bluuebunny/crossref_metadata_2025 huggingface dataset:
Weed Control by Spring Cover Crops and Imazethapyr in No-till Southern Pea (Vigna unguiculata)
Authors: Burgos Nilda R. , Talbert Ronald E.
Published: March 2018

Studies were conducted at the Vegetable Substation in Kibler, AR, in 1992 and 1993, in the same plots, to evaluate weed suppression by spring-seeded cover crops and to determine the effects of cover crop and imazethapyr on no-till southern pea. A plot without cover, conventionally tilled before planting southern pea, served as control. Weed control treatments, applied as subplots in each cover crop, included a weedy check, handweeded check, and half and full rates of imazethapyr (0.035 and 0.07 kg/ha) followed by sethoxydim (0.22 kg/ha). Biomass of Palmer amaranth 6 WAR without herbicides, was less in Italian ryegrass and sorghum-sudangrass residues than in oat residue and no cover crop. Over the years, Palmer amaranth density increased 333% without cover crops and 28% with cover crops. Rice flatsedge density increased four to five times in oat and sorghum-sudangrass residues but remained the same in Italian ryegrass residue. In general, Italian ryegrass residue suppressed the most weeds. Oat residue was least suppressive. Italian ryegrass and sorghum-sudangrass also reduced southern pea stand. Regardless of cover crop and year, half and full rates of imazethapyr followed by sethoxydim equally reduced density of Palmer amaranth, goosegrass, large crabgrass, southwestern cupgrass, and rice flatsedge compared with the untreated check. Residual control of Palmer amaranth by imazethapyr was higher at the full rate than the reduced rate, regardless of cover crop. Half rate of imazethapyr followed by sethoxydim controlled 94 to 100% of Palmer amaranth, rice flatsedge, large crabgrass, and southwestern cupgrass late in the season, regardless of cover crop in 1992 and 1993. Southern pea yield in untilled plots with cover crops was two to three times lower than yield in plots with preplant tillage and no cover crops mostly because of reduction in crop stand in the presence of cover crops.
Herbicides for Winter-hardy Wild Oat (Avena fatua) Control in Winter Wheat (Triticum aestivum)
Authors: Koscelny Jeffrey A. , Peeper Thomas F.
Published: March 2018

Diclofop at 840 g ai/ha, fenoxaprop at 90 g ai/ha, and imazamethabenz at 530 g ai/ha fall-applied controlled wild oat 96, 99, and 95% and increased wheat grain yields 26, 29, and 24%, respectively. These herbicides controlled wild oat over a wider range of growth stages than current labels indicate. The same treatments applied in March were less effective for wild oat control and did not increase wheat yield.
Fruiting Response of Cotton (Gossypium hirsutum) to Pyrithiobac
Authors: Allen Ralph L. , Snipes Charles E. , Crowder Scotty H.
Published: March 2018

Field experiments were conducted in 1991 and 1992 near Stoneville, MS and Greenville, MS, to determine the impact of pyrithiobac on cotton fruiting, maturity, and yield. Trials were conducted in areas maintained weed-free with standard production practices to optimize yields. Pyrithiobac was applied at 105 or 210 g ae/ha either PRE or POST to cotton in the cotyledon to 2-leaf, 5- to 7-leaf, and matchhead-square (MHS) stages of growth. At one location, monosodium salt of methylarsonic acid (MSMA) and fluometuron plus MSMA were applied as standard comparisons. At the Stoneville location, injury 1 wk after treatment (WAT) with pyrithiobac ranged from 2.5% with 105 g/ha applied at cotyledon to 2-leaf to 26% with 210 g/ha applied at MHS. Injury was transient in nature and was rarely detectable 4 wk after treatment in either year. Injury was not evaluated at the Greenville location. At Stoneville, a reduction in height occurred with MHS applications of pyrithiobac and MSMA. There was no reduction in yield for any treatment compared to the untreated check in 1991 at Stoneville and in both years at Greenville. In 1992 at Stoneville, treatments of 210 g/ha pyrithiobac, MSMA, and fluometuron plus MSMA at all application timings reduced yield. Pyrithiobac at 105 g/ha applied PRE also reduced yield. Greatest yield loss occurred with treatments of MSMA applied at MHS. There were no yield reductions at either location with postemergence application of 105 g/ha pyrithiobac.
Sethoxydim and Crop Oil Concentrate Increase Pyridate Phytotoxicity in Transplanted Cabbage (Brassica oleracea)
Authors: Bellinder Robin R. , Kirkwyland Jonathan , Wallace Russell W. , Arsenovic Marija
Published: March 2018

Greenhouse and field studies were conducted in 1991 and 1992 to determine the potential for interaction among pyridate (0.5, 1.0 kg ai/ha), sethoxydim (0.22 kg ai/ha), and crop oil concentrate (COC) (1.25% v/v) applied alone or in two- and three-way combinations to transplanted cabbage. Additionally, the effect of applying sethoxydim and COC 1 and 2 d before and after application of pyridate was investigated. In greenhouse-grown cabbage, injury increased twofold and dry weight was reduced 15% when pyridate dose was doubled. Sethoxydim increased pyridate injury significantly, reducing dry weight 31%. When COC was applied with pyridate, injury increased and dry weight decreased linearly. Despite substantial crop injury 7 d after treatment with pyridate alone, pyridate + sethoxydim, and pyridate + COC, yields of field-grown cabbage were reduced significantly in 1 yr only when the three materials were combined. Pyridate injury decreased as time between sethoxydim + COC applications, before and after pyridate was applied, increased.
Proso Millet (Panicum miliaceum) Response to CGA-152005, Metsulfuron, and Triasulfuron
Authors: Uludag Ahmet , Lyon Drew J. , Nissen Scott J. , Kachman Stephen D.
Published: March 2018

