bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the Efficiency of Sethoxydim in Flax
Authors: Friesen George H. , Wall David A.
Published: March 2018

The control of wild oat, volunteer wheat, and volunteer barley in a flax crop with sethoxydim was enhanced 20 to 27% by orienting the spray nozzles forward 45°. Control of annual grasses was not influenced by the time of day sethoxydim was applied. However, injury to flax from a tank mixture of sethoxydim and bromoxynil/MCPA (1:1) was greatest when applied between 0500 and 1100 h, and least when applied between 1500 and 2300 h. Flax injury and reduced seed yields also resulted when sethoxydim was applied when air temperatures exceeded 30 C regardless of stage of crop growth.
Diffusive Resistance and Transpiration of Quackgrass (Elytrigia repens) Following Postemergence Herbicides
Authors: Trimmer Mark C. , Linscott Dean L.
Published: March 2018

An established alfalfa stand infested with quackgrass received fluazifop-P, haloxyfop, or quizalofop at single applications of 0.28 ae kg ha-1and sequential applications of 0.14 plus 0.14 ae kg ha-1with the second treatment being made 16 d after the first. All herbicide treatments increased diffusive resistance and decreased transpiration of quackgrass compared to control plants. These effects became apparent 16 d or more after spraying. Visual injury symptoms were noted 8 to 10 d after treatment, several days prior to changes in diffusive resistance or transpiration. The alfalfa content of the first cutting was increased from herbicide treatment; however, total forage yield was reduced. Yields and composition of later cuttings were unaffected by the various herbicide treatments.
Growth and Development of Giant Burreed (Sparganium eurycarpum)
Authors: Leif John W. , Oelke Ervin A.
Published: March 2018

Outdoor experiments were conducted at two locations in Minnesota to characterize the growth, development, and vegetative reproduction potential of giant burreed grown with and without wild rice. Giant burreed growth was influenced by environment more than the presence of wild rice. Shoots emerged from corms 2 to 3 wk after planting (WAP), and continued throughout the growing season. Giant burreed attained a maximum height of 135 cm with an average 36 shoots/plant. Rhizome production started 4 to 6 WAP, and continued throughout the growing season. Corm formation at the base of shoots started 8 WAP and continued throughout the growing season. Rhizomes grew to a maximum cumulative length of 2500 cm/plant spreading in all directions and produced up to 250 buds/plant. Corm and rhizome bud viability was 15 and 10%, respectively. These data suggest that giant burreed grown in wild rice should be controlled by 2 to 3 wk after emergence to prevent vegetative reproduction.
Newly Seeded Alfalfa (Medicago sativa) Tolerates Glyphosate and SC-0224 at Doses That Control Dodder (Cuscutaspp.)
Authors: Dawson Jean H.
Published: March 2018

Newly seeded alfalfa tolerated glyphosate applied from the 8-trifoliolate leaf stage (17 cm tall) to the pre-bud stage (34 cm tall) at 75 or 150 g ae ha-1. Injury symptoms were moderate and temporary. Glyphosate at 300 g ha-1suppressed alfalfa severely and killed 30% of the plants when applied at the smallest (3-trifoliolate) stage of alfalfa growth. Alfalfa responded similarly to glyphosate and SC-0224.
Dodder (Cuscutaspp.) Control in Newly Seeded Alfalfa (Medicago sativa) with Glyphosate
Authors: Dawson Jean H.
Published: March 2018

A heavy, uncontrolled infestation of field dodder and largeseed dodder suppressed newly seeded alfalfa severely and killed many of the plants. Glyphosate at 75 or 150 g ae ha-1, sprayed over the top of the dodder-infested alfalfa, stopped the growth of dodder and did not injure alfalfa significantly. Treated dodder began to grow normally again 2 to 3 wk after treatment. This regrowth injured the alfalfa severely in spite of earlier control. Glyphosate at 75 or 150 g ha-1applied two or three times controlled dodder effectively and protected the alfalfa. A rate of 40 g ha-1was not effective.
Effects of Weed Control and Irrigation on the Growth of Young Pecans
Authors: Patterson Michael G. , Wehtje Glenn , Goff William D.
Published: March 2018

The effect of irrigation and weed control by various mechanical and chemical means was evaluated over a 4-yr period on newly planted pecans [Carya illinoensis(Wang.) K. Koch]. Weed control effect on tree growth became evident in the second growing season, and became more pronounced after the third and fourth season. After the fourth season, the maximum increase in tree diameter (384%) was achieved with comprehensive, herbicide-based weed control. Mowing provided a 224% increase, which was equivalent to the untreated (229%). Disking and selective chemical control of grass weeds resulted in 339 and 292% increase, respectively. Cumulative increase in tree diameter was 316 and 271% with and without irrigation, respectively.
Response of Bahiagrass (Paspalum notatum) to Plant Growth Regulators
Authors: Johnson B. Jack
Published: March 2018

Imazethapyr, glyphosate-isopropylamine salt, and glyphosate-sodium sesqui salt plus 2,4-D injured bahiagrass severely for 4 to 6 wk after treatment (WAT) but effectively controlled seedheads for 10 WAT without permanently reducing turf density. Imazethapyr applied twice at 0.08 kg ha-1suppressed vegetative growth of mowed bahiagrass by 5 WAT while unmowed turf was suppressed 62% by 6 WAT. Glyphosate-isopropylamine salt suppressed vegetative growth by 3 WAT, but did not consistently suppress unmowed bahiagrass. Bahiagrass treated with glyphosate-sodium sesqui salt injured bahiagrass more than glyphosate-isopropylamine salt when each was applied at the same rate. CGA 163935 suppressed bahiagrass seedheads for 8 WAT and vegetative growth from 2 to 4 WAT. The activity of mefluidide, MON 4620 plus paclobutrazol, paclobutrazol plus mefluidide, and flurprimidol plus mefluidide was minimal on bahiagrass.
ICIA-0051 for Postemergence Weed Control in Conventional Corn (Zea Mays)
Authors: Reddy Krishna N. , Bhowmik Prasanta C.
Published: March 2018

