Biochemical Effects of Imazapic on Bermudagrass Growth Regulation, Broomsedge (Andropogon virginicus) Control, and MSMA Antagonism

Weed Science ◽  
2015 ◽  
Vol 63 (3) ◽  
pp. 596-603 ◽  
Author(s):  
Patrick E. McCullough ◽  
Jialin Yu ◽  
Donn G. Shilling ◽  
Mark A. Czarnota ◽  
Christopher R. Johnston
Keyword(s):  
Growth Inhibition ◽  
Laboratory Experiments ◽  
Growth Regulation ◽  
Field Experiments ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Shoot Biomass ◽  
Differential Growth ◽  
Greenhouse Experiments ◽  
Biochemical Effects

Broomsedge populations have increased substantially over the last decade on roadsides in Georgia. The invasiveness of this species might have resulted from imazapic use for bermudagrass growth regulation and the limited use of MSMA on roadsides. The objectives of this research were to evaluate (1) differential growth inhibition of bermudagrass and broomsedge to imazapic, (2) susceptibility of isolated acetolactate synthase (ALS) enzymes of bermudagrass and broomsedge to imazapic, (3) broomsedge control with tank mixtures of imazapic with MSMA, and (4) the influence of imazapic on absorption and translocation of14C-MSMA. In greenhouse experiments, imazapic reduced bermudagrass shoot biomass ~ 2 times more from the nontreated than broomsedge. Isolated ALS enzymes of bermudagrass were ~ 100 times more susceptible to inhibition by imazapic than broomsedge. In field experiments, imazapic provided no control of broomsedge, but MSMA alone controlled broomsedge 81% at 12 mo after initial treatments (MAIT). Broomsedge control was reduced to 45% when MSMA was tank mixed with imazapic at 12 MAIT. In laboratory experiments, imazapic tank mixtures did not reduce broomsedge absorption or translocation of14C-MSMA. Overall, bermudagrass is more susceptible to imazapic due to greater target-site inhibition than broomsedge. Results emphasize the importance of MSMA use for broomsedge control, but agronomists should avoid tank mixtures with imazapic to reduce potential antagonism.

Nicosulfuron Resistance and Metabolism in Terbufos- and Naphthalic Anhydride-Treated Corn

Weed Science ◽  
1995 ◽  
Vol 43 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Balazs Siminszky ◽  
Frederick T. Corbin ◽  
Yvonna Sheldon
Keyword(s):  
Laboratory Experiments ◽  
Acetolactate Synthase ◽  
Synergistic Interaction ◽  
Differential Sensitivity ◽  
Severe Injury ◽  
Seed Treatments ◽  
Naphthalic Anhydride ◽  
Corn Seed ◽  
Greenhouse Experiments ◽  
Target Enzyme

Synergistic interaction between the insecticide terbufos and the herbicide nicosulfuron may result in severe injury to corn. Greenhouse and laboratory experiments were conducted to determine if using the imidazolinone-resistant corn ‘Pioneer-3343 IR’ (P-3343 IR) or coating corn seeds with naphthalic anhydride (NA) would reduce herbicidal injury imposed by the nicosulfuron-terbufos interaction. Greenhouse experiments showed nicosulfuron-terbufos interactions resulting in herbicidal injury in both P-3343 IR and ‘DeKalb 689’ (D-689) corn varieties, but the D-689 was more sensitive than the P-3343 IR corn. The greenhouse experiments also demonstrated protection against the nicosulfuron-terbufos interaction by NA seed treatments. Studies with radiolabeled nicosulfuron showed that terbufos inhibited the metabolism of nicosulfuron, but pretreatment of D-689 and P-3343 IR corn seed with NA decreased the inhibition in excised corn leaves. The differences in sensitivity to nicosulfuron in the two corn varieties resulted in part from the differential metabolism and primarily from the differential sensitivity of the target enzyme, acetolactate synthase, to the herbicide.

