In 1982 and 1983, CGA 82725 {2-propynyl-2-[4-[(3,5-dichloro-2-pyridinyl)oxy] phenoxy] propanoic acid}, fenoxaprop {(±)-2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxyl]propanoic acid}, fluazifop {(±)-2-[4-[[5-trifluoromethyl)-2-pyridinyl] oxy]phenoxy] propanoic acid}, haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, and sethoxydim {2-[1-(ethoxyimino-(butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} were evaluated as postemergence treatments for the control of rhizome johnsongrass [Sorghum halepense (L.) Pers. # SORHA] in cotton (Gossypium hirsutum L. ‘Acala SJ-2′). Applications of fluazifop or haloxyfop, and the higher rates of sethoxydim or CGA 82725 or fenoxaprop, controlled 90% or more johnsongrass 20 and 52 weeks after application and prevented cotton yield losses.

Three adjuvants, ARD 54, ARD 93, and ARD 1836, were evaluated for their ability to reduce metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] phytotoxicity to soybeans [Glycine max (L.) Merr.] in sandy soils. A reduction in metribuzin phytotoxicity was observed, usually without reductions in sicklepod (Cassia obtusifolia L. # CASOB) control. The addition of linseed oil to a spray suspension containing 1% ARD 1836 reduced sicklepod control slightly at one of two locations. The addition of these adjuvants and linseed oil to the spray solution had no effect on soybean yield. These adjuvants slightly reduced movement of metribuzin in thin-layer soil chromatography but had no influence on sorption in batch-equilibrium experiments.

Huisache [Acacia farnesiana (L.) Willd. # ACAFA] and Mexican palo-verde (Parkinsonia aculeata L. # PAKAC) are native woody legumes that often occur together on rangelands of southern Texas and northern Mexico. Huisache produces a profusion of orange-yellow flowers during February or March giving it a conspicuous golden appearance. Mexican palo-verde produces a heavy bloom of yellow flowers in mid-April or early May giving it a yellow-green coloration. Plant canopy light reflectance measurements of flowering huisache showed that its reflectance at the 0.55- and 0.65-μm visible wavelengths was significantly higher than that of Mexican palo-verde in the vegetative stage and four other associated plant species or mixture of species. Conversely, reflectance measurements of flowering Mexican palo-verde showed that its reflectance at the 0.55-μm visible wavelength was significantly higher than that of huisache in the vegetative stage and the same four associated plant species or mixtures of species. Flowering huisache had a golden color on conventional color (0.40-to 0.70-μm) aerial photos that made it distinguishable from other plant species, whereas flowering Mexican palo-verde had a pink image on color-infrared (0.50- to 0.90-μm) aerial photos. However, immature plants of both species cannot be detected using this technique. Computer-based image analyses of conventional color film positive transparencies showed that huisache infestations could be quantified from associated rangeland species. This technique can permit ‘percent land area infested’ estimates of mature huisache on rangelands. These results show that aerial photography may be a useful tool to detect and monitor the spread of huisache and Mexican palo-verde on rangelands, and to delineate areas needing control.

Traditional weed control systems based on soil-applied herbicides and cultivations were compared with systems utilizing postemergence grass herbicides for Texas panicum (Panicum texanum Buckle. # PANTE) control in peanut (Arachis hypogaea L. ‘Florunner′) production. Maximum net returns ($150/ha) and peanut yield were achieved with traditional systems utilizing benefin [N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine] applied preplant incorporated plus alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] and dinoseb [2-(1-methylpropyl)-4,6-dinitrophenol] applied at ground cracking and two cultivations. The postemergence system using alachlor plus dinoseb applied at ground cracking and sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio) propyl]-3-hydroxy-2-cyclohexen-1-one} applied postemergence also provided maximum net returns ($146/ha) and peanut yield.

A new machine consisting of a detachable hopper of containerized granules with a preselected circular orifice to regulate flow of granules, and a revolving hollow-cone spreader turned by an electric motor, was tested. Flow of herbicide granules at typical use rates was linearly correlated with orifice diameter. Coefficients of determination for flow rates of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide], trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine], and norflurazon [4-chloro-5-(methylamino)-2-(3-(trifluoromethyl)phenyl)-3 (2H)-pyridazinone] were 0.96 or greater. Based on patterns of distribution of commercial trifluralin granules parallel and perpendicular to a linear path, the machine could be used to apply herbicide granules in row crops. Control of johnsongrass [Sorghum halepense (L.) Pers. # SORHA] with alachlor plus oryzalin [4-(dipropylamino)-3,5-dinitrobenzenesulfonamide] applied preemergence (pre) as sprays and granules did not differ significantly in soybean [Glycine max (L.) Merr. ‘Forrest′]. Trifluralin granules applied preplant incorporated (ppi) at 1.1 kg ai/ha controlled 80 to 95% of the johnsongrass and doubled soybean yield compared to the cultivated control plot. Norflurazon plus alachlor pre at 1.7 to 2.2 plus 2.2 to 3.0 kg ai/ha controlled annual grasses and prickly sida (Sida spinosa L. # SIDSP) equally with sprays and granules.

Herbicide solutions of known concentration were applied to honey mesquite (Prosopis glandulosa Torr. # PROJG) with a tractor-mounted carpeted roller. The volume of solution applied was measured, and average height and density of the honey mesquite stands were also determined. The volume of solution applied ranged from about 3 to 20 L/ha and was positively correlated with stand density (r2 = 0.71). Height of the stand had no influence on volume of solution applied. Amounts of herbicide applied at concentrations of 30, 60, and 120 g/L averaged about 0.2, 0.6, and 1.25 kg ae/ha, respectively. Calculated amounts of active ingredient of herbicide applied to individual plants (dosage) ranged from 0.3 to more than 3 g/shrub and decreased curvilinearly with increasing stand density, suggesting that the carpeted roller is most efficient in treating sparse stands.