A 2-yr field study was conducted to evaluate the efficacy of ICIA-0051 for the control of annual grass and broadleaf weed species in conventional tillage corn. Treatments consisted of postemergence applications of ICIA-0051 alone and in combination with cyanazine or atrazine. ICIA-0051 at 0.6 kg ha-1 alone and in combination with cyanazine or atrazine at 1.1 kg ha-1 controlled large crabgrass, yellow foxtail, fall panicum, common lambsquarters, and redroot pigweed effectively (over 90%). The addition of cyanazine or atrazine at 1.1 kg ha-1 to the lowest rate (0.3 kg ha-1) of ICIA-0051 also improved large crabgrass, yellow foxtail, and fall panicum control by 9, 7, and 26%, respectively. None of the treatments of ICIA-0051 except the highest rate (1.1 kg ha-1) reduced either silage or grain yields of corn.
Effects of Tillage and Mulch on Weed Biomass and Sweet Corn Yield
Authors: Mohler Charles L.
Published: March 2018

Sweet corn was grown with a living mulch of white clover, a dead mulch of rye, and without mulch, in both till and no-till conditions. Unplanted controls were also included in the experimental design. Corn yields were highest in clover treatments early in the experiment but lowest in later years. The declining yields in the clover living mulch were related to the strip application of glyphosate which allowed establishment of perennial and biennial weeds, notably dandelion and horseweed. These overwintering weeds apparently prevented effective control of summer annuals, especially redroot pigweed, common lambsquarters and large crabgrass, by atrazine and metolachlor. Presence of a rye mulch decreased weed biomass and had no detrimental effect on corn yield. In general, corn yield was not affected by tillage, although the number of marketable ears was reduced in the no-till treatments during the drought year of 1988. The much greater weed biomass in the unplanted control treatments showed the importance of crop competition for weed control in sweet corn cropping systems.
Crambe (Crambe abyssinica) Tolerance to Herbicides
Authors: Stougaard Robert N. , Moomaw Russell S.
Published: March 2018

Crambe has gained interest as an alternative crop for industrial oil production. No herbicides are currently registered in crambe and weed control strategies need to be identified if crambe is to become a viable crop. Field experiments were conducted to determine crambe tolerance to several herbicides. Crambe was tolerant to soil-applied trifluralin, pendimethalin, and cinmethylin, or DPX-A7881 applied postemergence. Postemergence applications of chlorimuron or imazethapyr were injurious to crambe.
Soil Solarization Controls Broomrapes (Orobanchespp.) in Host Vegetable Crops in the Jordan Valley
Authors: Abu-Irmaileh B. E.
Published: March 2018

The effectiveness of soil solarization with black (BPE) and clear polyethylene mulches (CPE), 0.04 and 0.06 mm thick, respectively, was tested during the 1986 to 1990 growing seasons for controlling Egyptian broomrape, hemp broomrape and nodding broomrape in heavily infested fields. Solarization for 6 wk reduced or eliminated broomrape infestation and improved crop yields. The CPE started to show splitting and deterioration after 4 to 5 wk of solarization. The BPE lasted in usable conditions throughout the growing season. Deep soil tillage with the hand hoe, after solarization, caused broomrape to reappear. Crops grew best in plots after solarization with BPE if they were planted through the same mulch after it was perforated. Soil solarization with BPE or CPE in large tomato field trials, completely eliminated both nodding and hemp broomrapes during the growing season. However, greenhouse pot experiments indicated that solarization significantly reduced weed seedling numbers, but did not significantly reduce the dry weights of the broomrape plants that emerged in the soil samples taken from solarized plots.
Sequential Herbicide and Plant Growth Regulator Treatments on Bermudagrass (Cynodonspp.)
Authors: Johnson B. Jack , Murphy Tim R.
Published: March 2018

Sequential applications of MSMA plus metribuzin with selected plant growth regulators interacted synergistically and increased injury of ‘Tifway’ bermudagrass 1 and 2 wk after treatment. However, the higher injury at 3 wk after treatment, from sequential MSMA plus metribuzin with flurprimidol plus mefluidide or paclobutrazol with mefluidide, was additive. The vegetative growth suppression of bermudagrass at 2 wk after treatment with 2,4-D plus mecoprop plus dicamba with flurprimidol was antagonistic. The higher growth suppression 2 wk after treatment for MSMA plus metribuzin and flurprimidol plus mefluidide was additive compared to flurprimidol with mefluidide alone.
Weeds in Human Affairs in Sub-Saharan Africa: Implications for Sustainable Food Production
Authors: Akobundu I. Okezie
Published: March 2018

Sub-Saharan Africa (SSA) has the world's largest human population growth rate, some of its poorest soils, and a high incidence of crop pests. Weeds are the major pest in virtually all of the agro-ecological zones of SSA. Parasitic and perennial weeds dominate the savanna vegetation zones whereas rapidly growing annual weeds overwhelm crops in the forest vegetation zones. High weed pressure coupled with inefficient weed control practices have tied up a disproportionate percentage of SSA's economically active population in the primary task of food production and also have kept crop yields down. In the absence of organized weed research and professional training in weed science to meet the needs of the region, improved cultivars of virtually all crops fall prey to weeds, and available arable land becomes limited to that area that can be kept free of weeds. A preponderance of annual weeds in humid parts of SSA together with hard-to-kill perennial grasses and parasitic weeds in the subhumid and arid agro-ecological zones hamper crop production and frustrate farmers throughout the region. Sustainable food production in the region can be achieved by introducing improved weed management technologies and by addressing other food production constraints of the region.
Broadleaf Weed Control in Potatoes (Solanum tuberosum) with Postemergence Directed Herbicides
Authors: Eberlein Charlotte V. , Guttieri Mary J. , Fletcher Felix N.
Published: March 2018

