bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity of Nicosulfuron, Rimsulfuron, and Their Mixture on Field Corn (Zea mays). Soybean (Glycine max), and Seven Weed Species
Authors: Mekki Mounir , Leroux Gilles D.
Published: March 2018

Seven annual weed species were treated under greenhouse conditions with six rates of either nicosulfuron, rimsulfuron, or a 1:1 mixture (DPX-79406). Herbicide rates in g ai/ha producing 90% dry biomass reduction (GR90) were calculated for each weed species. Accordingly, weeds were classified as very susceptible when GR90≤ 9, susceptible when 9 < GR90 ≤ 18, moderately susceptible when 18 < GR90≤ 27, and tolerant when, GR90> 27. Giant and green foxtails were very susceptible to the three herbicides. Proso millet was very susceptible to rimsulfuron and DPX-79406, and susceptible to nicosulfuron. Wild oat was susceptible to nicosulfuron and DPX-79406, and moderately susceptible to rimsulfuron. Redroot pigweed was very susceptible to nicosulfuron; whereas, it was susceptible to rimsulfuron and DPX-79406. Common ragweed and smooth crabgrass were tolerant to the three herbicides. In a second experiment, we used regression estimate analysis with an additive reference model to evaluate nicosulfuron and rimsulfuron interaction on corn, soybean, common ragweed, and smooth crabgrass. We found these herbicides synergistic on smooth crabgrass, antagonistic on soybean, less than additive on common ragweed, and additive on corn.
Effect of Tillage and Glyphosate on Control of Quackgrass (Elytrigia repens)
Authors: Chandler Kevin , Murphy Stephen D. , Swanton Clarence J.
Published: March 2018

Field studies were conducted during two soybean-corn rotations to evaluate the effect of tillage systems on quackgrass growth and control with and without glyphosate. In the final year of the study, tillage alone (compared to no-till) resulted in 88%, 78%, 64%, and 31% control of quackgrass with fall moldboard plow, spring moldboard plow, fall soil-saver, and spring soil-saver tillage, respectively. When glyphosate was used to control quackgrass, crop yields increased as tillage was reduced and excellent control of quackgrass in no-till was achieved. Increased shoot growth (in moldboard plowed and fall soil-saver tillage plots), exposure of rhizomes in winter (in fall tilled plots), and increased depth of rhizome burial (in spring tilled plots) increased quackgrass control. In general, the total biomass of quackgrass was reduced in drier years. Nonetheless, drought increased crop yield losses caused by quackgrass interference.
Weed Control Economics in Bell Pepper (Capsicum annuum) with Napropamide and Hand Weeding
Authors: Lanini W. Thomas , Le Strange Michelle
Published: March 2018

Field studies were conducted in 1990 and 1991 at Davis and Five Points, CA to evaluate weed control with napropamide and hand-weeding and the effect on yield and profitability in transplanted bell pepper. Weed cover 8 wk after transplanting averaged less than 10% in plots hand-weeded biweekly for 6 wk after transplanting. Weed cover at harvest was less than 30% in plots hand-weeded at 8 wk after transplanting. Napropamide treatment reduced weed cover at 8 wk after transplanting an average of 34% compared to untreated plots, but differences declined to 14% at harvest. Time required to hand-weed plots was greater if the interval between weeding was 4 instead of 2 wk. The time needed to hand-weed plots was reduced from 38% to 71% by napropamide treatment. When weeds were excluded by hand-weeding for the entire season, bell pepper yielded 25 810 kg/ha and was 4% to 18% higher than other treatments. Net returns were greater for plots that were hand-weeded the entire season or when napropamide was combined with hand-weeding at 4 and 8 wk after transplanting, compared to other treatments.
Common St. Johnswort
Authors: Mitich Larry W.
Published: March 2018

Worldwide, 10 genera and 400 species comprise the Hypericaceae, the St. Johnswort Family. The genus Hypericum, with 350 of these species (11), includes evergreen or deciduous shrubs, subshrubs, and herbaceous perennials. The hypericums have simple, opposite or whorled leaves and usually golden-yellow many-stamened flowers.

Common St. Johnswort (Hypericum perforatum L.) is a hairless perennial, reproducing by seeds and by runners from the base of the stem. It grows 20 to 100 cm tall, with spreading branches and small deep green glabrous oblong-ovate leaves, perforated by many translucent glandular dots. Branched clusters of golden yellow flowers with tiny black spots are produced from May to August (14).
Mow-kill Regulation of Winter Cereals for Spring No-till Crop Production
Authors: Wilkins Erik D. , Bellinder Robin R.
Published: March 2018

Field studies determined the influence of developmental stage on mow-killing of winter wheat and rye. Both crops were clipped at either three or four different growth stages in 1992 and 1993. When mowed at first node, wheat biomass was 4350 and 1970 kg/ha in 1992 and 1993, respectively. At this stage, primary tiller apices were below 10 cm and regrowth was vigorous. Mowing prior to 75% heading consistently yielded more than 1000 kg/ha regrowth 8 wk later. Wheat cut after flowering produced 15 460 and 9160 kg/ha dry matter in 1992 and 1993, respectively, but less than 30 kg/ha total regrowth. At first and second node, rye produced 4440 and 1800 kg/ha biomass in 1992 and 1993. When mowed belore boot, more than 50% of the total rye biomass was due to regrowth. Rye mowed at boot yielded 6940 and 3740 kg/ha in 1992 and 1993 respectively, and regrowth measured 780 and 910 kg/ha 8 wk later. Mowing after flowering resulted in no measurable regrowth. Soil temperature and PAR were affected by mow-kill date and biomass. Biomass at first mowings (first and second node) in both wheat and rye reduced seasonal soil temperatures 3.5 C compared to bare soil temperatures; while biomass at kernal-filling lowered temperatures 6.0 C. Measured 8 wk after mowing, first node mowings absorbed between 55% and 70% PAR, while plants mowed at kernal-filling absorbed less than 5%.
Metabolites fromPseudomonas fluorescensStrain D7 Inhibit Downy Brome (Bromus tectorum) Seedling Growth
Authors: Gealy David R. , Gurusiddaiah S. , Ogg Alex G. , Kennedy Ann C.
Published: March 2018