Common Bermudagrass Seedhead Suppression and Growth Regulation with Fenoxaprop

2011 ◽  
Vol 25 (3) ◽  
pp. 404-410 ◽  
Author(s):  
J. T. Brosnan ◽  
G. K. Breeden ◽  
G. R. Armel ◽  
J. J. Vargas
Keyword(s):  
Aboveground Biomass ◽  
Growth Regulation ◽  
Field Experiments ◽  
Additional Research ◽  
Greenhouse Experiments ◽  
Common Bermudagrass ◽  
Significant Injury

Options for suppressing bermudagrass seedheads in managed turfgrass systems are limited. Experiments were conducted in 2009 and 2010 evaluating the use of fenoxaprop (25, 50, 75, and 100 g ha−1) for ‘Riviera’ bermudagrass seedhead suppression and growth regulation compared to imazapic (52 g ha−1), trinexapac-ethyl (91 g ha−1) and mefluidide (561 g ha−1). In field experiments, seedhead suppression ranged from 77 to 100% for fenoxaprop and imazapic at 35 d after treatment (DAT). Comparatively, seedhead suppression was < 25% for either trinexapac-ethyl or mefluidide at 35 DAT. Seedhead suppression was > 90% from 7 to 35 DAT for fenoxaprop applied at ≥ 50 g ha−1. Injury, determined visually, from fenoxaprop and imazapic in both the field and greenhouse measured < 25% on all rating dates, with no significant injury present after 21 DAT. In greenhouse experiments, fenoxaprop and trinexapac-ethyl showed similar reductions of bermudagrass growth; no differences in aboveground biomass were detected between these treatments at 42 DAT. Results of the current study illustrate that fenoxaprop and imazapic can be applied for bermudagrass seedhead suppression and growth regulation if moderate (< 25%) injury can be tolerated up to 21 DAT. Additional research is needed to evaluate the use of fenoxaprop and imazapic for seedhead suppression on other common and hybrid bermudagrasses.

Creeping Bentgrass (Agrostis stolonifera) Putting Green Tolerance to Bispyribac-Sodium

2009 ◽  
Vol 23 (3) ◽  
pp. 425-430 ◽  
Author(s):  
Patrick E. McCullough ◽  
Stephen E. Hart
Keyword(s):  
Growth Inhibition ◽  
Field Experiments ◽  
Creeping Bentgrass ◽  
Agrostis Stolonifera ◽  
Root Weight ◽  
Putting Greens ◽  
Annual Bluegrass ◽  
Greenhouse Experiments ◽  
Chelated Iron ◽  
Putting Green

Bispyribac-sodium is an efficacious herbicide for annual bluegrass control in creeping bentgrass fairways, but turf tolerance and growth inhibition may be exacerbated by low mowing heights on putting greens. We conducted field and greenhouse experiments to investigate creeping bentgrass putting green tolerance to bispyribac-sodium. In greenhouse experiments, creeping bentgrass discoloration from bispyribac-sodium was exacerbated by reductions in mowing height from 24 to 3 mm, but mowing height did not influence clipping yields or root weight. In field experiments, discoloration of creeping bentgrass putting greens was greatest from applications of 37 g/ha every 10 d, compared to 74, 111, or 222 g/ha applied less frequently. Chelated iron effectively reduced discoloration of creeping bentgrass putting greens from bispyribac-sodium while trinexapac-ethyl inconsistently reduced these effects. Overall, creeping bentgrass putting greens appear more sensitive to bispyribac-sodium than higher mowed turf, but chelated iron and trinexapac-ethyl could reduce discoloration.

scholarly journals ALS–Resistant Annual Sedge (Cyperus compressus) Confirmed in Turfgrass

Weed Science ◽  
2016 ◽  
Vol 64 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Patrick E. McCullough ◽  
Jialin Yu ◽  
J. Scott McElroy ◽  
S. Chen ◽  
H. Zhang ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Acetolactate Synthase ◽  
Shoot Biomass ◽  
Resistance Level ◽  
Physiological Basis ◽  
History Of ◽  
Leaf Tissues ◽  
Als Inhibitors ◽  
Inhibitor Resistance ◽  
Als Inhibitor