Field studies were conducted to evaluate potato injury and weed control with postemergence-directed (PDIR) bromoxynil, glufosinate, or monocarbamide dihydrogen sulfate (MCDS). All three herbicides controlled hairy nightshade, common lambsquarters, redroot pigweed, and kochia ≥ 85%, depending on rate, with either mid- or late-PDIR treatment. Bromoxynil or MCDS caused 5 to 6% more initial injury with mid- than with late-PDIR treatment, but total yield and yield of U.S. #1 tubers were not reduced by either herbicide. PDIR glufosinate caused moderate injury at 0.84 kg ha−1, the rate needed for acceptable (≥ 85%) weed control. Total yield was reduced 10% and U.S. #1 yield was reduced 30% by PDIR glufosinate at 0.84 kg ha−1. Thus bromoxynil and MCDS showed potential for use as PDIR treatments in potatoes, but glufosinate did not.
Effects of Johnsongrass (Sorghum halepense), Hemp Sesbania (Sesbania exaltata), and Delayed Harvest on Soybeans
Authors: McWhorter Chester G. , Anderson James M.
Published: March 2018

The effect of delayed harvest was investigated with two soybean cultivars that were grown weed free or in competition with johnsongrass or hemp sesbania over a 3-yr period. Johnsongrass reduced the yield of early-maturing ‘Hill’ soybean 32, 35, and 36% when harvested at an average of 1, 2, or 3 wk after maturity, when compared to weed-free yields of 2490, 2430, and 2270 kg ha−1, respectively. Late-maturing ‘Lee 68’ yields were reduced 27, 29, and 39% on three harvest dates compared to weed-free yields of 2570, 2310, and 2200 kg ha−1, respectively. Seed grades of both cultivars improved with delayed harvest, but this was offset when johnsongrass was present. Hemp sesbania reduced yields of Hill 23% on the first harvest date and 26% on the second and third dates. Yields of Lee 68 were reduced 16, 22, and 28% by hemp sesbania on three successive harvest dates. The value of soybean yields adjusted for excessive foreign material, moisture, and damaged kernels was decreased by delayed harvest when hemp sesbania was present in Lee 68 and when johnsongrass was present in both cultivars.
Slender Speedwell (Veronica filiformis) Control in Cool-Season Turf with Quinclorac
Authors: Neal Joseph C. , Senesac Andrew F.
Published: March 2018

Experiments were conducted to compare rates and formulations of quinclorac for postemergent control of slender speedwell in cool-season turf. A 50% ae wettable powder formulation (50WP) was compared with two granular formulations, a 1% clay granule (1G) and a 0.4% corn cob granule (0.4G). Each formulation was applied at 0.3, 0.6, 0.8, and 1.1 kg ha−1. Additionally, 2,4-D at 1.1 kg ha−1 was applied alone and in combination with quinclorac 50WP at 0.8 kg ha−1. Slender speedwell control with the 50WP or 0.4G formulations was superior to that obtained with the 1G. At lower rates, slender speedwell control with the 50WP was greater than with the 0.4G; however, the rates required to obtain 95% control were not significantly different. Tank mixing quinclorac 50WP at 0.8 kg ha−1 with 2,4-D at 1.1 kg ha−1 did not improve slender speedwell control but increased roughstalk bluegrass injury. Kentucky bluegrass, perennial ryegrass, and tall fescue were not injured by quinclorac. Roughstalk bluegrass and chewings fescue were temporarily discolored. Turf injury was rate-related and more severe with the 50WP than the 1G formulation.
Effect of Soil Type and pH on Persistence and Carryover of Imidazolinone Herbicides
Authors: Loux Mark M. , Reese Kirk D.
Published: March 2018

Field studies were conducted in 1988 through 1990 to determine the effect of soil pH, over a 4.5 to 6.5 range, on imazethapyr persistence and on imazaquin and imazethapyr carryover to ‘Pioneer 3377’ corn in a Crosby silt loam (1.6% organic matter) and a Hoytville clay (3.3% organic matter). Imazethapyr appeared to be more persistent in Hoytville clay than in Crosby silt loam. In Crosby silt loam, imazethapyr persistence increased as pH decreased, whereas soil pH did not affect persistence in Hoytville clay. Imazaquin or imazethapyr did not affect corn grown the year following application to Crosby silt loam. Imazethapyr applied to Hoytville clay did not cause significant injury or yield reduction to corn. Carryover of imazaquin in Hoytville clay caused corn injury and yield reduction, increased as pH decreased, and was more evident at 280 g ai ha−1than at 140 g ha−1.
Selectivity Among Cabbage (Brassica oleraceaL.) Cultivars by Clomazone
Authors: Hopen Herbert J. , Hughes Robert L. , Michaelis Bruce A.
Published: March 2018

Excellent agreement between a two-year replicated study relative to chlorosis development by clomazone in thirty-six cabbage cultivars and development of chlorosis in a production field was obtained. The cultivars ‘Bravo’, ‘Cheers', and ‘Genesis' developed the most severe chlorosis symptoms and ‘Bently’, ‘Carlton’, ‘Cecile’, ‘Gourmet’, ‘King Cole’, ‘Ocala’, ‘Red Acre’, ‘Rio Verde’, ‘Roundup’, ‘Sombrero’, ‘Stonehead’, ‘Straton’, ‘Titanic’, and ‘Tristar’ the least chlorosis. During a dry soil period chlorosis symptoms were more pronounced. Yield reduction at an application rate exceeding the suggested use rate for weed control varied positively with level of chlorosis in 1992 for the cultivars Bravo, Cheers, Genesis, ‘Krautman’, and ‘Marvelon’.
The Effect of Giant Foxtail (Setaria faberi) Plant Height on Control with Six Postemergence Herbicides
Authors: Krausz Ronald F. , Kapusta George , Matthews Joseph L.
Published: March 2018