Phytotoxins produced by the naturally-occurring rhizobacterium,Pseudomonas fluorescensstrain D7 (strain D7), in shake cultures from several media sources adversely affected downy brome at several growth stages and affected seeds, whole plants, and isolated cells. These uncharacterized phytotoxins inhibited root and shoot growth of downy brome by 80% in a seed germination agar assay at 2 and 400 ng total solids/ml, respectively. In a hydroponics assay, downy brome and winter wheat dry weights were reduced 50% by cell-free broth concentrations of 15 and 26% of the initial broth concentration, respectively, indicating an almost 2x selectivity between winter wheat and downy brome. Plant water use was reduced similarly. Plasma membranes of isolated protoplasts of downy brome were damaged within 2 h by diluted cell-free broth. Cold-precipitated phytotoxins of strain D7 produced in semi-synthetic and synthetic media reduced dry weight of downy brome seedlings by 100 and 89%, respectively, and killed plants rapidly.
Selecting Cost-Minimizing Herbicide Programs for Corn (Zea mays)
Authors: Olsen J. Rolf , Harper Jayson K. , Curran William S.
Published: March 2018

A computer model which selects least cost herbicide programs given a minimum desired level of weed control could provide growers with economical weed management options. Using an integer programming approach, a herbicide selection model was developed for corn production under Pennsylvania conditions. Models for three rotations (corn-soybean, corn-corn, and corn-alfalfa) under three tillage systems (conventional tillage, reduced tillage, and no-till) that evaluated 21 soil-applied and 13 postemergence herbicide options for 24 weeds were developed. Each model minimizes the cost of a herbicide program subject to a desired level of weed control. By selecting the weed species to be controlled and the level of control desired, customized herbicide programs can be generated. The models can also be used to evaluate the cost of changing the level of control desired for an individual weed species or set of weeds.
Shattercane (Sorghum bicolor) Biotype Variation in Tolerance to Primisulfuron
Authors: Sabatka Ronald G. , Roeth Fred W. , Martin Alex R. , Mortensen David A.
Published: March 2018

Shattercane accessions were collected from 33 corn fields previously treated with nicosulfuron or primisulfuron. In a greenhouse study, we found no resistance to primisulfuron among the accessions. However, 15% of the accessions were more tolerant to primisulfuron than the most susceptible accessions. Shattercane survival among the 33 accessions ranged from 0 to 39% at 40 g ai/ha. While most accessions emerged uniformly, 26% of the accessions had 5 to 38% emergence after primisulfuron treatment. Delayed emergence could facilitate herbicide avoidance.
Composition and Diversity of Plant and Small Mammal Communities in Tebuthiuron-Treated Big Sagebrush (Artemisia tridentata)
Authors: Johnson Kris H. , Olson Richard A. , Whitson Thomas D.
Published: March 2018

Sagebrush control has historically involved mechanical and chemical (2,4-D) treatments designed for total control and which detrimentally affect nontarget plant species, resulting in decreases in native wildlife abundance and diversity. Tebuthiuron, a potentially selective herbicide with thinning capabilities, was applied at various rates to big sagebrush plots near Ten Sleep, WY in 1979 and Hyatteville, WY in 1983. Plant and small mammal communities were evaluated in 1992 and 1993. Big sagebrush cover in untreated areas was 31 ± 1% in 1992 and 34 ± 1% in 1993 at Ten Sleep, and 44 ± 4% at Hyatteville (α = 0.10). Big sagebrush control increased as application rate increased. Productivity of herbaceous species (graminoids, forbs, or both) tended to be greatest at about 11 to 17% big sagebrush cover. In general, plant community diversity tended to be greatest where sagebrush was thinned to this level. Small mammal community diversity was least at both sites where big sagebrush cover was less than 5%, and was strongly correlated with plant community diversity at Ten Sleep (R2W= 0.99; 4 degrees of freedom). In addition, greater abundance of or better habitat quality for endemic, stenotypic (habitat specialist) species was associated with about 15% big sagebrush cover. This suggests (albeit retroductively) that biodiversity at both local (alpha) and global (epsilon) scales might be conserved by thinning big sagebrush with tebuthiuron.
Managing for Mature Habitat in Production Forests of Western Oregon and Washington
Authors: Cole Elizabeth C.
Published: March 2018

Standard timber management practices in the Pacific Northwest result in stands which often vary from unmanaged stands in structure and composition. Forest and wildlife managers have identified a deficit of stands in the mature (> 100-yr-old) age class that contain certain desirable wildlife habitat features. Techniques are being developed that would increase the likelihood that managed stands can produce these characteristics. The key desirable components in these stands include large (> 75 cm diam breast height) conifer trees, snags, coarse woody debris, and understory structure, including regeneration. Vegetation management techniques can facilitate development of these components within stands. Thinning the overstory, underplanting shade-tolerant species, and creating snags and coarse woody debris can be accomplished within a production forest. Maintaining shade-intolerant species requires a higher level of disturbance and canopy opening than needed for shade-tolerant species. Treatments which remove competition from shrubs and herbaceous plants may be necessary to insure growth and survival of understory regeneration. Injection of different herbicides into low-grade conifers may yield different types of snags in comparison to girdling or topping. Although much of the understory may be eliminated during future thinnings and final harvest, some of the structure will remain and could be carried over into the next rotation along with snags and large coarse woody debris. These treatments are expected to enhance mature habitats in present and future cycles with minimum impact on yield.
Influence of Glyphosate on Vegetation Dynamics in Different Successional Stages of Sub-Boreal Spruce Forest
Authors: Sullivan Thomas P. , Lautenschlager R. A. , Wagner Robert G.
Published: March 2018

