Submitted to: Allelopathy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/16/2010
Publication Date: 3/15/2011
Publication URL: http://handle.nal.usda.gov/10113/60771
Citation: Hoagland, R.E., Mccallister, T.S., Boyette, C.D., Weaver, M.A., Beecham, R.V. 2011. Effects of Myrothecium verrucaria on morning-glory (Ipomoea) species. Allelopathy Journal. 27(2):151-162. Interpretive Summary: Morning-glories are very aggressive and hard to control weeds. During field testing of a bioherbicidal strain of the fungus Myrothecium verrucaria (MV), we discovered that certain volunteer morning-glory seedlings were injured or killed. Under controlled conditions, seedlings of seven morning-glory species were tested to determine the bioherbicidal effects of MV spores applied using a surfactant, or an invert emulsion. Ivyleaf, moonvine, and palmleaf morning-glories were the most tolerant to MV formulations, while pitted, multi-color, moonflower, and cypressvine morning-glories were highly sensitive. Formulations of MV combined with the invert emulsion generally increased injury and susceptibility. Results indicate differential bioherbicidal activity of MV among closely related species of morning-glories, and that the invert emulsion can increase the efficacy of MV in some instances.
Technical Abstract: During field testing of a bioherbicidal strain of the fungus Myrothecium verrucaria (MV) for control of spurges and purslanes in tomato plots in 2005, we noted extensive damage to volunteer morning-glory (Ipomoea spp.) seedlings. This observation prompted investigations on the biological control efficacy of this fungus on various Ipomoea species. Seven morning-glory species were grown in the greenhouse and tested in the first to second leaf growth stage. MV spores (107spores mL-1) were applied in Silwet L-77 surfactant or an invert emulsion. After application, the plants were placed in a dew chamber (15-18 h) and then transferred to a greenhouse. Injury caused by MV was assessed using a visual rating scale, and by fresh and dry weight determinations at termination of the tests. Ivyleaf (Ipomoea hederacea), moonvine (Ipomoea turbinate), and palmleaf (Ipomoea wrightii) morning-glories were relatively tolerant to MV, while pitted (Ipomoea lacunosa), multi-color (Ipomoea tricolor), moonflower (Ipomoea alba), and cypressvine (Ipomoea quamoclit) morning-glories were highly sensitive. Although some of these plants exhibited tolerance to spray applications of MV plus Silwet L-77, formulations of MV combined with the invert emulsion generally increased susceptibility. Results indicate differential bioherbicidal activity of MV among closely related species, i.e., Ipomoea (morning-glories), and that the invert emulsion can increase the efficacy of MV in some instances.