Field experiments were conducted from 1986 to 1988 to evaluate giant foxtail control at four plant heights by six POST grass herbicides. Clethodim, fenoxaprop, fluazifop-P, haloxyfop, quizalofop, and sethoxydim controlled 95% or more of 60-cm giant foxtail all three years at the labeled herbicide application rates. Control of 7-, 15-, and 30-cm giant foxtail with fenoxaprop, fluazifop-P, quizalofop, and sethoxydim was dependent upon soil moisture conditions at application. Clethodim and haloxyfop provided the greatest control (89 to 99%) regardless of plant height or soil moisture conditions. No herbicide injured soybean. Soybean seed yield with POST grass herbicides was equal to or greater than yield in the hand-weeded plots.
Rapid Diagnosis of Als/Ahas-Resistant Weeds
Authors: Gerwick B. Clifford , Mireles Linda C. , Eilers Robert J.
Published: March 2018

A method to rapidly identify acetolactate synthase/acetohydroxyacid synthase (ALS/AHAS)-resistant weeds is described based upon the differential accumulation of acetoin in the presence and absence of an ALS/AHAS inhibitor herbicide. Acetoin accumulation is induced by inhibition of ketol-acid reductoisomerase (KARI), the enzyme immediately following ALS/AHAS in the biosynthesis of branched-chain amino acids. Inhibition of ALS/AHAS prevents the build up of acetoin and forms the basis for distinguishing between sensitive and resistant biotypes. A new inhibitor of KARI, 1,1-cyclopropanedicarboxylic acid (CPCA), is described and was found to cause acetoin accumulation in velvetleaf leaf disks over the concentration range of 2 to 100 000μM. In the presence of CPCA, a number of species important to monitor for ALS/AHAS resistance were found to accumulate acetoin at rates sufficient for resistance diagnosis in 2 to 8 h. In velvetleaf, the youngest apical leaf was found to be the most active in acetoin accumulation. The resistance diagnosis method was validated by clearly distinguishing between imazaquin-sensitive and imazaquin-resistant cocklebur biotypes.
Sequential Herbicide Applications in Stale Seedbed Soybean (Glycine max)
Authors: Hydrick David E. , Shaw David R.
Published: March 2018

Field experiments were established in 1991 and 1992 on silty clay and sandy loam soils to evaluate various split rates of early PPI and PRE (to soybean) selective herbicides with and without paraquat for sicklepod and pitted morningglory control in stale seedbed soybean. Metribuzin at 360 g ai/ha plus 60 g ai/ha chlorimuron tank-mixed with 700 g ai/ha paraquat controlled sicklepod and pitted morningglory 83 and 91%, respectively, 4 wk after planting. Without paraquat, sicklepod and pitted morningglory control was only 65% and 67%, respectively. Imazaquin at 140 g/ha PRE tank-mixed with paraquat controlled sicklepod 78% and pitted morningglory 92%. Without paraquat, control was 38% and 84%, respectively. Early PPI applications of metribuzin plus chlorimuron or imazaquin at the full rate alone or followed by paraquat at planting resulted in poor control. With sequential treatments (PPI followed by PRE) the addition of paraquat at planting did not usually improve control, and either imazaquin or metribuzin plus chlorimuron provided equivalent control when compared with the full rate of either herbicide applied PRE. Season-long weed control was not obtained with any treatment in any experiment, and the crop was not harvestable.
Sulfonylurea Herbicides Suppress Downy Brome (Bromus tectorum) in Winter Wheat (Triticum aestivum)
Authors: Stahlman Phillip W. , El-Hamid Mosad Abd
Published: March 2018

In separate studies in west-central Kansas, a prepackaged mixture of chlorsulfuron + metsulfuron (5:1 w/w) and triasulfuron alone or in combination with metribuzin as a sequential or tank mix treatment were evaluated two years for downy brome control in winter wheat. Downy brome and wheat responses to each herbicide alone PRE or plus metribuzin POST varied between years. Visually, downy brome biomass was reduced 32 to 79% by chlorsulfuron + metsulfuron at 16 to 26 g ai/ha and 58 to 76% by triasulfuron at 30 g ai/ha applied PRE. Metribuzin POST at 158 g ai/ha following chlorsulfuron + metsulfuron PRE at 26 g/ha and metribuzin POST at 140 g/ha or more following triasulfuron PRE at 30 g/ha reduced downy brome biomass in both years more than PRE treatments alone. Chlorsulfuron + metsulfuron at 11 or 16 g/ha plus metribuzin at 105 or 158 g/ha applied POST affected downy brome less in 1992 than chlorsulfuron + metsulfuron applied PRE at 21 or 26 g/ha. Conversely in 1993, POST treatments except for chlorsulfuron + metsulfuron at 11 or 16 g/ha plus metribuzin at 105 g/ha affected downy brome more than PRE treatments. Triasulfuron plus metribuzin POST in late fall controlled downy brome better than a sequential application in one of two years; late-fall POST was better than early-spring POST applications in both years. Despite some treatments retarding growth, no treatment in either study reduced wheat yield in 1992. However in 1993, chlorsulfuron + metsulfuron PRE at 26 g/ha, chlorsulfuron + metsulfuron at 16 g/ha plus metribuzin at 105 or 158 g/ha applied POST, and metribuzin POST at 315 g/ha reduced wheat yields. Triasulfuron at 30 g/ha plus metribuzin at 140 g/ha or higher applied PRE, sequentially, or POST in late fall and metribuzin applied POST in early spring at 280 g/ha also reduced wheat yields.
Evaluation of Herbicides for Sweet White Lupin (Lupinus albus)
Authors: Ivany Jerry A. , McCully Kevin V.
Published: March 2018