This study was designed to evaluate changes in plant biomass, species richness, and diversity after application of glyphosate herbicide in several successional stages of sub-boreal spruce forest near Prince George, British Columbia, Canada. Vegetation was sampled in replicate control (reference) and treatment blocks of “herb,” “shrub,” and “shrub-tree” stages of cutover forest habitats. Volume of herb layers declined temporarily in the first post-treatment year. Shrub layers were reduced in herb and shrub stages, and shrubs and trees were reduced temporarily in the shrub-tree stage. Species richness of herbs and shrubs was similar in control and treatment blocks in the herb successional stage, but shrub richness declined on the treatment in the shrub stage. There were no consistent differences in numbers of herb, shrub, or tree species between control and treatment blocks in the shrub-tree stage. Species diversity (Simpson's index and Shannon-Wiener function) of herbaceous plants was not affected by herbicide application in any of the successional stages, but diversity of shrubs was lower in treatment than control blocks in the herb and shrub stages. Diversity of trees was reduced on treatment blocks in the shrub-tree stage. Species abundance curves of overall plant communities showed little change in the herb stage, a decline in the first post-treatment year in the shrub and shrub-tree stages, with similar patterns between control and treatment blocks in subsequent post-treatment years. The general lack of community-wide reductions in plant biomass and diversity, and the short-term duration of specific changes, suggest that conifer release treatments of plantations have no substantial, incremental effects on wildlife habitat.
Efficacy of Rimsulfuron and Metribuzin in Potato (Solanum tuberosum)
Authors: Ackley John A. , Wilson Henry P. , Hines Thomas E.
Published: March 2018

In 1992 and 1993, rimsulfuron alone at 17, 35, and 70 g ai/ha, and at 35 g/ha plus metribuzin at 280 g ai/ha, respectively, was evaluated PRE and POST for weed control in potato. Rimsulfuron at 35 g/ha PRE and POST controlled common lambsquarters and giant foxtail and when combined with 280 g/ha metribuzin, controlled common ragweed and jimsonweed. Rimsulfuron and rimsulfuron with metribuzin caused slight to moderate chlorosis in new terminal growth of potato but chlorosis disappeared within 3 wk. Potato height, tuber yields, and tuber quality were not affected by rimsulfuron alone or with metribuzin.
Sulfonylurea Herbicides Affect Hard Red Winter Wheat (Triticum aestivum) Forage and Grain Yield
Authors: Koscelny Jeffrey A. , Peeper Thomas F. , Krenzer Eugene G.
Published: March 2018

Field experiments were conducted to determine whether residual sulfonylurea herbicides applied at cheat suppression rates affect hard red winter wheat forage production and grain yield. Triasulfuron at 30 g/ha or chlorsulfuron plus metsulfuron at 26 g/ha applied PRE and metribuzin applied early POST alone at 280 g/ha or tank-mixed with triasulfuron at 158 + 30 g/ha or chlorsulfuron plus metsulfuron at 210 + 21 g/ha, all decreased total forage production of weed-free wheat. Conversely, all herbicide treatments except triasulfuron applied PRE increased wheat grain yield.
Influence of Flame Cultivation on Mortality of Cotton (Gossypium hirsutum) Pests and Beneficial Insects
Authors: Seifert Simone , Snipes Charles E.
Published: March 2018

Field studies to determine the effect of flame cultivation on cotton pests and beneficial insects were conducted in 1994. Mortality of caged tarnished plant bugs and convergent lady beetles located at the soil surface and canopy heights of 10 and 20 cm above the ground in 25- to 30-cm cotton was recorded after flaming at two liquid propane-gas (LP-gas) pressure settings with or without water-shield protection. Air temperatures, measured proximal to insects during flame treatments, were lower at higher levels in the cotton canopy regardless of LP-gas pressure and the presence or absence of water-shield protection. A mortality of 100% was observed at the soil surface for both insect species in all treatments. Plant bug and lady beetle mortality was lower at the 10- and 20-cm heights relative to soil surface values after flaming at 100 kPa LP-gas pressure. After treatments at 175 kPa, only the mortality of lady beetles at 20 cm above the ground was lower than mortality obtained at the soil surface and 10-cm height. Although flaming induced lady beetle mortality, these beneficial insects were not affected to the same extent as plant bugs at higher canopy levels.
Impact of Herbicides Applied Annually for Twenty-three Years in a Deciduous Orchard
Authors: Foy Chester L. , Drake Charles R. , Pirkey Carlton L.
Published: March 2018

A semi- and high-density apple and peach orchard was established at Blacksburg, VA. Starting 1 yr after transplanting, tree rows were treated with paraquat, 2,4-D, or amitrole plus simazine for 4 yr. Thereafter, diuron, simazine, or terbacil was applied in conjunction with paraquat or glyphosate. During the 12th growing season, young trees planted between existing trees failed to make proper growth. Oat bioassay of soils collected from treated rows revealed that the tree row topsoil (0 to 7.5 cm) produced less oat biomass than did deeper row soils (to 30 cm) or soils of corresponding depths from adjacent non-treated tall fescue sod alleyways. Poor growth of trees may have been related to other factors (competition from older trees, drought conditions, etc.) since herbicide residues in the upper 7.5 cm would have little effect on tree roots below this depth. After 3 yr the trees developed normally. Tree rows became heavily infested with weeds 1 yr following cessation of 23 yr of consecutive herbicide treatments.
Noxious Weed Survey: Awareness and Attitudes in Montana
Authors: Sheley Roger L. , Jacobs James S. , Floyd Joe W.
Published: March 2018