Acetolactate synthase (ALS) inhibitors are widely used for POST control of sedges in turfgrass. A suspected resistant (R) biotype of annual sedge was collected from a bermudagrass turf in Georgia with a history of exclusive use of halosulfuron. Research was conducted to evaluate the resistance level of this biotype to halosulfuron, efficacy of ALS-inhibiting herbicides and other mechanisms of action for control, and the molecular and physiological basis for resistance. In greenhouse experiments, the halosulfuron rate required to reduce shoot biomass 50% in comparison with the nontreated at 8 wk after treatment (WAT) were 8 and > 1,120 g ai ha−1for the S (susceptible) and R biotypes, respectively. Imazapic, sulfosulfuron, and trifloxysulfuron reduced biomass of the S biotype greater than 60% at 8 WAT, but biomass was reduced less than 20% for the R biotype. Glufosinate, glyphosate, MSMA, and sulfentrazone reduced shoot biomass of the R biotype by 93, 86, 97, and 45%, respectively. In laboratory experiments, the halosulfuron concentration required to inhibit ALS activity by 50% in excised leaf tissues was 5.8 and > 1,000 μM for the S and R biotypes, respectively. Gene sequencing of the R biotype revealed a Pro-197-Ser substitution that confers resistance to ALS inhibitors. This is the first report of ALS-inhibitor resistance in annual sedge and herbicide resistance in a sedge species from a turfgrass system.

Response of a Chlorsulfuron-Resistant Biotype ofKochia scopariato Sulfonylurea and Alternative Herbicides

Weed Science ◽  
1993 ◽  
Vol 41 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Lyle F. Friesen ◽  
Ian N. Morrison ◽  
Abdur Rashid ◽  
Malcolm D. Devine
Keyword(s):  
Field Experiments ◽  
Good Control ◽  
Acetolactate Synthase ◽  
In Vitro Assays ◽  
Shoot Biomass ◽  
Wheat Crop ◽  
Enzyme Assays ◽  
Dry Matter Accumulation ◽  
Severe Stunting

Kochia growing on an industrial site where chlorsulfuron was applied repeatedly over several seasons was confirmed to be resistant to chlorsulfuron and several other acetolactate synthase (ALS) -inhibiting herbicides. In growth room experiments, resistant (R) plants were 2 to >180 times more resistant to five sulfonylurea herbicides and one imidazolinone herbicide (imazethapyr) than susceptible (S) plants, as measured by the ratio of dosages required to inhibit shoot dry matter accumulation by 50% (GR50R/S). Similarly, in vitro assays of ALS activity indicated that from 3 to 30 times more herbicide was required to inhibit the enzyme from R plants than from S plants. Results of ALS enzyme assays indicated that R kochia was approximately equally resistant to metsulfuron, triasulfuron, and thifensulfuron, and 2.5 times more resistant to tribenuron than thifensulfuron. However, the response of R kochia growing in a spring wheat crop in the field was not consistent with results of the ALS enzyme assays. In field experiments, thifensulfuron at 32 g ai ha−1had little effect on R kochia. In contrast, metsulfuron, triasulfuron, and tribenuron at 8 g ha−1did not reduce R kochia seedling densities, but caused severe stunting such that 2 mo after treatment the shoot biomass of plants in untreated plots was four times greater than in sprayed plots. Herbicides with alternative modes of action including fluroxypyr, bromoxynil/MCPA ester, dichlorprop/2,4-D ester, and 2,4-D ester provided good control of R kochia in the field. Quinclorac did not reduce kochia densities, but surviving plants were stunted. To delay or avoid development of ALS inhibitor-resistant kochia populations, these alternative herbicides applied alone or in tank mixtures could be incorporated into a herbicide rotation.

Glyphosate and Multiple Herbicide Resistance in Common Waterhemp (Amaranthus rudis)Populations from Missouri

Weed Science ◽  
2008 ◽  
Vol 56 (4) ◽  
pp. 582-587 ◽  
Author(s):  
Travis R. Legleiter ◽  
Kevin W. Bradley
Keyword(s):  
Field Experiments ◽  
Acetolactate Synthase ◽  
The United States ◽  
Multiple Resistance ◽  
Complete Control ◽  
Individual Female ◽  
Common Waterhemp ◽  
Greenhouse Experiments ◽  
Treatment Tank ◽  
Amaranthus Rudis