Proso millet is a short-season summer annual grass that is well adapted to the central Great Plains. Proso millet is commonly planted as a summer crop when winter wheat stands are lost due to adverse conditions. Sulfonylurea herbicides labeled for use in winter wheat prohibit planting proso millet for intervals up to 10 mo following application. A series of greenhouse and field studies determined proso millet tolerance to CGA-152005, metsulfuron, and triasulfuron soil residue. In the greenhouse, proso millet was not affected by soil-applied CGA-152005 at doses up to 160 g ai/ha, while metsulfuron and triasulfuron doses of 4 and 15 g ai/ha, respectively, inhibited proso millet biomass accumulation. In the field, metsulfuron and triasulfuron caused early season stunting and chlorosis at doses two to four times those recommended; however, grain yields were not affected. Organic matter and clay content were highly correlated with proso millet growth response to the herbicides under greenhouse conditions, but in the field, soil pH may have influenced herbicide bioavailability.
Sicklepod (Senna obtusifolia) Control in Soybean (Glycine max) with Single and Sequential Herbicide Applications
Authors: Watts Jeffrey R. , Murdock Edward C. , Stapleton Gregory S. , Toler Joe E.
Published: March 2018

Field studies were conducted in 1991 to 1993 to determine the effects of PRE and POST herbicides alone and in factorial combinations on sicklepod control, weed biomass, and soybean seed yields. Herbicides evaluated were metribuzin PRE, metribuzin + chlorimuron PRE, imazaquin PRE and POST, chlorimuron POST, and AC 263,222 POST POST herbicides alone provided better sicklepod control than PRE herbicides alone. However, sequential (SEQ) treatments [PRE followed by (fb) POST] provided better sicklepod control than single herbicide treatments. Metribuzin and metribuzin + chlorimuron alone or used in a SEQ program provided similar PRE control of sicklepod, and both controlled sicklepod better than imazaquin in 1991 and 1992. Chlorimuron alone or in a SEQ program provided better POST control than AC 263,222 or imazaquin alone when soil moisture levels at planting favored weed seed germination. When soil moisture levels at planting were unfavorable for weed seed germination, the residual activity of imazaquin provided the best season-long control. SEQ herbicide applications allowed soybean to attain higher seed yields than single (PRE or POST) herbicide treatments all 3 yr. However, only metribuzin fb chlorimuron in 1991 and 1992 and imazaquin fb imazaquin and imazaquin fb chlorimuron in 1993 allowed soybean to achieve seed yields similar to weed-free soybean. Soybean seed yields were greater with POST than with PRE herbicides 2 of 3 yr, but no single herbicide treatment provided soybean seed yields similar to weed-free soybean.
Tolerance of Sweet Corn (Zea mays) Hybrids to RPA 201772
Authors: Van Wychen Lee R. , Harvey R. G. , Rabaey Thomas L. , Bach David J.
Published: March 2018

Field studies at Arlington, WI, and LeSueur, MN, were conducted in 1996 and 1997 to evaluate tolerance of six sweet corn hybrids to RPA 201772 applied preemergence at 79 to 210 g/ha. Both years the most sensitive hybrid at the Wisconsin site was ‘Zenith,’ with yield reductions of 14 and 22% at 210 g/ha (twice the labeled rate). ‘Excellency,’ ‘Green Giant 43,’ and ‘Jubilee’ tolerated RPA 201772 at 158 g/ha or less. The least tolerant hybrids in Minnesota were ‘Green Giant 6′ and Jubilee, and the most tolerant hybrids were Green Giant 43 and ‘Rogers 9056.’ Injury from RPA 201772 increased as application dose increased. The greatest risk of injury from RPA 201772 appear to be with Green Giant 6, Zenith, and Jubilee, especially on coarser textured soils with low organic matter. Excellency, Green Giant 43, and Rogers 9056 appeared to be the most tolerant. Because of the differential hybrid response to RPA 201772 across sites and years, more hybrid response data needs to be generated before RPA 201772 is labeled in sweet corn.
Bahiagrass (Paspalum notatum) Seedhead Suppression Following Consecutive Yearly Applications of Plant Growth Retardants
Authors: Baker Robert D. , McCarty Lambert B. , Colvin Daniel L. , Higgins Jeffery M. , Weinbrecht Jan S. , Moreno Jorge E.
Published: March 2018

Field trials evaluated sequential applications of plant growth retardants (PGRs) to bahiagrass for a 3-yr period at two Florida locations: Newberry (north Florida) and Okeechobee (south Florida). Seven PGRs from various chemical families were used: glyphosate, fluazifop, sethoxydim, maleic hydrazide, trinexapac-ethyl, imazapic, and imazaquin. In 1991 and 1992, PGRs reduced turf color for 2 to 4 wk after treatment (WAT) at the Newberry location but remained above acceptable levels (> 5.0) and recovered by 6 WAT. In 1993, glyphosate, fluazifop, and maleic hydrazide reduced turf color below acceptable levels (< 5.0) 4 WAT, but turf color was acceptable by 6 WAT. Turf color was slightly reduced following single and sequential imazapic applications in Okeechobee; however, turf recovered by 8 WAT. Cumulative seedhead suppression at both locations increased during the 3 yr resulting in at least a 60% reduction in seedhead numbers. Seedhead production each year was 10 to 50% less at 12 WAT in treated plots than in the previous year. Single applications of imazapic and imazapic + imazaquin provided 85 to 100% seedhead suppression for 12 WAT and 100% suppression for up to 16 wk following sequential applications made 8 wk after the initial application (WAI). Single applications of glyphosate, fluazifop, and maleic hydrazide provided ≥ 70% seedhead suppression for 4 to 8 WAT. Sequential applications of fluazifop made 8 WAI provided > 70% control of seedheads through 8 to 16 WAI for 3 yr.
Tractor Wheel Traffic Effects on Weed Emergence in Central Iowa
Authors: Jurik Thomas W. , Zhang Shuyu
Published: March 2018