The response of sweet white lupin to several herbicides was evaluated over five years at Charlottetown, Prince Edward Island (PEI) and two years at Cornhill, New Brunswick (NB). Excellent crop tolerance was found to the herbicides: chloramben, ethalfluralin, fluazifop-P, linuron, metobromuron, metolachlor, and trifluralin. None of the above herbicides affected crop grain yield or 1000 seed weight. Sweet white lupin was slightly injured by metribuzin at 500 g ai/ha but yields and 1000 seed weight were not affected. Higher rates of metribuzin reduced lupin yield and 1000 seed weight. Imazethapyr applied POST with 0.25% v/v Agral 90 and 1.0% v/v 28% N fertilizer caused severe crop injury and reduced lupin yields.
Herbicide Effects on Weed Control and Shoot Growth of Young Apple (Malus sylvestris) and Peach (Prunus persica) Trees
Authors: Foy Chester L. , Harrison Susan B. , Witt Harold L.
Published: March 2018

Field experiments were conducted at two locations in Virginia to evaluate the following herbicides: alachlor, diphenamid, diuron, metolachlor, napropamide, norflurazon, oryzalin, oxyfluorfen, paraquat, pendimethalin, and simazine. One experiment involved newly-transplanted apple trees; the others, three in apple and one in peach trees, involved one-year-old trees. Treatments were applied in the spring (mid-April to early-May). Control of annual weed species was excellent with several treatments. A broader spectrum of weeds was controlled in several instances when the preemergence herbicides were used in combinations. Perennial species, particularly broadleaf species and johnsongrass, were released when annual species were suppressed by the herbicides. A rye cover crop in nontreated plots suppressed the growth of weeds. New shoot growth of newly-transplanted apple trees was increased with 3 of 20 herbicide treatments and scion circumference was increased with 11 of 20 herbicide treatments compared to the nontreated control. Growth of one-year-old apple trees was not affected. Scion circumference of one-year-old peach trees was increased with 25 of 33 herbicide treatments.
Snap Bean (Phaseolus vulgaris) and Common Lambsquarters (Chenopodium album) Response to Acifluorfen
Authors: Wilson Henry P. , Hines Thomas E.
Published: March 2018

Field studies were conducted for 3 yr to determine the foliar activity of acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} for control of common lambsquarters (Chenopodium albumL. # CHEAL) in snap beans (Phaseolus vulgarisL. ‘Provider’ in 1983 and 1985 and ‘Green Crop’ in 1984). Control of 1 to 7 cm tall common lambsquarters varied between 75 and 100% with 0.28 kg ai/ha acifluorfen and frequently increased linearly with increases in acifluorfen rates to 0.84 kg/ha. Snap bean injury occurred each year and in 1985 was influenced by acifluorfen rate, stage of snap bean growth, and surfactant. Snap bean yields in 1983 were reduced linearly with increases in acifluorfen rates and in 1985 were reduced more from applications at the 1- to 2-trifoliolate leaf stage than at the 4- to 8-trifoliolate leaf stage. In the greenhouse, reductions in snap bean height from acifluorfen were related to application timing, surfactant and cultivar. Fresh weight reduction of snap beans was highest with the cultivar ‘Green Crop’ but was increased to both cultivars by early application timing and the addition of surfactant to the spray mix.
A Containment Facility for Research on Foreign Noxious Weeds
Authors: Creager Richard A.
Published: March 2018

Two conventional greenhouses were modified into a containment facility for the study of foreign noxious weed species that could be dangerous to North American agriculture. The facility was designed for research on the biology, ecology, and weed control technology of foreign noxious weeds, without the escape of propagules. Two growth chambers and a germinator are located within the containment facility for evaluations under controlled environmental conditions. A standard operating procedure is followed to preclude the escape of weed seeds or propagules while minimizing restrictions to research. The facilities are locked and located in a secure fenced area to reduce the probability of accidental or intentional damage. Procedures for emergencies have been designed to facilitate aid without compromising the containment security. Knowledge concerning weeds that have the potential to threaten North American agriculture will be gained from research performed within this facility.
Herbicide Action on Purple and Yellow Nutsedge (Cyperus rotundusandC. esculentus)
Authors: Pereira Welington , Crabtree Garvin , William Ray D.
Published: March 2018

Historically, many herbicides have been tested for control of purple and yellow nutsedge, (Cyperus rotundusL. # CYPRO and (C. esculentusL. # CYPES). However, most chemicals provide only poor or temporary control. Reasons for failure include marginal translocation of herbicides to sites of action, temporary inhibition of tuber sprouting, and control of new tuber formation or inconsistent control when applied at different stages of growth and under various environmental conditions. Evaluation criteria that emphasize control of new plants and foliage rather than inhibition of tuber sprouting or new tuber production also contribute to erratic results. Progress toward solving these research problems is evident in studies of the influence of herbicides relative to nutsedge growth stages, new tuber development, and tuber recovery following treatment. In this review, nutsedge response to herbicides grouped by their mode of action within plants will be summarized.
Year-Round Management of Yellow Nutsedge (Cyperus esculentus): An Extension Worker's Summary
Authors: William Ray D. , Bendixen Leo E.
Published: March 2018