Field and greenhouse experiments were conducted to determine the level of glyphosate resistance in common waterhemp populations from Platte County (MO1) and Holt County, Missouri (MO2), and to determine the level and distribution of resistance to glyphosate, acetolactate synthase (ALS)–inhibiting herbicides, and protoporophyrinogen oxidase (PPO)–inhibiting herbicides across the MO1 site. Results from greenhouse experiments revealed that the MO1 and MO2 waterhemp populations were 19 and 9 times more resistant to glyphosate, respectively, than a susceptible waterhemp population. In field experiments, greater than 54% of waterhemp at the MO1 site survived 1.7 kg glyphosate ae ha−1(twice the labeled rate) 6 wk after treatment. Tank-mix combinations of ALS- and PPO-inhibiting herbicides with glyphosate also failed to provide complete control of the waterhemp population at the MO1 site. Collection and screening of seed from individual female waterhemp accessions revealed multiple resistance to glyphosate, ALS-, and PPO-inhibiting herbicides across the MO1 site. All 14 waterhemp accessions collected across the MO1 site exhibited greater than 65% survival to 2× rates of glyphosate and thifensulfuron, and these accessions were spread across a 5-km2(503-ha) area. Four waterhemp accessions collected across a 0.9-km2(87-ha) area also exhibited 26 to 38% survival to 2× rates of lactofen. The results from these experiments provide evidence and confirmation of the first glyphosate-resistant waterhemp population in the United States and reveal that multiple resistance to glyphosate, ALS-, and PPO-inhibiting herbicides can occur in waterhemp.

Herbicide-Resistant Sunflower (Helianthus annuus) Response to Soil Residues of ALS-Inhibiting Herbicides

2006 ◽  
Vol 20 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Kirk A. Howatt ◽  
Gregory J. Endres
Keyword(s):  
Helianthus Annuus ◽  
Seed Yield ◽  
Field Experiments ◽  
Biomass Accumulation ◽  
Acetolactate Synthase ◽  
Treated Soil ◽  
Herbicide Resistant ◽  
Greenhouse Experiments ◽  
Significant Injury

Sunflower lines developed to resist some acetolactate synthase (ALS)-inhibiting herbicides are susceptible to foliar applications of other ALS-inhibiting herbicides. Research was conducted to determine whether imidazolinone (IMI)- or sulfonylurea (SU)-resistant sunflower was affected by soil residues of imazethapyr, metsulfuron, or flucarbazone. In greenhouse experiments, IMI-sunflower displayed 60 and 66% injury 4 wk after emergence with incorporated soil residues of metsulfuron at 4.2 g ai/ha and flucarbazone at 30 g ai/ha, respectively, but response to imazethapyr at 35 g ai/ ha was not different from that of nontreated plants. Metsulfuron at 4.2 g/ha and flucarbazone at 30 g/ha resulted in 56 and 72% less biomass accumulation, respectively, of IMI-sunflower compared with that of nontreated plants. Incorporated soil residues of imazethapyr, metsulfuron, or flucarbazone did not cause significant injury or result in shorter plants or less biomass accumulation of SU-sunflower than nontreated sunflower in greenhouse experiments. In field experiments, nonincorporated residues of imazethapyr, metsulfuron, or flucarbazone did not induce visible chlorosis or significant stunting of IMI- or SU-sunflower compared with nontreated sunflower. Herbicide-resistant sunflower growing in soil with nonincorporated residues of imazethapyr, metsulfuron, or flucarbazone produced seed yield similar to sunflower growing in sulfentrazone-treated soil or nontreated soil.

scholarly journals Efficacy and Fate of Atrazine and Simazine in Doveweed (Murdannia nudiflora)

Weed Science ◽  
2016 ◽  
Vol 64 (3) ◽  
pp. 379-388 ◽  
Author(s):  
Jialin Yu ◽  
Patrick E. McCullough
Keyword(s):  
Photosystem Ii ◽  
Dose Response ◽  
Laboratory Experiments ◽  
Shoot Biomass ◽  
Greenhouse Experiments ◽  
Root Absorption ◽  
Application Placement ◽  
Time Required ◽  
Murdannia Nudiflora ◽  
Uptake And Metabolism