The effects of tracking by tractor wheels on the emergence of common weed species of central Iowa were studied near Ames, IA, in 1996 and 1997. Seedling emergence in tracked and nontracked interrow areas, soil water content, and soil temperature were monitored for 8 to 10 wk after planting of soybean (Glycine max). Compared to nontracked interrow areas, a single wheel-tracking pass at crop planting increased the cumulative number of seedlings of giant (Setaria faberi) and yellow foxtails (S. glauca) by 187%, common waterhemp (Amaranthus rudis) by 102%, and common lambsquarters (Chenopodium album) by 30%. There was little effect of wheel traffic on velvetleaf (Abutilon theophrasti) emergence. After planting, soil water content to a depth of 5 cm was higher in tracked areas than in nontracked areas, but after 6 wk there was no difference. Soil temperature at 4- to 5-cm depth was similar in tracked and nontracked interrows. Compaction from wheel traffic apparently did not create a physical impediment to emergence; rather, it altered micro-environmental conditions in ways that stimulated weed germination and emergence.
Mode of Resistance of Triazine-Resistant Annual Bluegrass (Poa annua)
Authors: Kelly Steven T. , Coats G. Euel , Luthe Dawn S.
Published: March 2018

Two previously identified triazine-resistant annual bluegrass (Poa annua) biotypes in Mississippi were evaluated to determine the level as well as the mode of resistance compared to a triazine-susceptible biotype. Annual bluegrass seeds were collected at two sites (Meridian and Tupelo, MS) from field plots previously treated with 11.2 kg ai/ha simazine. Seeds were planted on agar containing simazine (0, 0.001, 0.01, 0.1, 1, 10, or 100 mM) or diuron (0, 0.01, 0.1, 1, 10, 100, or 1,000 μM), placed in the growth chamber with an 8 h daylength and alternating temperatures of 15 and 20 C, and allowed to grow for 3 wk, after which fresh weight was determined. Data were subjected to regression analyses and the amount of simazine or diuron required to reduce fresh weight to 50% of the untreated plants was determined. These data indicated a greater than 1,000-fold level of resistance to simazine with either biotype. Diuron concentrations of 5.0, 3.0, and 3.2 μM were required to reduce fresh weight to 50% of the untreated for the triazine-susceptible, Meridian, and Tupelo biotypes, respectively. Sequencing a portion of the chloroplastpsbAgene revealed a serine 264 to glycine mutation, which reduced the affinity of the triazine herbicides for the QB-binding niche on the D1 protein in photosystem II.
Barnyardgrass (Echinochloa crus-galli) Control in Dry-Seeded Rice (Oryza sativa) with Soil-Applied and Postemergence Herbicide Programs
Authors: Jordan David L. , Miller Donnie K. , Crawford Stephen H.
Published: March 2018

A study was conducted from 1994 through 1996 to evaluate barnyardgrass control, rice yield, and estimated economic returns with delayed preemergence (DPRE) applications of pendimethalin, quinclorac, thiobencarb, pendimethalin plus quinclorac, and pendimethalin plus thiobencarb applied alone or followed by postemergence (POST) applications of propanil or propanil plus molinate. Late-season barnyardgrass control with pendimethalin plus quinclorac was greater than with pendimethalin, quinclorac, thiobencarb, or pendimethalin plus thiobencarb. Control with pendimethalin, quinclorac, and pendimethalin plus thiobencarb exceeded that with thiobencarb. Propanil plus molinate controlled barnyardgrass more effectively than propanil. Quinclorac and pendimethalin plus quinclorac were the only DPRE herbicide treatments where yield and estimated economic returns were not improved by POST herbicides.
Weed Control and Crop Injury in Ecofallow Corn (Zea mays) Using Imazethapyr
Authors: Wicks Gail A. , Mahnken Garold W. , Hanson Gordon E.
Published: March 2018

Imidazolinone-resistant and -tolerant corn hybrids give growers a new weed control option. Field experiments were conducted in 1993 and 1994 to evaluate imazethapyr for controlling weeds in no-till corn planted into winter wheat stubble in a winter wheat–ecofallow corn rotation. Imidazolinone-tolerant (IT) and imidazolinone-resistant (IR) corn were protected genetically from injury by imazethapyr that was applied preplant, preemergence, or postemergence to ‘Pioneer Brand 3417,’ ‘Pioneer Brand 3417 IR,’ ‘ICI Seeds 8532,’ and ‘ICI Seeds 8532 IT’ hybrids. No difference in corn injury occurred between IR and IT corn. Imazethapyr applied to resistant or tolerant corn hybrids could be used to control weeds in ecofallow corn. Imazethapyr at 35 or 70 g ai/ha controlled triazine-resistant kochia better than the standard herbicide treatment of metolachlor plus cyanazine.
Influence of Adjuvants and Formulation on Barnyardgrass (Echinochloa crus-galli) Control with Propanil in Rice (Oryza sativa)
Authors: Jordan David L. , Burns Ann B. , Barnes C. Jeff , Barnett Wayne , Herrick J. Kelly
Published: March 2018

Experiments were conducted to compare barnyardgrass control and rice injury and yield with emulsifiable concentrate and dry flowable formulations of propanil as single or repeat applications with crop oil concentrate, methylated seed oil, a blend of organosilicone surfactant and methylated seed oil or conventional nonionic surfactant, and organosilicone surfactant. Two applications of propanil were more effective in controlling barnyardgrass than a single application. The emulsifiable concentrate formulation of propanil controlled barnyardgrass more effectively than the dry flowable formulation in some but not all experiments. Differences in barnyardgrass control with propanil as influenced by adjuvants were minor and inconsistent. The most consistent barnyardgrass control and the highest rice yields were obtained with repeat applications of the emulsifiable concentrate formulation of propanil.
Differential Varietal Response of Green Pea (Pisum sativum) to Metribuzin
Authors: Al-Khatib Kassim , Libbey Carl , Kadir Sorkel , Boydston Rick
Published: March 2018

