cultivation at 15% canopy development ( Tables 2 and 3 ). Weed control was consistently 85% or greater in ‘Russet Burbank’ and ‘Bannock Russet’ with s-metolachlor and metribuzin PRE in-row banded with cultivation at 15% canopy development. Table 2. Between
Renata L. Solan, Jed B. Colquhoun, Richard A. Rittmeyer, and Daniel J. Heider
Qingren Wang, Waldemar Klassen, Edward A. Evans, Yungcong Li, and Merlyn Codallo
plastic mulch; 3) herbicides/OM: compost applied as an organic mulch, and the herbicides S-metolachlor (Dual Magnum®; Syngenta Crop Protection, Wilmington, DE) and napropamide (Devrinol®; Syngenta Crop Protection) applied in a tank mix to the organic mulch
S. Alan Walters and Bryan G. Young
several PRE herbicides including clomazone + ethalfluralin, halosulfuron-methyl, and s-metolachlor will provide better weed control in NT compared with many older cucurbit herbicides, the use of effective postemergence herbicides for control of both grass
Lambert B. McCarty, D. Wayne Porter, Daniel L. Colvin, Donn G. Shilling, and David W. Hall
Greenhouse studies were conducted at the Univ. of Florida to evaluate the effects of preemergence herbicides on St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] rooting. Metolachlor, atrazine, metolachlor + atrazine, isoxahen, pendimethalin, dithiopyr, and oxadiazon were applied to soil columns followed by placement of St. Augustinegrass sod on the treated soil. Root elongation and biomass were measured following application. Plants treated with dithiopyr and pendimethalin had no measurable root elongation and root biomass was severely (>70%) reduced at the study's conclusion (33 days). Root biomass was unaffected following isoxaben and oxadiazon treatments, but oxadiazon applied at 3.4 kg·ha-1 reduced root length by 50%. Atrazine at 2.2 kg·ha-1 and metolachlor + atrazine at 2.2 + 2.2 kg·ha-1, did not reduce root length in one study, while the remaining atrazine and metolachlor + atrazine treatments reduced cumulative root length and total root biomass 20% to 60%. Metolachlor at 2.2 kg·ha-1 reduced St. Augustinegrass root biomass by >70% in one of two studies. St. Augustinegrass root elongation rate was linear or quadratic in response to all treatments. However, the rate of root elongation was similar to the untreated control for plants treated with isoxaben or oxadiazon. Chemical names used: 6-chloro-N-ethyl-N'-(l-methylethyl)-1,3,5-triazine-2,4-diamine(atrazine);S,S-dimethyl2-(difluoromethyl)-4-(2-methylpropyl)-6-(t∼fluoromethyl)-3,5-pyridinecarbothioate (dithiopyr); N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide (isoxaben); 2-chloro-N-(2-ethyl- 6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).
Joseph C. Neal and Andrew F. Senesac
Preemergent herbicide phytotoxicity was evaluated for six species of container-grown ornamental grasses: beach grass (Ammophila breviligulata Fern.), pampas grass [Cortaderia selloana (Schult. & Schult. f.) Asch. & Graebn.], tufted hair grass [Deschampsia caespitosa (L.) Beauvois.], blue fescue [Festuca ovina cv. glauca (Lam.) W.D.J. Koch], fountain grass [Pennisetum setaceum (Forssk.) Chiov.], and ribbon grass (Phalaris arundinacea cv. picta L.). Herbicides included isoxaben, metolachlor, MON 15151, napropamide, oryzalin, oxadiazon, pendimethalin, prodiamine, and trifluralin; the granular combination products of benefin plus trifluralin; and oxyfluorfen plus pendimethalin. Metolachlor, granular or spray, and oryzalin severely injured all species tested, except beachgrass, which was not injured by metolachlor granule. Napropamide injured pampas grass, fountain, grass, blue fescue, and tufted hair grass, but was safe on ribbon grass and beach grass. Pendimethalin, prodiamine, trifluralin; MON 15151, isoxaben, oxyfluorfen plus pendimethalin, and benefin plus trifluralin were safe on all six species. Chemical names used: N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine(benefin);N-[3-(1-ethyl-1-methylpropyl)5-isoxazolyl]-2,6-dimethoxybenzamide(isoxaben);2-chloro-N-(2-ethyl-6-methylphenyll-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); S,S-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate(MON 15151);N,N-diethyl-2-(l-naphthalenyloxy)propanamide (napropamide); 4-(dipropylamino)-3,5-dinitro-benzenesulfonamide (oryzalin); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene (oxyfluorfen); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); N3,N3-di-n-propyl-2,4-dinitro-6-(trifluoromethyl)-m-phenylenediamine (prodiamine); 2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine (trifluralin).
Kassim Al-Khatib, Carl Libbey, and Sorkel Kadir
Broadleaf weed control with trifluralin, oxyfluorfen, pendimethalin, clopyralid, pyridate, and metolachlor in cabbage (Brassica oleracea L.) grown for seed was evaluated. No single herbicide controlled broadleaf weeds adequately, with the exception of pendimethalin at 1.92 and 3.84 kg a.i./ha. However, combinations of trifluralin + oxyfluorfen, pendimethalin + clopyralid, and oxyfluorfen + pyridate effectively controlled weeds and did not reduce seed yields. Herbicides caused slight to moderate injury symptoms to cabbage plants, with the greatest injury caused by pendimethalin and the least by trifluralin and metolachlor. However, plants recovered from these symptoms and appeared normal at the bud stage. None of the herbicides applied alone or in combinations adversely affected cabbage population, height, or flowering date. Chemical names used: 3,6-dichloro-2-pyridinecarboxylic acid (clopyralid); 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene (oxyfluorfen); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); O-(6-chloro-3-phenyl-4-pyridazin-yl)S-octylcarbonothioate (pyridate); 2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine (trifluralin).