Doveweed is a summer annual that is difficult to control in turfgrass. Photosystem II inhibitors have the potential to control doveweed, but research is limited on the efficacy of these herbicides. The objectives of this research were to evaluate (1) the differential tolerance levels of doveweed to atrazine and simazine, (2) the influence of application placement and rate on herbicide efficacy, and (3) uptake and metabolism of these herbicides in doveweed. In greenhouse experiments, the time required to injure doveweed 50% was three to five times faster for atrazine than simazine. Simazine soil or foliar + soil application reduced doveweed biomass 77% from the nontreated, but foliar-only treatments reduced biomass 51%. Application placements for atrazine equally reduced shoot biomass 96% from the nontreated. In a dose–response experiment, atrazine and simazine required ≤ 1.8 kg ha−1and ≥ 5.1 kg ha−1to injure doveweed 50% from 8 to 16 d after treatment (DAT), respectively. Doveweed required 79% less atrazine to reduce biomass 50% from the nontreated compared with simazine. In laboratory experiments, doveweed had similar root absorption levels of14C-atrazine and14C-simazine. Metabolism of both herbicides linearly increased from 1 to 7 DAT, but parent herbicide levels averaged 39 and 25% of the extracted radioactivity from14C-atrazine and14C-simazine, respectively. Doveweed metabolized14C-simazine to three major metabolites, including hydroxysimazine, that each ranged from 24 to 29% of the extracted radioactivity. Hydroxyatrazine was the only major metabolite (> 10% of total14C extracted) of14C-atrazine. Overall, doveweed has slower metabolism of atrazine compared with simazine and is the basis for differential tolerance levels to these herbicides.

Concentration of Impurities during Melting of Snow Made from Secondary Sewage Effluent

1986 ◽  
Vol 18 (2) ◽  
pp. 151-156 ◽  
Author(s):  
R. Zapf-Gilje ◽  
S. O. Russell ◽  
D. S. Mavinic
Keyword(s):  
Potassium Chloride ◽  
Chloride Solution ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Low Cost ◽  
Sewage Effluent ◽  
Potassium Chloride Solution ◽  
Laboratory Results ◽  
Solution Field ◽  
Concentration Of Impurities

When snow is made from sewage effluent, the impurities become concentrated in the early melt leaving the later runoff relatively pure. This could provide a low cost method of separating nutrients from secondary sewage effluent. Laboratory experiments showed that the degree of concentration was largely independent of the number of melt freeze cycles or initial concentration of impurity in the snow. The first 20% of melt removed with it 65% of the phosphorus and 90% of the nitrogen from snow made from sewage effluent; and over 90% of potassium chloride from snow made from potassium chloride solution. Field experiments with a salt solution confirmed the laboratory results.

EFFECTS OF SOIL ACIDITY ON RHIZOBIA NUMBERS, NODULATION AND NITROGEN FIXATION BY ALFALFA AND RED CLOVER

1977 ◽  
Vol 57 (2) ◽  
pp. 197-203 ◽  
Author(s):  
W. A. RICE ◽  
D. C. PENNEY ◽  
M. NYBORG
Keyword(s):  
Nitrogen Fixation ◽  
Soil Ph ◽  
Soil Acidity ◽  
Field Experiments ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Red Clover ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Greenhouse Experiments

The effects of soil acidity on nitrogen fixation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were investigated in field experiments at 28 locations, and in greenhouse experiments using soils from these locations. The pH of the soils (limed and unlimed) varied from 4.5 to 7.2. Rhizobia populations in the soil, nodulation, and relative forage yields (yield without N/yield with N) were measured in both the field and greenhouse experiments. Rhizobium meliloti numbers, nodulation scores, and relative yields of alfalfa decreased sharply as the pH of the soils decreased below 6.0. For soils with pH 6.0 or greater, there was very little effect of pH on any of the above factors for alfalfa. Soil pH in the range studied had no effect on nodulation scores and relative yields of red clover. However, R. trifolii numbers were reduced when the pH of the soil was less than 4.9. These results demonstrate that hydrogen ion concentration is an important factor limiting alfalfa growth on acid soils of Alberta and northeastern British Columbia, but it is less important for red clover. This supports the continued use of measurements of soil pH, as well as plant-available Al and Mn for predicting crop response to lime.

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