Field and greenhouse experiments evaluated the differential response of 15 green pea varieties to metribuzin applied preemergence. ‘Charo,’ ‘CMG 298,’ ‘Leah,’ ‘Scout,’ and ‘Puget’ were the most tolerant, whereas ‘Bolero’ and ‘Sundance’ were the most susceptible varieties under greenhouse conditions. Variable chlorophyll fluorescence (Fv), efficiency of photosystem II (Fv/Fmax), and leaf area were reduced sharply by metribuzin in susceptible varieties, and metribuzin susceptibility correlated highly with the reduction in shoot dry weight. Green pea varieties grown under field conditions responded to metribuzin similarly to pea varieties grown under greenhouse conditions. Metribuzin reduced shoot dry weight more in peas grown at 30/25 C than in those grown at 25/20 and 20/15 C. Also, metribuzin injured peas more when grown in soil saturated to field capacity compared to soil at 70 and 40% of field capacity.
Oviposition Site Preferences ofGalerucella calmariensisandG. pusilla, Biological Control Agents of Purple Loosestrife (Lythrum salicaria)
Authors: Lindgren Cory John
Published: March 2018

Oviposition site preferences forGalerucella calmariensisandG. pusilla, biological weed control agents against purple loosestrife, were examined in 1994 and 1995. The leaves, stems, axils, and flower buds (G. pusilladid not oviposit on flower buds) were found to be the preferred oviposition sites. Oviposited egg masses may be used as a parameter within a biological control monitoring plan, providing information onGalerucellaestablishment and/or presence, estimating future population size, and providing biological control agent dispersal information. Monitoring for egg masses should concentrate on host plant leaves, where over 56% of all egg masses were oviposited.
Fumitory (Fumaria officinalis L.)
Authors: Mitich Larry W.
Published: March 2018

Fumitory (Fumaria officinalis L.) is a member of Fumariaceae, a family of annual and perennial herbs, whose best-known genera, in addition to Fumaria, are Corydalis and Dicentra (bleeding heart and Dutchman's breeches). Fumariaceae is mainly a temperate family that embraces 16 genera and 400 species. Economically, its use is limited to garden ornamentals (Heywood 1993). Brummitt (1992) and Hyam and Pankhurst (1995) place fumitory in Papaveraceae, but most authorities, including Mabberley (1989), put it in Fumariaceae.
Effect of Tillage and Application Method on Corn (Zea mays) Response to Imidazolinone Residues in Soil
Authors: Renner Karen A. , Schabenberger Oliver , Kells James J.
Published: March 2018

Field studies on a sandy loam soil determined the influence of application method and rate and subsequent tillage on corn response to imazaquin and imazethapyr residues remaining in the soil. Imazaquin was applied preplant incorporated (PPI) and preemergence (PRE) at 70, 140, and 280 g ai/ha and postemergence (POST) at 70 and 140 g/ha. Imazethapyr was applied PPI and PRE at 70, 105, and 140 g ai/ha and POST at 70 and 105 g/ha. Subsequent tillage included fall moldboard plowing followed by spring field cultivation, fall chisel plowing followed by spring field cultivation, and no tillage. Herbicide dissipation was determined by analyzing soil cores taken in the spring at the time of corn planting and by measuring corn height and grain yield. Imidazolinone residues were detected in only 1 of 2 yr. Imazaquin was detected more frequently than imazethapyr. Imazaquin concentrations in the upper 10 cm of soil 11 mo after a PPI application of 280 g/ha were 5, 6, and 7 ng/g of soil in moldboard plow, chisel, and no-tillage systems, respectively. Imazaquin (5 ng/g) was also detected in the 10–18-cm soil depth in the moldboard plow system. Corn height and grain yield were not reduced from imazaquin or imazethapyr, regardless of application method or rate in any tillage system.
Distribution, Biology, and Management of Diffuse Knapweed (Centaurea diffusa) and Spotted Knapweed (Centaurea maculosa)
Authors: Sheley Roger L. , Jacobs James S. , Carpinelli Michael F.
Published: March 2018

Diffuse knapweed, a biennial or short-lived perennial, and spotted knapweed, a perennial, are taprooted Eurasian weeds invading rangeland in the western United States and Canada. Knapweed (Centaureaspp.) invasion is associated with reductions in biodiversity, wildlife, and livestock forage, and increased erosion. Spotted knapweed grows to about 1 m and usually has purple flowers, whereas diffuse knapweed is slightly shorter, usually with white flowers. Persistent flower bracts on diffuse knapweed bear a rigid terminal spine about 8 mm long with four or five pairs of shorter lateral spines. Bracts on spotted knapweed have dark spotted tips. Knapweed management involves a combination of containing infestations and control efforts. Hand pulling in areas with small infestations can be effective for controlling spotted and diffuse knapweeds. Picloram applied at 0.28 kg ha−1provides control for about 3 yr. Effective long-term control of knapweeds requires periodic applications of picloram, which are only cost-effective on highly productive range sites with a residual grass understory. About 12 insect species have been released for knapweed biocontrol. Seed production has been reduced by 46% by insects feeding in the flower heads. Although insects have not reduced spotted knapweed densities, they may stress the weed and shift the competitive balance to associated species. Sheep grazing reduces the density of very young seedlings and may limit seedling recruitment into the population. In areas without a residual understory of desired plant species, revegetation of knapweed-infested rangeland is required. Components of any integrated weed management program are sustained effort, constant evaluation, and the adoption of improved strategies.
Evaluation of V-10029 and Trinexapac-Ethyl for Annual Bluegrass Seedhead Suppression and Growth Regulation of Five Cool-Season Turfgrass Species
Authors: Fagerness Matthew J. , Penner Donald
Published: March 2018