Extension workers often identify production, marketing, managerial, or educational constraints that reduce agricultural efficiencies. The preceding papers documented that both yellow and purple nutsedge (Cyperus esculentus L. # CYPES and C. rotundus L. # CYPRO) are serious weeds in many worldwide agricultural cropping systems. Detailed literature reviews and suggested directions for future research also were presented. As a partial summary of the symposium, this paper attempts to condense the information regarding yellow nutsedge into several options or strategies for consideration by year-round weed management practitioners.
Colonel Johnson's Grass: Johnsongrass
Authors: Mitich Larry W.
Published: March 2018

Johnsongrass [Sorghum halepense (L.) Pers. # SORHA], native to the Mediterranean region, is one of the worst weeds ever introduced into the United States. While the precise date of its introduction is unknown, johnsongrass probably was present early in the 19th century. Before 1874, johnsongrass, described under eight botanical names and identified by over 40 common names in the literature, was most commonly called guinea grass and Means grass.
Herbicidal Control of Velvet Lupine (Lupinus leucophyllus)
Authors: Ralphs Michael H. , Williams M. Coburn , Turner David L.
Published: March 2018

Several herbicides were evaluated for the control of velvet lupine (Lupinus leucophyllus Dougl. #3 LUPLE), a plant poisonous to sheep on western mountain ranges, and a secondary target species, mountain big sagebrush [Artemisia tridentata Nutt. # ARTTR]. Change in foliar cover of the two target species and associated vegetation was used to evaluate efficacy of the herbicides. Velvet lupine cover was reduced by greater than 50% in the 1983 trial by the butyl ester of 2,4-D [(2,4-dichlorophenoxy)acetic acid] at 2.2 and 4.5 kg ae/ha, the butoxyethanol ester of 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] at 1.1 and 2.2 kg ae/ha, the dimethylamine salt of dicamba (3,6-dichloro-2-methoxybenzoic acid) at 2.2 kg ae/ha, and 2,4-D plus dicamba at 1.1 plus 0.6 kg/ha. Cover of velvet lupine and other forbs was reduced by drought in the spring of 1985 and obscured the comparison among herbicides in the 1984 trial. Cover of mountain big sagebrush was consistently reduced (>88%) by 2,4-D at 4.5 kg/ha in both trials, and by three rates of the butoxyethyl ester of triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} (>67%) in the 1984 trial. Grass cover increased in plots where herbicides effectively reduced velvet lupine, forbs, and mountain big sagebrush.
Propagules of Purple Nutsedge (Cyperus rotundus) in Soil
Authors: Siriwardana Gamini , Nishimoto Roy K.
Published: March 2018

The upper 30 cm of soil in a field infested with purple nutsedge (Cyperus rotundusL. #3CYPRO) contained 4900 to 5100 corms and tubers/m26 weeks after soil rotovation and irrigation. The upper 4, 8, 12 and 16 cm of soil had 45, 79, 95 and 99%, respectively, of the corms and tubers. Lower depths of soil contained larger tubers with higher percent dry matter than the shallow depths. Of the total number of corms and tubers, 51% were from the parent population. At 6 weeks, only 15% of the total tuber and corm population were not connected to aerial parts. Tubers from the parent population had a higher fresh weight than those from the new population. Parent tubers occurred singly or in chains of up to eight tubers.
Broadleaf Weed Control in Safflower (Carthamus tinctorius) with Sulfonylurea Herbicides
Authors: Anderson Randy L.
Published: March 2018

Safflower (Carthamus tinctorius L. ‘Hartman’) in the rosette growth stage or early bolting stage tolerated thiameturon {3-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] amino] sulfonyl]-2-thiophenecarboxylic acid} at 5, 10, and 15 g ai/ha. Safflower also tolerated chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} at 18 g/ha if safflower was taller than 15 cm at time of application. The fresh weight of above-ground biomass of common sunflower (Helianthus annuus L. #3 HELAN), treated at two plant sizes with thiameturon, was reduced more than 88%. Soil activity of thiameturon also reduced the seedling vigor of common sunflower, but thiameturon in soil was not as lethal to common sunflower as were foliar applications.
The Development and Future Trend of Weed Science in Mainland China
Authors: Li Yang-Han
Published: March 2018

Professor Li has taught botany since 1940 at University of Nanking, Nanking, China, and weed science at Nanjing Agricultural University, Nanjing, China, since 1964. He developed and taught the school's first weed science course and he presently teaches botany, crop plant anatomy, and weed identification and control. Under his direction, programs in weed quarantine and biological weed control have been instituted and supported by the Ministry of Agriculture and the Bureau of Education (present name: Ministry of Agriculture, Animal Husbandry and Fishery). One of his prime targets has been the study of darnel and the biological control of dodder on soybeans. Professor Li is the supervisor of several graduate students for the Masters and Ph.D. degrees. While at Nanjing, he also has directed the establishment of the most complete herbarium of weeds and weed seeds in China. Currently, Professor Li is editing Weed Flora of China. In addition to publishing many weed texts and teaching short courses on weed identification and control within China, he is a member of the FAO Panel of Experts on Improved Weed Management.
Tomato (Lycopersicon esculentum) and Eastern Black Nightshade (Solanum ptycanthum) Tolerance to Aciflurofen
Authors: Gorski Stanley F. , Wertz Monica K.
Published: March 2018

Field experiments were conducted to determine the influence of growth stage on tolerance of seeded tomatoes (Lycopersicon esculentumMill.) and of eastern black nightshade (Solanum ptycanthumDun. #3SOLPT) to the sodium salt of acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} at low use rates. Tomatoes as young as the 2 true-leaf stage exhibited some tolerance to acifluorfen at rates of 0.14 kg ae/ha and less. Rates of 0.28 and 0.56 kg/ha caused increased phytotoxicity; however, yield was not greatly reduced. At the 8-leaf stage, foliar injury was slight and existed only at the highest rates tested; however, tomato yields were reduced. Control of black nightshade at the 2-leaf stage was acceptable at rates as low as 0.14 kg/ha. When nightshade was at the 5-leaf stage, 0.28 and 0.56 kg/ha rates provided acceptable control − 87% and 96%, respectively. Nightshade in the 10-leaf stage was not controlled effectively at rates below 0.56 kg/ha.
Flax Response to Trifluralin
Authors: Nalewaja John D. , Kolota Eugeniusz , Miller Stephen D.
Published: March 2018

