Control of Morningglories (Ipomoea spp.) in Sugarcane (Saccharum spp.)
Abstract Morningglories are summer annual or perennial dicots, and are troublesome weeds in sugarcane cultivated in northern India. If not controlled, they may compete with sugarcane, interfere in the harvest operation, and reduce yields. Managing morningglories in sugarcane continues to be a serious challenge for sugarcane growers. Field experiments were conducted during the 3-yr period from 2007 to 2009 to evaluate herbicides applied PRE and POST for control of morningglories in sugarcane. The herbicides applied PRE included diuron, metribuzin, and atrazine at 1.6, 1.4, and 1.0 kg ai ha−1, respectively, applied alone or followed by 2,4-D amine salt (0.58 or 1.16 kg ae ha−1) or 2,4-D sodium salt (0.8 or 1.6 kg ae ha−1) applied POST. Herbicides applied PRE controlled morningglories ≤ 87% at 15 d after treatment (DAT); however, control reduced to ≤ 56% at 90 DAT. Control improved when herbicides applied PRE were followed by POST application of 2,4-D amine or sodium salt. For example, diuron applied PRE followed by 2,4-D amine salt applied POST at any rate provided 100% control of morningglories at 15 and 30 DAT. At 90 d after POST application, control ranged from 68 to 82% with the PRE followed by POST herbicides, compared to 0% control when metribuzin or atrazine were applied PRE alone. The density and biomass of morningglories was also reduced to zero in treatments that included 2,4-D amine salt. The number of millable canes, cane height, and single cane weight was superior in PRE followed by POST herbicide treatments compared to herbicides applied PRE alone. Maximum cane yield was recorded for the treatments that included 2,4-D amine or sodium salt compared to only PRE treatments, and it was usually comparable with the nontreated weed-free control. It is concluded that a combination of PRE and POST herbicides were effective for control of morningglories; however, more research is required to evaluate other herbicides and their tank mix partners for control of morningglories in sugarcane. Nomenclature: Japanese morningglory, Ipomoea nil (L.) Roth.; obscure morningglory, Ipomoea obscura L. Ker Gawl.; sugarcane, Saccharum spp.
The effect of herbicide tank mix on the weed species diversity in sugarcane (Saccharum officinarum)
A field experiment was carried out at Triangle Estate, Zimbabwe to determine the efficacy of Pendimethalin, Chlorimuron ethyl and Metribuzin herbicide combinations on the weed species diversity in sugarcane. The experiment was laid out in a Complete Randomized Block Design (CRBD) with four replications. Treatments included; Chlorimuron ethyl (90g/ha), Metribuzin(2l/ha), Pendimethalin(2l/ha), Extreme Plus (0.8l/ha), Extreme Plus(1l/ha), Extreme Plus(0.8l/ha)+ Pendimethalin(2l/ha), Extreme Plus(1l/ha) + Pendimethalin(3l/ha), Pendimethalin(2l/ha) + Atrazine (2l/ha) and no weeding (control). The major weeds observed in this experiment are Amaranthus viridis, Ipomoea sinensis, Boerhavia erecta, Rotboellia conchinchinensis, Commelina bengalensis and Cyperus spp (purple and yellow). The herbicide tank mix of pendimethalin (2l/ha) + atrazine (2l/ha) significantly (p<0.05) controlled all weed species in this study except Ipomoea sinensis. The tank mix pendimethalin (2l/ha) + atrazine (2l/ha) resulted in 98.83% and 93% control for Amaranthus viridis and Rotboellia conchinchinensis respectively. Ipomoea sinensis was effectively reduced by metribuzin and Extreme plus (0.8l/ha) although its control was difficult. Extreme plus (0.8l/ha) effectively controlled all broadleaf weeds and Cyperus spp. Generally, spraying herbicides without mixing resulted in reduced control of weeds.
Efficiency of Chemical and Mechanical Methods for Controlling Weeds in Peanuts (Arachis hypogaea)
Research was conducted from 1978 through 1980 at Headland, AL, to evaluate the use of herbicides, mechanical cultivation, and hand-hoeing as components of a total weed control system for peanuts (Arachis hypogaea L.). Herbicides or two cultivations alone failed to provide acceptable weed control, peanut yields, or net returns for the 3-yr period. However, adding two cultivations to the herbicide treatments produced acceptable weed control, peanut yields, and net returns for the 3-yr period. Average peanut yield for herbicide(s) plus two cultivations was 3200 kg/ha with an average net return of $260/ha. Two cultivations plus two hoeings without herbicide(s) produced good results with an average 3-yr yield of 3380 kg/ha and a net return of $280/ha. Herbicide(s) plus two cultivation treatments that had net returns equal to two cultivations plus two hoeing treatments were: dinoseb (2-sec-butyl-4,6-dinitrophenol) at 5.0 kg ai/ha applied at ground-cracking ($300/ha); dinoseb + alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] at 1.7 + 3.4 kg ai/ha applied at ground-cracking ($310/ha); and alachlor at 4.5 kg/ha applied preemergence ($320/ha). Treatments containing herbicide(s) plus two cultivations plus two hoeings did not substantially improve weed control, peanut yields, or net returns over herbicide(s) plus two cultivations.