An experimental turfgrass growth regulator, V-10029, was compared with trinexapac-ethyl, a growth regulator used commonly on highly maintained turfgrasses, to evaluate growth suppression patterns and suppression of seedhead formation; the latter was evaluated on turfgrass species and annual bluegrass, a weedy species that appeared and developed seedheads in tall fescue. Plugs of creeping red fescue, Kentucky bluegrass, perennial ryegrass, and creeping bentgrass were taken from the field into a greenhouse. V-10029 at three rates (0.015, 0.029, and 0.059 kg/ha) was compared to an untreated control and trinexapac-ethyl at a label rate (0.382 kg/ha for perennial ryegrass and 0.287 kg/ha for the other four species). Of the eight replications for each treatment, four were not mowed for the purpose of evaluating suppression of seedhead formation, and four were used for weekly clipping collection to evaluate growth suppression. Compared to the untreated control, V-10029 at all three applied rates caused significant seedhead suppression in both tall fescue infested with annual bluegrass (> 90%) and perennial ryegrass (50 to 80%). Trinexapac-ethyl was not as effective, causing seedhead suppression levels of 57% in annual bluegrass found in tall fescue and 43% in perennial ryegrass. V-10029 caused unacceptable levels of discoloration (> 20%) in all turfgrass species, and discoloration increased with increasing rates of application. Patterns of growth suppression for tall fescue, Kentucky bluegrass, and perennial ryegrass, in response to V-10029 at all rates and to trinexapac-ethyl, were similar on a percent of suppression basis. Growth of creeping bentgrass was suppressed by V-10029 only at high rates. In contrast, creeping red fescue was significantly injured by V-10029 at all rates. The greatest growth suppression, in response for all treatments, occurred 2 to 3 wk after application. The effect of trinexapac-ethyl dissipated after 4 wk, while V-10029 was effective until 5 to 7 wk after treatment. Observed effects of V-10029 were consistent with its activity as an ALS-inhibiting herbicide and, therefore, as a Class D turfgrass growth regulator.
Interaction of Bromoxynil and Postemergence Graminicides on Large Crabgrass (Digitaria sanguinalis)
Authors: Culpepper A. Stanley , York Alan C. , Jennings Katherine M. , Batts Roger B.
Published: March 2018

The effect of bromoxynil on large crabgrass control by clethodim, sethoxydim, fluazifop-P, fluazifop-P plus fenoxaprop-P, and quizalofop-P was evaluated in 1996 and 1997 in bromoxynil-tolerant cotton and in fallow areas. Bromoxynil at 560 g ai/ha reduced large crabgrass control 4 weeks after treatment (WAT) when mixed with labeled rates of fluazifop-P, fluazifop-P plus fenoxaprop-P, or quizalofop-P. Control 9 WAT was reduced when bromoxynil was mixed with any of the graminicides. Antagonism with the mixtures was greatest with quizalofop-P, intermediate with fluazifop-P plus fenoxaprop-P and fluazifop-P, and least with clethodim and sethoxydim. Increasing the graminicide rate 50% in mixtures with bromoxynil alleviated antagonism only for clethodim. No antagonism was noted 9 WAT when bromoxynil was applied 3 d before or 3 d after application of clethodim or sethoxydim or when bromoxynil was applied 3 d after fluazifop-P plus fenoxaprop-P. Antagonism was observed when bromoxynil was applied 3 d before fluazifop-P plus fenoxaprop-P or when applied 3 d before or 3 d after fluazifop-P and quizalofop-P. Regardless of bromoxynil application, greatest yields were obtained from cotton treated with clethodim or sethoxydim. Bromoxynil applied 3 d before or 3 d after clethodim, sethoxydim, or fluazifop-P plus fenoxaprop-P did not reduce yield. Yield was reduced when bromoxynil was applied 3 d before or 3 d after application of fluazifop-P or quizalofop-P and when bromoxynil was mixed with any graminicide.
Using the Rosette Technique for Canada Thistle (Cirsium arvense) Control in Row Crops
Authors: Miller Brett R. , Lym Rodney G.
Published: March 2018

Clopyralid applied to Canada thistle rosettes has provided better control in the following growing season than applications to bolted plants. The objectives of this research were to determine if using cultivation to prevent plants from bolting prior to herbicide application (the rosette technique) could be successfully incorporated into a row crop production system and to evaluate the effect of Canada thistle growth stage on the absorption and translocation of14C-clopyralid. Canada thistle control 8 mo after postharvest herbicide treatment (MAFT) using the rosette technique was similar to control when using conventional in-crop plus postharvest herbicide treatments in corn and soybean. Glyphosate and clopyralid plus 2,4-D were the most consistent postharvest herbicide treatments for Canada thistle control 8 MAFT in corn and soybean. Corn yields were similar, but soybean yields were slightly lower when Canada thistle was controlled using cultivation compared to conventional herbicide treatments.14C-clopyralid translocation to Canada thistle roots and lower shoot parts was greater when clopyralid was applied to the rosette stage than when applied to bolted Canada thistle plants. The increased translocation probably accounts for the increased Canada thistle control observed in the field. Incorporating the rosette technique into a weed management program should allow growers to control Canada thistle with less herbicide input than do standard practices.
Spectacular Increases in Crop Yields in the United States in the Twentieth Century
Authors: Warren G. F.
Published: March 2018