A telephone survey of Montana residents was undertaken to determine their knowledge of noxious weeds, their attitudes toward noxious weeds, how they use the outdoors with respect to spreading noxious weeds, and the best methods to distribute information to those most unaware about noxious weeds. Most Montanans (76%) thought that noxious weeds were a serious or very serious problem. Respondents from central (67%) and southwestern (59%) Montana were more likely to evaluate the noxious weed problem as serious than respondents from western (37%) or southeastern (33%) Montana. Most Montanans (80%) could name a problem associated with noxious weed invasion. Farmers and operators of non-farm machinery knew more problems associated with weeds than people not involved in these activities. Respondents knew ways weeds spread (89%) but many could not think of ways to prevent weed spread (70%) or identify activities they participate in that might spread weeds (64%). Television (89%) and newspaper stories (85%) were mentioned most often as the most effective ways to distribute information about noxious weeds.
Fermentation Strategies for Improving the Fitness of a Bioherbicide
Authors: Jackson Mark A. , Schisler David A. , Slininger Patricia J. , Boyette C. Douglas , Silman Robert W. , Bothast Rodney J.
Published: March 2018

The commercial development of microbial bioherbicides requires the availability of low-cost production methods. The use of liquid culture fermentation is generally considered necessary to achieve this goal. Our strategy for optimizing liquid culture media is based on using defined nutritional conditions. Specific changes are made in the nutritional environment of the medium and the effect of these changes is assessed in terms of propagule yield, efficacy, and stability of the bioherbicidal agent. Liquid culture studies with the fungusColletotrichum truncatumhave demonstrated that nutrition impacts not only spore yield but also spore efficacy in controlling the weed hemp sesbania. Nutritional conditions were identified which suppressed sporulation and promoted the production of high concentrations ofC. truncatummicrosclerotia in liquid culture. Microsclerotia ofC. truncatum(particle size range = 180 μm to 425 μm) showed promise as bioherbicidal propagules due to their stability as a dry preparation and their efficacy in controlling hemp sesbania when used as a soil amendment. By understanding how nutrition impacts propagule formation, yield, efficacy, and stability, rational approaches can be taken to develop submerged culture production methods for microbial biocontrol agents. Breakthroughs in these areas should allow numerous promising bioherbicidal agents to become commercial products.
Postemergence Broadleaf Weed Control in Corn (Zea mays) with CGA-152005
Authors: Obermeier Michelle R. , Kapusta George
Published: March 2018

Field studies were conducted in 1993 and 1994 to evaluate broadleaf weed control in corn with the sulfonylurea herbicide CGA-152005, CGA-152005 was applied at 10 to 50 g ai/ha alone and in combination with 2,4-D, dicamba, or atrazine. No corn injury was observed either year. Metolachlor plus CGA-152005 controlled redroot pigweed, velvetleaf, and common cocklebur 95% or more in 1993 and 1994. Common lambsquarters and ivyleaf morningglory control was dependent on CGA-152005 rate, weed size at application, and growing conditions. In 1994, control of velvetleaf and ivyleaf morningglory with CGA-152005 at 10 or 20 g/ha was less when applied as a tank-mix with atrazine and dicamba compared with when it was applied alone, probably due to antagonism caused by the companion herbicide. Generally, corn yield was related to weed control.
Late Season Weed Suppression from Dry Bean (Phaseolus vulgaris) Cultivars
Authors: Urwin Carl P. , Wilson Robert G. , Mortensen Dave A.
Published: March 2018

Dry bean cultivars were evaluated for suppression of late-season weed emergence near Scottsbluff, NE in 1993 and 1994. The 12 cultivars differed in plant canopy architecture and the amount of light intercepted. In 1993, the vine growth habit of Pinto ‘D-84354’ provided a more dense canopy and more yellow foxtail suppression than Pinto ‘RS-101’ that had an upright growth habit. Growing season also influenced plant canopy and late season weed emergence. Cooler temperatures in 1993 resulted in a less dense Navy ‘Mayflower’ canopy which provided less redroot pigweed suppression than warmer conditions in 1994 that resulted in a more dense crop canopy. No difference in weed suppression was observed among cultivars for common lambsquarters, common purslane, and hairy nightshade.
Factors Affecting Eclipta (Eclipta prostrata) Seed Germination
Authors: Altom John V. , Murray Don S.
Published: March 2018

Controlled environmental chamber experiments were conducted for a 14-d incubation period to measure the effect of temperature, light, light intensity, water potential, and pH on eclipta seed germination. In full light, seed germinated over a range of 10 to 35 C; however, germination was highest at 83% at 35 C. Seeds were strongly photoblastic with none germinating in the dark. Seeds germinated in light intensities between 6 and 100% of full light. Seeds germinated 78 to 88% in water potentials of 0.0, −0.1, and −0.2 MPa. In distilled water (pH ∼ 5.5) and a buffered solution pH 6 and 7, seeds germinated 85 to 89%; however, some seeds germinated in a buffered solution pH range of 5 to 8. After the first 14-d incubation period, ungerminated seeds were transferred to distilled water and incubated at 35 C in full light for 4 to 6 d as a second incubation period. Seeds germinated 89 to 96% after this second incubation period when first incubation was at temperatures 10 to 35 C in full light or darkness, light intensities 0 to 100% of full light, water potentials 0.0 to −0.8 MPa, and buffered solution pH levels of 5.5 to 7.
Environmental Effects on MSMA Phytotoxicity to Wild-Type and Arsenical Herbicide-Resistant Common Cocklebur (Xanthium strumarium)
Authors: Nimbal Chandrashekhar I. , Shaw David R. , Wills Gene D. , Duke Stephen O.
Published: March 2018