Experiments were conducted in the greenhouse and in the field to determine the influence of flax (Linum usitatissimumL.) seeding depth on tolerance to trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine]. Flax stand and fresh weight generally decreased as flax seeding depth increased within or below trifluralin-treated soil. Seeding flax below a trifluralin-treated soil layer did not increase tolerance to trifluralin. Although 0.8 kg ai/ha of trifluralin reduced stand when flax was seeded 3 to 6 cm deep in the field, seed yield remained constant.
Herbicide Combinations in Peanut (Arachis hypogaea)
Authors: Grichar W. James , Boswell Thurman E.
Published: March 2018

When tank mixed with certain boadleaf-selective herbicides, fluazifop {(+)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, and fluazifop-P {(R)-2-[4-[[5-trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} were less effective in controlling two annual grasses, Texas panicum (Panicum texanumBuckl. #3PANTE) and large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA]. These herbicides were applied alone or were combined with the broadleaf-selective herbicides bentazon {3-(1-methylethyl)-(1H)-2,l,3-benzothiadiazin-4(3H)-one-2,2-dioxide} and/or 2,4-DB [4-(2,4-dichlorophenoxy)butanoic acid]. The herbicide combinations controlled smooth pigweed (Amaranthus hybridusL. # AMACH) and yellow nutsedge (Cyperus esculentusL. #CYPES). Increasing the rates of the grass-selective herbicides in the mixture reduced the adverse effects of 2,4-DB or bentazon.
Energy Requirements and the Effect of Rotary Tiller Configurations On Cyanazine Distribution on Ridges
Authors: Wilson Robert G. , Smith John A.
Published: March 2018

Experiments were conducted to determine the energy requirements and the most effective rotary tiller configuration for incorporating cyanazine {2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl] amino]-2-methylpropanenitrile} on an 18-cm band centered on top of the previous year's corn (Zea maysL.) ridge. When the rotary tiller was operated full width at a 10-cm depth, the least cyanazine concentration was found in the center of the ridge, and the greatest concentration was found between ridges. The treatment having the greatest cyanazine concentrations in the center of the ridge and the least in the inter-row between ridges consisted of a ridge cleaner, a cyanazine application, and the rotary tiller configured to till a. 30-cm strip on the center of the ridge with a rotor enclosure. Energy requirements for operating the rotary tiller increased as the depth of operation increased, and the 10-cm depth of operation required less energy than two passes with a tandem disk.
The Compatibility of Rhodamine B Dye with Herbicides for Common Crupina (Crupina vulgaris) Control
Authors: Zamora David L. , Thill Donald C.
Published: March 2018

The compatibility of rhodamine B dye {N-[9-(2-carboxyphenyl)-6-(diethylamino)-3H-xanthen-3-ylidene]-N-ethyl ethanaminium chloride} with picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) or dicamba (3,6-dichloro-2-methoxybenzoic acid) was evaluated in the laboratory and field. Rhodamine B dye formulation (with or without a surfactant) did not affect dry weight of residue precipitated when mixed with dicamba. Formulated dye precipitated 11% more residue than nonformulated dye when mixed with picloram. Common crupina (Crupina vulgaris Cass. # CJNVU) field plant density was higher after applying a picloram spray solution with nonformulated rhodamine B dye compared to picloram alone. Common crupina density and biomass were higher after application with nonformulated dye and dicamba compared to dicamba alone.
Cyanazine Residues on Fieldbeans (Phaseolus vulgaris) as a Replant Crop
Authors: Wilson Robert G.
Published: March 2018

Field research was conducted in 1983 and 1984 at Scottsbluff, NE, to determine the effect of cyanazine {2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methyl-propanenitrile} applied in corn (Zea maysL. ‘Pioneer 3732’) on fieldbeans (Phaseolus vulgarisL. ‘Valley’) planted 30 days later to replace corn. Cyanazine preplant incorporated at 1.1 kg ai/ha or higher reduced the vigor, stand, and yield of fieldbeans as a replant crop.
Influence of Nitrogen on the Response of ‘Tifway’ Bermudagrass (Cynodon dactylon) to Flurprimidol
Authors: Johnson Billy J.
Published: March 2018

Vegetative growth of ‘Tifway’ African bermudagrass (Cynodon transvaalensisBurtt-Davy # CYNTR) x bermudagrass [C. dactylon(L.) Pers. # CYNDA] treated with flurprimidol {α-(1-methylethyl)-α-[4-trifluoromethoxy)phenyl]-5-pyrimidinemethanol} at 0.2 kg/ha and repeated at 3-week intervals for a total rate of 0.8 kg/ha was suppressed for 6 weeks compared to growth of nontreated grass. A single application of flurprimidol at 0.8 kg/ha in late May suppressed growth for 4 weeks. When the single 0.8 kg/ha application was delayed until mid-July, bermudagrass growth was suppressed for only 2 weeks. Applications of nitrogen (N) at 25 and 50 kg/ha did not influence flurprimidol's suppression of bermudagrass growth. Turf quality in some instances was lower when treated with 50 kg N/ha or the turfgrass required a longer recovery period than when treated with 25 kg N/ha following flurprimidol treatment. Although single or multiple applications of flurprimidol, each totaling 0.8 kg/ha, injured bermudagrass in some instances, the injury was not severe and the turfgrass fully recovered.
Crabgrass
Authors: Mitich Larry W.
Published: March 2018

