are potentially allelopathic to alfalfa (Medicago sativa L.) and Italian ryegrass (Lolium multiflorum Lam.) seedlings. Leaf tissue mixed in potting soil significantly reduced alfalfa and Italian ryegrass plant development. The extract and tissue concentrations used in this research were estimated to be similar to concentrations expected to occur within the pasture ecosystem. Paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) at 0.6 kg a.i. ha−1 and glyphosate [N‐(phosphonomethyl) glycine] at 1.2 and 2.4 kg a.i. ha−1 controlled mayweed chamomile in sericea lespedeza [Lespedeza cuneata (Dumont) G. Don] and bermudagrass [Cynodon dactylon (L.) Pers.] forage systems.