Effects of temperature, relative humidity, and light on MSMA phytotoxicity to wild-type and arsenical herbicide-resistant biotypes of common cocklebur grown from seed collected in Mississippi were evaluated. In growth chamber studies, 20-d-old plants were sprayed with 0.5 kg ai/ha of MSMA, and after 7 d, fresh weight and chlorophyll content were measured to estimate phytotoxicity. All three environmental factors influenced the level of weed resistance. In studies with day/night temperatures of 30/25 C and 500 μmol/m2/s PPFD light with a 14-h photoperiod, phytotoxicity of MSMA at 40% relative humidity was minimal, but was significantly greater at 60 and 90% relative humidities. The resistant (R) biotype was affected less than the susceptible (S) biotype at the higher relative humidities. The level of resistance estimated by fresh weight reduction was greatest at 30/25 C, but was most pronounced at 35/30 C using chlorophyll measurements. Resistance was lowest at 25/20 C by either measurement. MSMA phytotoxicity occurred at light intensities of 75, 500, and 750 μmol/m2/s PPFD; however, biotypic response was greatest at 500, followed by 750 μmol/m2/s PPFD. Resistance of the (R) biotype to MSMA was not significant at 75 μmol/m2/s, suggesting that differentiation between the biotypes for MSMA sensitivity would be difficult under low light.
Smooth Pigweed (Amaranthus hybridus) and Livid Amaranth (A. lividus) Response to Several Imidazolinone and Sulfonylurea Herbicides
Authors: Manley Brian S. , Wilson Henry P. , Hines Thomas E.
Published: March 2018

The effects of chlorimuron, imazaquin, imazethapyr, nicosulfuron, primisulfuron, and thifensulfuron were evaluated on a population of smooth pigweed in Painter, VA with no history of treatment with acetolactate synthase (ALS)-inhibitor herbicides. Imazethapyr and nicosulfuron gave the greatest smooth pigweed control, and subsequently were used in field and greenhouse studies to investigate susceptibility of smooth pigweed and livid amaranth populations to ALS-inhibitor herbicides. Approximately 5 million smooth pigweed plants from Painter were treated with imazethapyr or nicosulfuron from 1992 to 1994 and no ALS-inhibitor-resistant plants were identified. In the greenhouse, the response of smooth pigweed from Painter, VA, Marion, MD, and Oak Hall, VA and livid amaranth from Warren County, NJ to imazaquin or imazethapyr and nicosulfuron was investigated. Smooth pigweed from Marion and Oak Hall and livid amaranth from NJ had histories of treatment with ALS-inhibitors. Painter smooth pigweed control was 81 to 97% by imazethapyr and nicosulfuron while control of the Marion and Oak Hall populations was 3 and 18% by imazaquin at 560 and 1120 g ai/ha, respectively, and control by nicosulfuron at 35 g ai/ha was 50 to 73%. Control of livid amaranth from Warren County, NJ was 8 to 15% by imazethapyr at 560 g ai/ha, and was 30 to 58% by nicosulfuron at 35 g/ha.
Effect of Bensulfuron-Methyl on Cotton (Gossypium hirsutumL.) Growth and Development
Authors: Monks C. Dale , Patterson Michael G. , Pegues Malcolm
Published: March 2018

Field experiments were conducted in Alabama from 1992 through 1994 to evaluate the potential of the methyl ester of bensulfuron applied at sublethal rates as a plant growth regulator for reducing plant height and boll rot in cotton. Bensulfuron at 0.017 and 0.034 g ai/ha or mepiquat chloride at 10 g ai/ha was applied POST alone at the pinhead square or early-bloom stage of cotton growth or sequentially at 0.017 followed by (fb) 0.017 g/ha, 0.034 fb 0.034 g/ha of bensulfuron and 5 fb 5, 10 fb 10, 10 fb 20, or 20 fb 20 g/ha of mepiquat chloride. Mepiquat chloride had no effect on yield in 1992 and 1994 but decreased yield when applied sequentially in 1993. Bensulfuron was generally detrimental to first position fruit retention, and it delayed maturity. Treatments that reduced plant height did not reduce boll rot. Bensulfuron treatments that reduced plant height also reduced yield; therefore, the potential for its use as a growth regulator in cotton appears limited.
Identification of Sulfometuron-Resistant Italian Ryegrass (Lolium multiflorum) Selections
Authors: Taylor James M. , Coats G. Euel
Published: March 2018

Two sulfometuron-resistant biotypes of Italian ryegrass were identified from rights-of-way of U.S. Highway 49E in Holmes County, MS, and State Highway 14 in Humphreys County, MS. Sulfometuron at 5.2 g ai/ha applied PRE or POST reduced shoot fresh weight of these selections 20% or less at 4 wk after treatment. A susceptible ‘Gulf’ Italian ryegrass was reduced 52% or more in shoot fresh weight by 0.5 g/ha sulfometuron applied PRE or POST The biotype from Highway 49E was reduced 47% or less in shoot fresh weight by 520 g/ha sulfometuron applied PRE or POST.
Wine Grape (Vitis vinifera) Response to Repeated Exposure of Selected Sulfonylurea Herbicides and 2,4-D
Authors: Bhatti Muhammad A. , Al-Khatib Kassim , Parker Robert
Published: March 2018