Crabgrasses (Digitaria spp.), the first cultivated grains, were grown for food thousands of years before they were considered weeds. Digitaria, a genus of about 60 species, grows in the world's temperate and tropical regions. Many of the species are good forage grasses. Thirteen weedy Digitaria species infest the United States, but large crabgrass (D. sanguinalis # DIGSA) and smooth crabgrass (D. ischaemum # DIGIS) are the most common.
Leaf Area and Competition for Light between Plant Species using Direct Sunlight Transmission
Authors: Walker Graham K. , Blackshaw Robert E. , Dekker Jack
Published: March 2018

A technique based on the relationship between leaf area index (LAI) and the transmittance of direct sunlight was developed for thein situstudy of competition for light between plant species. Field studies were conducted in 1984 and 1985 using monocultures and mixtures of rapeseed (Brassica napusL.), wild mustard (Sinapis arvensisL. # SINAR), and common lambsquarters (Chenopodium albumL. # CHEAL). LAI estimated nondestructively by this method agreed closely with LAI determined by conventional destructive techniques. Light measurements at several heights in the canopy were used to determine the vertical distribution of canopy leaf area. Combining this information with species heights allowed the separation of the canopy LAI into individual species LAI, from which light competition could be estimated by calculating the sunlit LAI of each species. The technique permits many detailed measurements in the same canopy throughout the growing season. The light sensor required is not costly and is simple to operate and to maintain.
Effect of Rate and Carrier on Clomazone Movement Off-site
Authors: Halstead Sandra J. , Harvey R. Gordon
Published: March 2018

Field studies were conducted in 1985 and 1986 to determine the influence of herbicide rate, carrier, and carrier volume on off-site movement of clomazone {2-[2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxalidinone} using sunflower (Helianthus annuusL. ‘HY-894’) and wheat (Triticum aestivumL. ‘Caldwell’) as indicator plants. Clomazone applied at the lowest rate (0.56 kg ai/ha) had less off-site movement than higher rates. Off-site movement was similar among water carrier volumes applied at each clomazone rate but was less when clomazone was impregnated onto dry fertilizer.
Selective Application of Herbicides for Canada Thistle (Cirsium arvense) Control in Birdsfoot Trefoil (Lotus corniculatus)
Authors: Boerboom Chris M. , Wyse Donald L.
Published: March 2018

Canada thistle [Cirsium arvense[L.] Scop. # CIRAR] is a major weed problem in birdsfoot trefoil (Lotus corniculatusL. ‘Norcen’) seed production in northern Minnesota. Several systemic herbicides applied with selective applicators (roller and ropewick) were evaluated for Canada thistle control in birdsfoot trefoil. Picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid), clopyralid (3,6-dichloro-2-pyridinecarboxylic acid), and glyphosate [N-(phosphonomethyl)glycine] controlled Canada thistle better than MCPA [(4-chloro-2-methylphenoxy)acetic acid] and dicamba (3,6-dichloro-2-methoxybenzoic acid). Glyphosate and MCPA did not injure birdsfoot trefoil foliage or bloom, whereas, picloram, clopyralid, and dicamba injured both. Although selective applications of glyphosate controlled Canada thistle for a short term with the least birdsfoot trefoil injury, long-term Canada thistle control in birdsfoot trefoil does not appear feasible with selective herbicide applications.
Herbicides and Cultivation for Sicklepod,Cassia obtusifolia, Control in Soybeans,Glycine max
Authors: Shaw David R. , Coats G. Euel
Published: March 2018

Sicklepod control with one or two cultivations or postemergence (POE) directed-spray applications of linuron or metribuzin plus 2,4-DB was less than 50% in August evaluations when no soil-applied herbicide had been used. However, sicklepod control greater than 75% was noted through August when two cultivations or metribuzin plus 2,4-DB applied POE followed either metribuzin applied preplant incorporated (PPI) and preemergence (PRE) or metribuzin plus alachlor applied as a PRE treatment. One cultivation after these soil-applied herbicide treatments did not reduce sicklepod populations compared to the chemical treatments alone. Soybean yields more than doubled over yields in untreated plots when a combination of soil-applied herbicides and two cultivations or metribuzin plus 2,4-DB applied POE were used.
Interaction Between Weed Control and Loblolly Pine,Pinus taeda, Seedling Quality
Authors: Mitchell Robert J. , Zutter Bruce R. , South David B.
Published: March 2018

Third-year heights, third-year root-collar diameters, and 3 yr volume growth of loblolly pine seedlings were examined in relation to a) root-collar diameter class at time of planting and b) herbaceous weed control. Treatments were a) no weed control and b) complete control for 2 yr. For both weed control treatments, means for third-year heights, groundline diameters, and volume growth were related positively to initial seedling diameter. The influence of initial seedling diameter on third-year diameters and heights did not differ among weed control treatments. However, the influence of initial diameter on volume growth did differ among weed control treatments. Thus, when using herbaceous weed control, additional gains in early volume growth can be realized by planting seedlings with large root-collar diameters.
Bounty Programs — An Effective Weed Management Tool
Authors: Lacey Celestine A. , Egan Charles , Pearson Wayne , Fay Peter K.
Published: March 2018

Residents in Stillwater County, MT, used a weed bounty program as an educational tool to promote awareness, detection, and control of spotted knapweed (Centaurea maculosaLam. # CENMA) on range and noncropland. Many people became involved with the weed control effort, weed awareness was increased, spotted knapweed was controlled, and the program was cost effective. The success of a weed bounty program is influenced by 1) the enthusiasm and innovations of the county extension agent, weed supervisor, or other key individual or group in the community; 2) the choice of the weeds selected; and 3) good media coverage of the bounty program. With proper planning and organization, weed bounty programs effectively promote awareness and action in other areas of public concern.