About 15 years ago, I heard several speakers saying that our crop yields were “leveling off.” This stimulated me to assemble data on the subject. The result is shown in Table 1, which gives the U.S. average yields for 10-yr periods during this century for nine crops. The increases are spectacular, varying from two- to sevenfold. Factors contributing to these increases differ from crop to crop. To obtain information on this subject, several experts on each crop were consulted, and their conclusions are summarized in the following text. Only those factors contributing to increased yields are covered. However, great improvements in efficiency of production, product quality, and reduction in soil erosion also have occurred as cultivars and production practices have changed. For most of the crops, increases in yields started in the 1940s and have increased dramatically during the rest of the century. We have not attempted to predict the future at this time, but the rate at which yields are increasing does not appear to be slowing.
Effect of Pyrithiobac, MSMA, and DSMA on Cotton (Gossypium hirsutumL.) Growth and Weed Control
Authors: Monks C. Dale , Patterson Michael G. , Wilcut John W. , Delaney Dennis P.
Published: March 2018

Field experiments were conducted at one location in Georgia (1994) and at two locations in Alabama (1994 and 1995) to evaluate the effects of MSMA or DSMA plus pyrithiobac applied postemergence (POST) in cotton. Pyrithiobac at 0.07 kg ai/ha was applied POST alone or in combination with MSMA at 1.1 kg ai/ha or DSMA at 1.7 kg ai/ha at the pinhead square stage of cotton growth. Cotton was tolerant to the POST applications of pyrithiobac. Adding MSMA or DSMA to pyrithiobac injured cotton similar to MSMA or DSMA applied alone. Plant mapping data indicated that all treatments had no effect on height : node ratio, reproductive or vegetative node production, or square retention at the first or second fruiting position. Cotton maturity response to MSMA and DSMA ranged from no effect to delayed maturity. Adding DSMA to pyrithiobac increased Florida beggarweed and common cocklebur control over pyrithiobac applied alone in 1995 but did not increase control in 1994. Adding DSMA to pyrithiobac increased sicklepod control over pyrithiobac applied alone in the three site years it was rated in the Alabama tests. Where sicklepod is present, the addition of an arsenical herbicide to pyrithiobac will generally increase control but has the potential to delay maturity and decrease cotton yield equal to the arsenical herbicide applied alone.
Temperature, Adjuvants, and UV Light Affect Sethoxydim Phytotoxicity
Authors: Matysiak Robert , Nalewaja John D.
Published: March 2018

Experiments were conducted using oat in the greenhouse to determine phytotoxicity and spray deposit characteristics of sethoxydim on oat as influenced by adjuvants, ultraviolet (UV) light, and temperature at and shortly after application. Petroleum oil of low viscosity was equal or more effective with sethoxydim when applied at 10 than at 25 C, but high-viscosity petroleum oil was more effective at 25 than at 10 C. UV light reduced sethoxydim efficacy more for high- than low-viscosity petroleum oil adjuvant at 25 C, but not at 10 C. Commercial vegetable oil adjuvant was less effective with sethoxydim at 10 than at 25 C, and UV light reduced efficacy at both temperatures. Commercial methylated vegetable oil was the most effective adjuvant and efficacy was only slightly reduced by UV light at 25 C. A secondary alcohol surfactant that is considered hydrophilic enhanced sethoxydim efficacy even when exposed to UV light. Adjuvants that gave discernible uniform spray deposits with close contact to the epicuticular surface, including over anticlinal walls, resulted in the most effective treatments. The results indicated that temperature at application is important to adjuvant efficacy, partly because of the effect on spray deposit characteristics.
Preherbicide Mowing and Herbicide Rate on Tropical Soda Apple (Solanum viarum) Control
Authors: Mislevy Paul , Mullahey J. Jeffrey , Martin Frank G.
Published: March 2018

Field studies were conducted in 1993–1994 and 1994–1995 to evaluate the effects of preherbicide mowing and herbicide rate on tropical soda apple (TSA) control. Mature TSA plants were mowed one, two, or three times to a 7.5-cm stubble with a 60-d interval between mowings. Triclopyr was applied at 0, 0.6, and 1.1 kg ai/ha at 375 L/ha at 207 kPa 60 d after each mowing treatment. Mowing TSA plants twice before an application of 0.6 kg ai/ha triclopyr resulted in 100% control. Tropical soda apple control (2-yr average) for the triclopyr treatment increased between one (28% control) and two (82% control) preherbicide mowings, with no additional control benefits from three mowings (84% control). In a second study, TSA control increased from 10% 60 d after a single mowing to 92% after three consecutive mowings at 60-d intervals with no herbicide. Total nonstructural carbohydrates in TSA crowns decreased from 19.1% for unclipped plants to 4.3% 60 d after three preherbicide mowings.
Nature of the Interference Mechanism of Mugwort (Artemisia vulgaris)
Authors: Inderjit  , Foy Chester L.
Published: March 2018

Mugwort is a noxious perennial weed that interferes with the growth and establishment of crop species. The present study was designed to understand the role of allelopathy as a potential mechanism of interference by mugwort. Soils amended with mugwort plant material and leachates were analyzed for their chemical characteristics. The effect of amended soils on seedling growth of red clover was studied. The influence of NP fertilization and charcoal on modification of allelopathic potential of amended soils, in terms of their effect on soil characteristics and red clover seedling growth, was also investigated. In addition, red clover seedling growth was compared in sterilized and nonsterilized soils amended with mugwort leachate and NP fertilization. In general, addition of mugwort leachates and plant matter (amended soil) resulted in chemical changes in soil, including changes in available phenolics. Red clover seedling growth was reduced in amended soils, when compared to that in nonamended soils. Although the different amounts of NP fertilization in nonsterilized soil amended with mugwort leachate could not counteract its interference to red clover growth (root reduction, 67–79%; shoot reduction, 34–44%), the addition of charcoal did eliminate leachate effects on red clover growth. This indicates the probable allelopathic interference of mugwort to red clover growth. Addition of NP fertilization might have resulted in higher microbial activity, which is likely to influence qualitative and/or quantitative availability of phenolic compounds. Data on phenolic levels and red clover growth in sterilized and nonsterilized soil amended with mugwort leachate and NP fertilization indirectly indicate the significance of soil microbes in mugwort interference to red clover.
Seed Depth Influence on Mexican Sunflower (Tithonia diversifolia) Emergence and Control
Authors: Ayeni Albert O. , Agbato Samuel O. , Majek Bradley A.
Published: March 2018

