Field experiments were conducted to determine the effects of tank-mixing fluometuron {N,N-dimethyl-N′-[3-(trifluoromethyl)phenyl] urea} or MSMA (monosodium salt of methylarsonic acid) with sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} or the butyl ester of fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy] phenoxy] propanic acid} on cotton (Gossypium hirsutum L.) tolerance and large crabgrass [Digitaria sanguinalis (L.) Scop. # DIGSA] control. Postemergence (over-the-top) application of 1.7 kg ai/ha of fluometuron reduced cotton lint yield 17 to 23% in three of four tests. No yield reduction resulted from postemergence application of 1.1 kg ae/ha of MSMA. Tank-mixing 0.1 or 0.2 kg ai/ha of sethoxydim or 0.1 or 0.2 kg ae/ha of fluazifop with fluometuron or MSMA did not alter the effect of fluometuron or MSMA on cotton yield. Tank mixtures of 1.1 to 2.2 kg/ha of fluometuron plus sethoxydim or fluazifop were antagonistic. No antagonism was observed when fluometuron was applied 3 days before or 6 h following sethoxydim or fluazifop application. Tank-mixing 1.1 or 2.2 kg/ha of MSMA with sethoxydim or fluazifop initially reduced control of large crabgrass. Antagonism was not observed at 4 weeks after tank-mix application of MSMA plus sethoxydim, and was observed in only one of three experiments 4 weeks following tank-mix application of MSMA plus fluazifop. When antagonism was observed with tank mixtures of fluazifop plus MSMA, sequential application of MSMA 1 to 7 days before application of fluazifop did not overcome the antagonism. No antagonism occurred when MSMA was applied 6 or more hours after fluazifop application.

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.

Ethyl ester of DPX-Y6202 {2-[4-[(6-chloro-2-quinoxalinyl)oxy] phenoxy] propanoic acid} and butyl ester of fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} applied during the reproductive phase of development at 0.07 and 0.28 kg ai/ha prevented seed formation in downy brome (Bromus tectorum L. # BROTE). Fluazifop prevented seed formation over a wider range of application rates and growth stages than did DPX-Y6202. Seed production was prevented most readily by herbicide applications made early in the reproductive phase. Environmental factors during reproduction affected herbicide performance. Foliar absorption and translocation of 14C-fluazifop into the developing spikelets was greater than that of 14C-DPX-Y6202 in downy brome.

Lambert Erickson, retired professor from the University of Idaho Department of Agronomy, passed away July 7, 1986, in Moscow, Idaho. Dr. Erickson did his undergraduate work at the University of Minnesota. He earned a Master's degree in botany from the University of Wyoming in 1943 and a doctorate from the University of Minnesota in 1960. During his career, Dr. Erickson was active in professional and civic affairs. He was a member of the Weed Science Society of America; a Fellow of the Western Weed Science Society; and a member of the American Society of Agronomy, American Men of Science, and other professional groups. Dr. Erickson held Fulbright lectures on weed science in Europe in 1970 and was a Fulbright scholar to Norway in 1979. Dr. Erickson was a very active associate member of Farmhouse Fraternity. He was a long-time advisor and in 1978 was elected “Master Builder of Men.” He is survived by his wife Hazel and a son.

Soil factors that may affect activity of the propynyl ester of CGA-82725 {2-[(3,5-dichloro-2-pyridinyl) oxy] phenoxy] propanic acid}, methyl ester of haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, and butyl ester of fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} were examined. Adsorption of the three herbicides on three Illinois soils was similar but very low. Linear partion coefficients (Kd) ranged from 0 to 1.75 for CGA-82725 and haloxyfop, while no adsorption was detected for fluazifop on Drummer silty clay loam, Cisne silt loam, or Bloomfield sand. Conversion to the parent acid (active form) following application to the soil was rapid. The acid form was predominant for 2 months. Two metabolites were recovered; one was common to all three herbicides and intermediate in polarity to the acid and ester forms, and the other, unique to CGA-82725, was slightly more polar than the acid form. Extractability of the herbicides decreased dramatically over time. Haloxyfop and CGA-82725 leached to similar depths in soil column studies. Fluazifop tended to move more readily in the silty clay loam but less rapidly in the sand. Adsorption studies with 15 additional soil or sediment samples with widely varying physiochemical properties yielded adsorption (Kd) values of 0.79, 1.09, and 1.15 for fluazifop, haloxyfop, and CGA-82725, respectively, when averaged over all samples studied. Adsorption did not appear to be significantly influenced by organic carbon content, clay content, or pH.

Field and laboratory experiments were conducted in 1983 and 1984 to compare the degradation of dichlormid (2,2-dichloro-N,N-di-2-prophenylacetamide), dietholate (O,O-diethyl O-phenylphosphorothioate), EPTC (S-ethyl dipropyl carbamothioate), and butylate [S-ethyl bis(2-methylpropyl) carbamothioate] in soils that had or had not been previously treated with each chemical. EPTC + dichlormid, butylate + dichlormid, EPTC + dichlormid + dietholate, or butylate + dichlormid + dietholate were applied annually for 4 yr to field plots to establish treatment histories. Butylate and EPTC degradation was enhanced in soils with previous histories of butylate and EPTC, respectively. Degradation rates of dietholate were equivalent in untreated soils or soils previously treated with EPTC + dietholate or butylate + dietholate.

Field spectroradiometric plant canopy measurements showed that broom snakeweed [Gutierrezia sarothrae (Pursh.) Britt. and Rusby # GUESA] and spiny aster (Aster spinosus Benth. # ASTSN) had lower near-infrared (0.85-μm) reflectance than did other associated rangeland shrubs and herbaceous vegetation. The low near-infrared reflectances of both species were attributed to their erectophile (erect leaf/stem) canopy structures. These low near-infrared reflectance values caused broom snakeweed to have a dark-brown to black image on color-infrared aerial photos (0.50- to 0.90-μm), whereas spiny aster had a dark reddish-brown to black image. Other rangeland plant species had light-brown, red, or magenta images. Computer-based image analyses of color-infrared film positive transparencies showed that broom snakeweed and spiny aster infestations could be quantitatively differentiated from associated rangeland species. Computer analyses can permit “percent land area infested” estimates of broom snakeweed and spiny aster infestations on rangelands.