‘Lemberger’ wine grape response was evaluated when chlorsulfuron, tribenuron, thifensulfuron, chlorsulfuron plus metsulfuron, thifensulfuron plus tribenuron, and 2,4-D were applied up to three times at weekly intervals in 1992 and 1993 at rates simulating drift. All herbicides injured grapevines visibly. Symptoms increased and total leaf area and grape pruning weight decreased as the herbicide rate and number of applications increased. Grapevines generally recovered within 45 to 60 d from symptoms caused by single exposures to low levels of sulfonylurea herbicides. Multiple exposures of grapevines to 2,4-D, tribenuron, and chlorsulfuron plus metsulfuron at 1/100 of the maximum use rate for wheat caused the greatest injury, which persisted throughout the entire growing season and reduced pruning weight. Based on potential use rate, the order of herbicide phytotoxicity was 2,4-D > tribenuron > chlorsulfuron plus metsulfuron > thifensulfuron plus tribenuron > chlorsulfuron > thifensulfuron. Rates that slightly injured grapevines did not reduce growth as measured by pruning weight. However, multiple exposure to high rates of 2,4-D, tribenuron, and chlorsulfuron plus metsulfuron adversely affected growth.
The Environmental Protection Agency's Programs to Encourage the Use of Safer Pesticides
Authors: Andersen Janet , Leslie Anne , Matten Sharlene , Kumar Rita
Published: March 2018

The Office of Pesticide Programs (OPP) within the United States Environmental Protection Agency (EPA) has initiated several programs to reduce risks associated with the use of pesticides. Examples include accelerated registration of new products (including biological pesticides) that offer reduced risk to human health and the environment, and regulatory relief for products posing virtually no risk to provide replacement for more problematic pesticides. In addition, efforts are being undertaken to reduce pesticide resistance in target pests, develop joint “Environmental Stewardship” efforts between the EPA, United States Department of Agriculture (USDA), and the United States Food and Drug Administration (FDA). The new Biopesticides and Pollution Prevention Division (BPPD), established as a pilot in October 1994, has responsibility for many above functions, with special emphasis on registration of biological pesticides and development of the new Pesticide Environmental Stewardship Program (PESP). This program is designed to recognize achievements already made by farmers to reduce conventional pesticide use and to find further improvements through cooperative efforts with growers.
Influence of Adjuvants on Hemp Sesbania (Sesbania exaltata) Control by Chlorimuron
Authors: Jordan David L. , Burns Ann B.
Published: March 2018

Hemp sesbania control by chlorimuron applied with crop oil concentrate at 1.0% v/v, BCH 815 at 1.0% v/v, methylated seed oil at 1.0% v/v, a blend of methylated seed oil and organosilicone surfactant at 0.5% v/v, organosilicone-based surfactant at 0.125% v/v, and nonionic surfactant at 0.25% v/v was evaluated in field studies in 1994 and 1995. Control by chlorimuron at 4.5 g ae/ha was greater when applied with BCH 815, organosilicone-based surfactant, and nonionic surfactant than with crop oil concentrate, methylated seed oil, and a blend of methylated seed oil and organosilicone surfactant. When chlorimuron was applied at 4.5 g/ha with BCH 815 or nonionic surfactant, hemp sesbania control was similar to that by chlorimuron at 9 g/ha applied with methylated seed oil, the blend of methylated seed oil and organosilicone surfactant, or organosilicone-based surfactant.
Adjuvant Combinations with Quizalofop for Wild Oat (Avena fatua) Control in Peppermint (Mentha piperita)
Authors: Stougaard Robert N.
Published: March 2018

Field experiments were conducted at Kalispell, MT, to determine the optimum adjuvant combination for wild oat control in peppermint with quizalofop. Quizalofop was applied to four- and eight-leaf wild oat plants at 20 and 50 g ai/ha with either a nonionic surfactant (NIS) or methylated seed oil (MSO) alone or in combination with 28% urea ammonium nitrate (UAN) liquid fertilizer. Differences among adjuvants were most apparent when quizalofop was applied at the lowest rate. MSO was more effective than NIS for enhancing quizalofop activity. Quizalofop efficacy with both adjuvants increased when applied with UAN. Greater than 90% wild oat control was obtained with the lowest rate when applied with MSO plus UAN to four-leaf wild oat plants. These results demonstrate the potential to improve the consistency of weed control as well as reduce postemergence herbicide rates when applied with the proper adjuvant combination.
Influence of Broadleaf Weeds on Chlorothalonil Deposition, Foliar Disease Incidence, and Peanut (Arachis hypogaea) Yield
Authors: Royal Stanley S. , Brecke Barry J. , Shokes Frederick M. , Colvin Daniel L.
Published: March 2018

Field experiments were conducted at Jay and Marianna, FL in 1988 and 1989 to determine the effects of sicklepod, Florida beggarweed, and common cocklebur density on chlorothalonil deposition to peanut foliage, peanut foliar disease incidence, and peanut yield. At a density of four weed plants per 8 m of row, Florida beggarweed and sicklepod reduced chlorothalonil deposition on peanut foliage by 20%, while common cocklebur reduced fungicide deposition by 34%. At the same density, incidence of the foliar diseases early leaf spot and late leaf spot increased 10% with Florida beggarweed, 14% with sicklepod, and 20% with common cocklebur compared with weed-free peanut. The predicted peanut yield loss from a weed density of four plants per 8 m was 16 to 19% for Florida beggarweed, 23 to 25% for sicklepod, and 31 to 39% for common cocklebur. Weed biomass increased with increasing weed density.
Evaluation of Fungus-Chemical Compatibility for Melaleuca (Melaleuca quinquenervia) Control
Authors: Rayachhetry Min B. , Elliott M. L.
Published: March 2018