Experiments were conducted in pots and in the field to determine the influence of seed depth on seedling emergence pattern and control of Mexican sunflower with or without imazethapyr plus pendimethalin. Mexican sunflower seeds were placed at 0-, 2.5-, 5-, 7.5-, and 10-cm soil depths, and imazethapyr–pendimethalin mixture was applied PRE at 0, 0.05 + 0.65, 0.09 + 1.31, and 0.18 + 2.62 kg ae (+ ai)/ha. Mexican sunflower emergence was 57, 30, 14, 3, and 2% from 0-, 2.5-, 5-, 7.5-, and 10-cm seed depths, respectively. Seedling emergence started 2 to 3 d after planting and continued for 4 to 5 d. At 0- to 5-cm seed depths, 84 to 100% of total seedling emergence occurred within 3 d after the first seedling emerged, but emergence rate was less from 7.5- and 10-cm seed depths. Imazethapyr plus pendimethalin at 0.05 + 0.65 and 0.09 + 1.31 kg/ha had no effect on seedling emergence in Mexican sunflower, but subsequent growth was severely inhibited regardless of seed depth. The herbicide treatments were more injurious to Mexican sunflower seedlings that emerged from 5- to 10-cm depths than to those that emerged from 0 and 2.5 cm. Burying seeds 7.5 cm deep or more is a potential control measure for Mexican sunflower, and the deeper the emergence depth, the more susceptible the seedling is to imazethapyr plus pendimethalin.
Weed Control and Economic Returns with Postemergence Herbicides in Narrow-Row Soybeans (Glycine max)
Authors: Johnson William G. , Kendig J. Andrew , Massey Raymond E. , Defelice Michael S. , Becker Chad D.
Published: March 2018

Field studies were conducted at three sites in 1993 and 1994 to evaluate weed control, crop response, and economic returns to 0.5× and 1× postemergence rates of chlorimuron, chlorimuron plus quizalofop, bentazon plus acifluorfen, fluazifop plus fenoxaprop, imazethapyr, and imazethapyr plus clethodim in no-till narrow-row soybean production. Common lambsquarters, ivyleaf morningglory, and common ragweed were controlled equally with 0.5× rates applied early postemergence and 1× rates applied mid-postemergence. Control of giant foxtail, large crabgrass, and common cocklebur was generally greater with 1× rates mid-postemergence than with 0.5× rates early postemergence. Soybean yields were equivalent with 0.5× and 1× rates. Soybean yields and net income were highest with 1× and 0.5× rates of chlorimuron plus quizalofop and imazethapyr plus clethodim, and metolachlor preemergence (PRE) followed by 0.5× bentazon plus acifluorfen.
Broadleaf Weed Control in Hard Red Spring Wheat (Triticum aestivum) with F8426
Authors: Durgan Beverly R. , Yenish Joseph P. , Daml Ross J. , Miller Douglas W.
Published: March 2018

Studies were conducted at Rosemount and Crookston, MN, in 1994 and 1995 to determine weed control efficacy and crop injury of F8426 (proposed common name carfentrazone-ethyl) in hard red spring wheat. F8426 alone and with 2,4-D or dicamba generally controlled common lambsquarters, kochia, and velvetleaf 90% or more at 0.026 and 0.035 kg/ha. F8426 alone and with 2,4-D or dicamba controlled Pennsylvania smartweed, wild buckwheat, and wild mustard 39 to 100% and was less consistent than control of the aforementioned species. Weed control varied little among the F8426 rates. Weed control was inconsistent between location, year, and species when F8426 was combined with crop oil concentrate, urea–ammonium nitrate solution, and nonionic surfactant. Control was more consistent when 0.28 kg/ha 2,4-D or 0.07 kg/ha dicamba was tank mixed with either F8426 rate. The best control with an F8426 treatment was similar to control from MCPA tank mixed with thifensulfuron plus tribenuron, bromoxynil, or dicamba. Weed control 30 and 45 days after treatment (DAT) was less for F8426-containing treatments than standard treatments, which likely was related to reduced crop competition after severe crop injury. Increasing F8426 rate from 0.026 to 0.035 kg/ha did not greatly increase wheat injury, whereas adding 0.28 kg/ha 2,4-D to either F8426 rate greatly increased crop injury. Wheat yield was reduced up to 63% by F8426 and 2,4-D combinations.
Effects of Tillage and Light Environment on Emergence of 13 Annual Weeds
Authors: Buhler Douglas D.
Published: March 2018

Seeds of many plant species require a brief exposure to light to induce germination. Modifying the light environment during soil tillage may alter weed emergence in agricultural systems. The objective of this research was to evaluate the effect of secondary tillage conducted during daylight and at night on the emergence of 13 summer annual weed species under the same soil and environmental conditions. Annual grass and large-seeded broadleaf species showed little response to light environment during tillage. However, emergence was often less when no tillage was conducted than with any tillage by light environment combination. Emergence of small-seeded broadleaf species often was lower when tillage was conducted during darkness than with tillage during the light. Reductions varied by experiment and species and ranged from 70% for common lambsquarters to less than 30% for Pennsylvania smartweed. Large variations in response also occurred within species.
Sequential Applications Control Woolly Cupgrass (Eriochloa villosa) and Wild-Proso Millet (Panicum miliaceum) in Corn (Zea mays)
Authors: Rabaey Thomas L. , Harvey R. Gordon
Published: March 2018

