CONTROL OF NEALLEY'S SPRANGLETOP (LEPTOCHLOA NEALLEYI). E.A. Bergeron*, E.P. Webster, B.M. McKnight, J.C. Fish; LSU AgCenter, Baton Rouge, LA (70)
A study was established in a greenhouse on the Louisiana State University campus in Baton Rouge, Louisiana. The objectives were to evaluate herbicides for the control of Nealley’s sprangletop (Leptochloa nealleyi Vasey). The study was a completely randomized design with nine replications. The study was repeated. Nealley’s sprangletop seed was planted in plastic planting flats with 50 – 2.5 by 2.5 cm cells filled with potting mix until reaching one- to two-leaf growth stage. The Nealley’s sprangletop was transplanted into 6 by 10 cm cone containers filled with potting mix and placed into racks. The racks were placed in plastic containers and filled with 67 L of water for subsurface irrigation for the length of the study. Urea fertilizer, 46-0-0, was added to the water at 280 kg/ha.
Nealley’s sprangletop had one- to two-tillers with a height of 20- to 30-cm at herbicide application. Herbicides applied were: propanil at 2240 g ai/ha, propanil at 4480 g/ha, propanil plus thiobencarb at 3360 g ai/ha, propanil plus thiobencarb at 6720 g/ha, quinclorac at 420 g ai/ha, thiobencarb at 4480 g ai/ha, bispyribac at 28 g ai/ha, imazethapyr at 105 g ai/ha, imazomox at 44 g ai/ha, penoxulam at 40 g ai/ha, clethodim at 150 g ai/ha, cyhalofop at 314 g ai/ha, fenoxaprop at 122 g ai/ha, quizalofop at 185 g ai/ha, glufosinate at 450 g ai/ha, glyphosate at 840 g ai/ha. Nealley’s sprangletop control, leaf number, tiller number, and height were evaluated at 0, 5, 10, and 14 days after treatment (DAT). Fresh plant biomass was obtained at 14 DAT.
At 14 DAT, Nealley’s sprangletop treated with clethodim, fenoxaprop, and quizalofop was controlled 91 to 98%. Height and number of leaf and tillers were reduced with these herbicides compared with the nontreated. Nealley’s sprangletop treated with glyphosate and glufosinate, common burndown herbicides, controlled Nealley’s sprangletop 88 and 87%, respectively. Penoxulam and quinclorac had little to no activity on Nealley’s sprangletop. Fresh plant biomass of Nealley’s sprangletop treated with propanil or propanil plus thiobencarb at both rates, cyhalofop, fenoxaprop, clethodim, glyphosate, or glufosinate was less than 3 grams, compared with the nontreated with a fresh weight of 15 grams.
Nealley’s sprangletop is a prolific seed producer with high seed viability at maturity. It is important to correctly identify this weed in order to select the appropriate weed management program. Fenoxaprop is the best option for controlling Nealley’s sprangletop in rice production. Although not labeled in rice, Nealley’s sprangletop treated with clethodim and quizalofop was controlled 91 and 98%, respectively.