Integration of a fungal pathogen with herbicides may enhance melaleuca control efforts in South Florida. Hyphal inoculum of fourBotryosphaeria ribisGross & Duggar isolates were evaluated in vitro for compatibility with imazapyr, glyphosate, and a surfactant. Imazapyr at 12 to 60 mg ai/ml did not cause significant loss of inoculum viability in all four isolates within 2 h after mixing. After 24 h, inoculum viability of isolate BR-4 remained unchanged at these imazapyr concentrations, but viability of BR-1 through BR-3 was reduced. Glyphosate at the lowest concentration (32 mg ai/ml) significantly reduced inoculum viability of all isolates within 2 h. Initially, the inoculum viability of all isolates remained unaffected by 1, 5, and 10% (v/v) surfactant concentrations. After 24 h, the surfactant reduced inoculum viability of BR-2, BR-3, and BR-4 inconsistently between experiments, while the inoculum viability of BR-1 was reduced significantly at all concentrations. Mixing of the lowest concentrations of imazapyr, glyphosate, and surfactant significantly reduced inoculum viability within 2 h. This corresponded to the results obtained for glyphosate alone. These results show that hyphal inoculum ofB. ribismay be mixed with imazapyr and surfactant for field applications, but mixing the fungus with glyphosate may not be as efficacious.
Influence of Herbicide Combinations and Application Technology on Cogongrass (Imperata cylindrica) Control
Authors: Willard Thomas R. , Gaffney James F. , Shilling Donn G.
Published: March 2018

Field experiments were conducted to evaluate various herbicides and application technologies for the control of cogongrass. Imazapyr at 0.8 kg ae/ha provided the highest cogongrass control, followed by glyphosate (3.4 kg ae/ha) and sulfometuron (1.1 kg ai/ha) when applied as a single application. When sequential applications were evaluated, glyphosate plus imazapyr provided the best control. Sulfometuron could be applied sequentially after imazapyr or glyphosate with no loss of control, but control was less if sulfometuron was the initial herbicide. Tank mix combinations of glyphosate and imazapyr (100% rate at 3.4 and 1.1 kg ae/ha, and subsequent rates of 0 + 100, 25 + 75, 50 + 50, 75 + 25, and 100 + 0% of each herbicide, respectively) provided similar cogongrass control regardless of rate. Control using imazapyr improved from 20 to 40% with 234 L/ha diluent volume when compared to 46 L/ha. Glyphosate at either of these volumes provided from 0 to 21% inhibition of cogongrass. A 50% concentration of imazapyr applied twice with a ropewick provided greater control than a 33% concentration with one pass or either concentration of glyphosate with one or two passes. Efficacy with glyphosate applied using a ropewick was not affected by concentration or number of passes.
Response of Transplanted Watermelon (Citrullus lanatus) to Ethalfluralin Applied PPI, PRE, and POST
Authors: Mitchem Wayne E. , Monks David W. , Mills Robert J.
Published: March 2018

Field experiments conducted in 1992 and 1993 evaluated transplanted watermelon tolerance to ethalfluralin applied PPI, PRE (before transplanting), and POST (immediately after transplanting) at 1.2 or 2.4 kg ai/ha. Other treatments for comparison included the registered herbicides ethalfluralin POST-directed spray (PDS), ethalfluralin PDS followed by (fb) naptalam POST, bensulide plus naptalam PPI, and a nontreated check. All treatments controlled common lambsquarters and goosegrass 83 to 100% 2 and 6 weeks after treatment (WAT). Watermelon was injured 30 to 77% in 1992 and 14 to 83% in 1993 by ethalfluralin PPI or PRE at 1.2 or 2.4 kg/ha. Ethalfluralin POST was not injurious to watermelon. In 1992, watermelon treated with ethalfluralin POST at 1.2 and 2.4 kg/ha yielded 52 to 62% more fruit than watermelon from the nontreated check. In 1993, yield of transplanted watermelon treated with ethalfluralin POST was similar to that in the nontreated check.
Preemergence and Postemergence Herbicides for Large Crabgrass (Digitaria sanguinalis) Control in Centipedegrass (Eremochloa ophiuroides)
Authors: Johnson B. Jack
Published: March 2018

Two experiments were conducted over a two-year period for large crabgrass control in centipedegrass. The experiments were: (a) sequential applications of PRE and POST herbicides, and (b) POST herbicides applied as sequential or tank-mixed applications. Large crabgrass control was greater than 80% throughout the spring and summer when dithiopyr was applied PRE at 0.14 kg/ha late in February or when tank mixed at the same rate with sethoxydim at 0.11 kg/ha and applied POST in late May. Control was similar from a sequential program of dithiopyr applied PRE at 0.14 kg/ha in February and followed either by dithiopyr at 0.14 kg/ha or sethoxydim at 0.11 kg/ha as POST in early to mid-summer. Dithiopyr at 0.28 kg/ha as a POST application in late May did not control large crabgrass consistently. Control was > 80% for 6 to 8 wk when the POST dithiopyr treatment was repeated at the same rate 1 mo later. Sethoxydim applied POST controlled large crabgrass greater than 80% throughout the spring and summer when applied once at 0.22 kg/ha or twice at 0.11 kg/ha in each of two applications. Dithiopyr applied alone or with sethoxydim as sequential or tank-mixed treatments caused slight to moderate centipedegrass injury but was commercially acceptable (< 30%). However, injury from tank-mix herbicides was similar to either applied alone. Quinclorac severely injured (> 30%) centipedegrass, and 8 to 10 wk were required for recovery.
Effect of Rhizome Depth in Soil on Emergence and Growth of Field Mint (Mentha arvensis)
Authors: Ivany Jerry A.
Published: March 2018

Field mint is widespread on Prince Edward Island and has become a problem in the production of cereal grains, potatoes, and other crops. Studies were conducted to determine if deep burial of the rhizome could be used as a control method. Rhizome pieces measuring 2.5, 5.0, or 10.0 cm in length were hand-buried in soil at depths of 2.5, 5.0, 10.0, or 20.0 cm in the spring. As planting depth increased, shoot emergence was delayed and fewer shoots emerged throughout the season. The smallest rhizome of 2.5 cm produced the fewest shoots during the season, but larger rhizomes (5.0 or 10.0 cm long) produced greater amounts of shoot and rhizome dry weights than smaller rhizomes. Deep burial of field mint to 20.0 cm by inversion plowing could be used as a means of field mint control, especially in early planted competitive crops that close canopy quickly.
Weed Control in Low-Tannin Seedling Sericea Lespedeza (Lespedeza cuneata)
Authors: Wehtje Glenn , Walker Robert H. , Jones James D.
Published: March 2018