Field studies were conducted in 1994 and 1995 to determine the contribution of PRE applications of alachlor, metolachlor, acetochlor, SAN 582H, or pendimethalin on woolly cupgrass and wild-proso millet control when followed by POST nicosulfuron at 0, 0.018, 0.027, or 0.036 kg ai/ha. Sequential treatments controlled woolly cupgrass and wild-proso millet greater than single applications of PRE herbicides, which when applied alone resulted in the least wild-proso millet control and lowest corn grain yield. Lack of complete woolly cupgrass control with POST nicosulfuron alone resulted in corn grain yield that was less than with sequential treatments but was equal to PRE treatments. Wild-proso millet control with nicosulfuron at 0.027 kg/ha resulted in corn grain yield that was less than with sequential treatments, but greater than with all PRE treatments except for SAN 582H. All PRE herbicides, regardless of early season performance, when followed by nicosulfuron resulted in woolly cupgrass and wild-proso millet control that was similar. Woolly cupgrass seed production compared to the nontreated check was reduced 98% with acetochlor followed by nicosulfuron. Sequential treatments provided the most consistent woolly cupgrass and wild-proso millet control, the highest corn grain yield, and the greatest reduction in woolly cupgrass and wild-proso millet seed production.
Validation of HERB for Use in Peanut (Arachis hypogaea)
Authors: White Anthony D. , Coble Harold D.
Published: March 2018

Researchers are currently developing predictive weed management models to aid producers in maintaining or improving economic profitability of peanut production while minimizing herbicide inputs and reducing environmental impact. HERB (Version 2.1.P), a computer decision model, has recently been developed for peanut and is now awaiting validation of weed control decisions before being released to the public. Field validation trials in 1994 and 1995 indicate that the current competitive index parameters in the HERB model are invalid, and statistically estimated competitive indices were generated. Estimating new parameters improvedR2values from 0.37 to 0.61. New competitive index parameters allow the HERB model to more accurately predict the level of yield loss at a given weed density.
Venice Mallow (Hibiscus trionum) Seed Production and Persistence in Soil in Colorado
Authors: Westra Philip , Pearson Calvin H. , Ristau Randal , Schweissing Frank
Published: March 2018

This study was conducted to gain insight into the soil seedbank dynamics of Venice mallow in two irrigated Colorado soils. Venice mallow plants produced an average of 3100 seeds per plant under noncompetitive irrigated conditions. Venice mallow seeds collected from three regions of Colorado and stored at 25 C averaged 95% dormancy and less than 4% nonviable seeds 6 mo after harvesting. Percent nonviable seeds in soil remained relatively constant over 2 yr. Most seeds germinated within the first 3 mo after burial in the first crop production year. Seed dormancy decreased to an average of 40% after 3 mo of burial in cultivated soil at Fruita and Rocky Ford, and thereafter remained relatively constant for 21 mo. Fruita seeds underwent lessin situgermination than seeds from Greeley or Rocky Ford. Innate seed dormancy was lower at Fruita (27%) than at Rocky Ford (39%). Enforced dormancy remained constant over a 21-mo period and was similar for both locations (32%). Seeds buried for 2 yr at Fruita underwent greaterin situgermination (42%) than at Rocky Ford (27%). At Fruita, the level of enforced dormancy was higher and the level of innate dormancy lower at the 20-cm than the 2-cm depths. Venice mallow seed dormancy likely is due to an impermeable hard seed coat.
Weed Management Strategies for Conservation-Tillage Sunflower (Helianthus annuus)
Authors: Anderson Randy L. , Lyon Drew J. , Tanaka Don L.
Published: March 2018

We compared applications of trifluralin or ethalfluralin granules incorporated with a sweep plow or pendimethalin (ec) applied without incorporation to incorporating trifluralin (ec) by tandem-disk harrowing for sunflower production. The study was established in winter wheat stubble at three sites in the northern and central Great Plains. Crop residues on the soil surface following sunflower planting was greater than 30% (level required to protect soil from erosion) with all conservation-tillage strategies, but not with disk incorporation. Weed control and sunflower seed yield with conservation-tillage strategies were similar to the disk incorporation practice, demonstrating that producers can use these strategies for sunflower production and to protect soil from erosion.
Olive (Olea europea) Jift Suppresses Broomrape (Orobanchespp.) Infections in Faba Bean (Vicia faba), Pea (Pisum sativum), and Tomato (Lycopersicon esculentum)
Authors: Ghosheh Hani Z. , Hameed Khalid M. , Turk Munir A. , Al-Jamali Abbas F.
Published: March 2018

Olive jift is a solid by-product of olive (Olea europea) oil processing. Greenhouse experiments were conducted to evaluate olive jift effect on broomrape (Orobanchespp.) infections on three crops. Soil—jift mixtures were used as potting medium in ratios of 1:0, 1:1, and 3:1 soil to jift. Broomrape seeds were evenly incorporated in the potting media at 0, 150, 300, 450, 600, 750, and 900 seeds/kg. Pots planted with faba bean or pea were inoculated with seeds ofO. crenataForsk., whereas pots planted with tomato were inoculated with seeds ofO. lavandulaceaReichenb. Jift in soil reduced broomrape germination and infection on all three hosts regardless of inoculation densities. Pea was not infected with broomrape in jift-containing media at any inoculation density, whereas only sporadic broomrape infections were observed in faba bean and tomato grown in jift-mixed soils. Fresh and dry weights of all crops were not adversely affected by mixing jift with soil. These results suggest a possible use of jift as an inexpensive organic material for broomrape control.