Jeffrey F. Derr
This material is based on work supported by the Cooperative State Research Service, U.S. Dept. of Agriculture, under Project 6129900. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal
Peter A. Dotray and Cynthia B. McKenney
Experiments were conducted to evaluate established and seeded buffalograss [Buchloe dactyloides (Nutt.) Engelm.] tolerance to herbicides applied preemergence at labeled use rates. Established buffalograss tolerated benefin, benefin plus oryzalin, benefin plus trifluralin, DCPA, dithiopyr, isoxaben, oryzalin, pendimethalin, and prodiamine. For established buffalograss treated with atrazine, diuron, or metolachlor, the injury rating was 27% to 71% at 6 weeks after treatment (WAT) and 22% to 84% at 15 WAT. Buffalograss tolerated cyanazine, metsulfuron, propazine, and pyrithiobac applied in the seedbed. Seeded buffalograss stands were reduced by alachlor, atrazine, dicamba, linuron, metolachlor, metribuzin, oryzalin, pendimethalin, and quinclorac. Stand reductions by dicamba (a preplant and postemergence herbicide), up to 100% at 4 WAT and up to 85% at 16 WAT, were those most severe. Seeded and established buffalograss showed excellent tolerance to a few preemergence herbicides that could be used effectively and safely to control weeds during establishment and maintenance of buffalograss. Chemical names used: 2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide (alachlor); 6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine (atrazine); N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine (benefin); 2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methylpropanenitrile (cyanazine); dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate (DCPA); 3,6-dichloro-2-methoxybenzoic acid (dicamba); S,S-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate (dithiopyr); N′-(3,4-dichlorophenyl)-N,N-dimethylurea (diuron); N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide (isoxaben); N′-(3,4-dichlorophenyl)-N-methoxy-N-methylurea (linuron); 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one (metribuzin); 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]benzoic acid (metsulfuron); 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); N 3,N 3-di-n-propyl-2,4-dinitro-6-(trifluoromethyl)-m-phenylenediamine (prodiamine); 6-chloro-N,N′-bis(1-methylethyl)-1,3,5-triazine-2,4-diamine (propazine); 2-chloro-6-[(4,6-dimethoxy-2-pyrimidinyl) thio]benzoic acid (pyrithiobac); 3,7-dichloro-8-quinolinecarboxylic acid (quinclorac); Team™ [premix of 1.33% benefin and 0.67% 2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine] (trifluralin).
C.C. Shock, E.B.G. Feibert, L.D. Saunders, and S.R. James
`Umatilla Russet' and `Russet Legend', two newly released potato (Solanum tuberosum L.) cultivars were compared with four established cultivars (`Russet Burbank', `Shepody', `Frontier Russet', and `Ranger Russet'). Potatoes were grown under four, season-long, sprinkler irrigation treatments in three successive years (1992-94) on silt loam soil in eastern Oregon. At each irrigation, the full irrigation treatment received up to the accumulated evapotranspiration (ETc) since the last irrigation. Three deficit irrigation treatments had progressively less water. The new cultivars `Umatilla Russet' and `Russet Legend' performed as well as or better than the other cultivars in the full irrigation treatment, with `Umatilla Russet' showing a higher yield potential at the higher water application rates than `Russet Legend'. All cultivars produced more U.S. No. 1 tubers than `Russet Burbank', except in 1993, an unusually cool and wet year. `Russet Legend' was the only cultivar showing a tolerance to deficit irrigation. In two out of the three years, `Russet Legend' was as productive of U.S. No. 1 yield over most of the range of applied water as `Shepody', `Frontier Russet', and `Ranger Russet' were at the higher end of the applied water range. Chemical names used: 0,0-diethyl S-[(ethylthio) methyl] phosphorodithioate (phorate); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); and 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1methyl-ethyl) acetamide (metolachlor).
David Staats, James Klett, Teri Howlett, and Matt Rogoyski
During the 2005 season, three preemergence herbicides were applied to four container-grown herbaceous perennials and evaluated for weed control, phytotoxicity, and effect on plant growth. The herbicides and application rates were: 1) Pendimethalin (Pendulum 2G) 2.24, 4.48, and 8.96 kg/ha; 2) Trifluralin and Isoxaben (Snapshot 2.5 TG) 2.8, 5.6, and 11.2 kg/ha; and 3) S-metolachlor (Pennant Magnum 7.6 EC) 2.8, 5.6, and 11.2 kg/ha. Herbicides were applied to Coral Bells (Heuchera sanguinea), Hopflower Oregano (Origanum libanoticum), CORONADO™ Hyssop (Agastache aurantiaca), and SPANISH PEAKS™ Foxglove (Digitalis thapsi). Treatments were applied twice with 30 days between applications. Plants were evaluated for phytotoxicity after 1, 2, and 4 weeks after applying herbicide treatments. No phytotoxicity symptoms were apparent on any of the plants treated with Pendulum, and plant size (dry mass) was not affected. Snapshot resulted in visual phytotoxicity with Digitalis and Heuchera at the higher rates and also resulted in smaller plants. Pennant Magnum caused phytotoxicity at all rates in all plants and resulted in significantly smaller plants than the control. Weed control was very good with all herbicides, but did not control every weed.