Field trials were conducted to evaluate weed control and crop safety with postemergence-applied herbicides in two cultivars of low-tannin seedling sericea lespedeza (Lespedeza cuneata). Two applications of either 2,4-D amine at 0.28 kg ae/ha or 2,4-DB amine at 0.56 kg ae/ha controlled sicklepod (Senna obtusifolia) ≥ 90%. Equivalent control of smallflower morningglory (Jacquemontia tamnifolia) required either two applications of 2,4-D or three of 2,4-DB. Three applications of either herbicide were required for comparable spotted spurge (Euphorbia maculata) control. Sericea lespedeza was not adversely affected when either herbicide was applied up to three times per season over two consecutive seasons. Tolerance to 2,4-D and 2,4-DB was equal between two sericea lespedeza cultivars. Absorption of foliar-applied14C-2,4-D was greater in sicklepod and smallflower morningglory than in sericea lespedeza. Translocation of absorbed14C-2,4-D was equivalent between sicklepod and sericea lespedeza but greater in smallflower morningglory than in sericea lespedeza. Absorption and translocation of foliar-applied14C-2,4-DB was equivalent between sicklepod and sericea lespedeza. Furthermore,14C-2,4-DB absorption was less in smallflower morningglory than in sericea lespedeza.
Effect of Flumetsulam Plus Clopyralid Soil Residues on Several Vegetable Crops and on Sweet Corn (Zea mays) Cultivars Grown in Rotation
Authors: O'Sullivan John , Thomas Robert J. , Bouw William J.
Published: March 2018

The effect of soil residues of flumetsulam plus clopyralid on several vegetable crops grown in rotation with field corn was investigated over 2 yr. The effect of soil residues of flumetsulam plus clopyralid on sweet corn cultivars of varying sensitivity to acetolactate synthase (ALS)-inhibiting herbicide was also investigated. Flumetsulam plus clopyralid was applied preemergence (PRE) to field corn at 0, 50 + 135, and 100 + 270 g ai/ha, respectively, in 1993 and 1994. Cucumber, tomato, cabbage, potato, pepper, pea, and sweet corn were planted each spring, both 1 and 2 yr following the herbicide application. Cabbage was very sensitive and showed visible injury symptoms and yield reductions both years following flumetsulam plus clopyralid application. Pepper showed a yield reduction only in 1995. All other crops showed no injury or yield reductions. Flumetsulam plus clopyralid was applied PRE and postemergence (POST) to six sweet corn cultivars in 1995. These six sweet corn cultivars were replanted into the same site 1 yr later. Flumetsulam plus clopyralid severely injured three of six sweet corn cultivars in 1995, the year of application. Soil residues 1 yr later, however, did not injure or reduce yield of any sweet corn cultivars, including cultivars sensitive to ALS-inhibiting herbicides.
Cost and Weed Management with Herbicide Programs in Glyphosate-Resistant Cotton (Gossypium hirsutum)
Authors: Askew Shawn D. , Wilcut John W.
Published: March 2018

Studies were conducted at Clayton, Goldsboro, and Rocky Mount, NC, to evaluate weed and cotton response to herbicide programs in glyphosate-resistant cotton. Just prior to cotton harvest, programs containing norflurazon, trifluralin, fluometuron, glyphosate, MSMA, cyanazine, and/or pyrithiobac in various combinations controlled common lambsquarters, common ragweed, goosegrass, ivyleaf morningglory, and smooth pigweed at least 94%. Glyphosate-resistant cotton injury was no more than 5%. Yields for glyphosate programs differed only at Clayton, where glyphosate programs containing residual herbicides yielded more than glyphosate alone. Depending on location, programs utilizing glyphosate as needed required a minimum of two and a maximum of four applications to prevent yield loss when minimal soil-applied herbicides were used. Other as-needed programs required one-three glyphosate applications, depending on location. For comparison based on application, herbicide, and adjuvant costs, the standard program of trifluralin preplant incorporated (PPI), pyrithiobac postemergence (POST), and fluometuron plus MSMA postemergence-directed (PD) was $119/ha compared with trifluralin PPI followed by (fb) two applications of glyphosate ($54/ha) or four applications of glyphosate ($94/ha).
Salt and Temperature Effects on Sethoxydim Spray Deposit and Efficacy
Authors: Matysiak Robert , Nalewaja John D.
Published: March 2018

Certain salts in the spray carrier can antagonize sethoxydim, while other salts overcome the antagonism or increase the herbicide's efficacy. Sethoxydim responses to salts have not been consistent, and the inconsistency is not completely understood. Experiments were conducted in the greenhouse to determine sethoxydim phytotoxicity to oat as influenced by salts in the spray carrier and by air temperature at and immediately after application as they alter the spray deposit characteristics. Thick amorphous spray deposits were related to ineffective sethoxydim-petroleum oil adjuvant treatments applied alone at 10 C or with bentazon at 10 or 25 C. Also, thin deposits with salt residues were related to ineffective sethoxydim treatments, as when sodium bicarbonate was present. Ammonium sulfate reduced or overcame antagonism of sethoxydim phytotoxicity caused by low temperature, bentazon, and sodium bicarbonate and gave thin deposits having close contact with the leaf epicuticular surface but without obvious salt deposits. UV light antagonism of sethoxydim phytotoxicity was different depending on temperature at and shortly after application and depending on salts in the spray mixture. The results indicate that salts in a bentazon spray carrier are in part antagonistic because of their effect on final spray deposit.