single application, and large areas would require overseeding ( Branham et al., 2005 ). In an unpublished Maryland study, however, four summer applications of the ester formulation of triclopyr applied at 1.12 kg·ha −1 a.i. were shown to safely control
of action similar to pyridine herbicides with efficacy for controlling annual and perennial broadleaf weeds ( Minogue et al., 2011 ; Strachman et al., 2010 ). Pyridine herbicides such as fluroxypyr and triclopyr are effective for postemergence
The tolerance of newly planted apple (Malus domestica Borkh.) and peach [Prunus persica (L.) Batsch] trees to the postemergence herbicide triclopyr was evaluated infield trials. Apple and peach trees were not injured by triclopyr applied at rates ranging from 0.28 to 1.12 kg acid equivalent (a.e.)/ha as a directed spray to soil. No injury was observed following direct application of 10 ml of a triclopyr solution at 2 g a.e./liter to the lower bark of either tree species. Applications of that solution to an individual branch injured or killed the treated apple or peach branch but did not affect the rest of the tree. No reduction in tree growth or injury was noted 1 year after triclopyr application. Applications of 10 ml of a glyphosate solution at 15 g a.i./liter to an apple branch caused severe injury and a growth reduction by 1 year after application, and killed all treated peach trees when applied to one branch. No triclopyr or 2,4-D treatment had affected apple or peach trunk diameter, number of branches, or tree size 1 year after application. Chemical names used: N-(phosphonomethyl)glycine (glyphosate); [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr); (2,4-dichlorophenoxy)acetic acid (2,4-D).
Corp.), and triclopyr (Garlon 3A, Dow AgroSciences) were used ( Table 1 ). Each herbicide was applied with the label recommended adjuvant ( Table 1 ). A nontreated control was also included ( Table 1 ). Because of the high efficacy of clopyralid and low
Triclopyr was applied once or twice in consecutive years to Virginia creeper [Parthenocissus quinquefolia (L.) Planch.] that was growing along the ground beneath the peach [Prunus persica (L.) Batsch.] tree canopy. All rate (0 to 1.1 kg·ha-1) and month combinations controlled Virginia creeper during the season of application. A single application of triclopyr at 1.1 kg·ha-1 was insufficient for control beyond 1 year. Satisfactory control of Virginia creeper was obtained with two applications of triclopyr at 1.1 kg·ha-1 made in either August or September. Chemical name used: [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr).
acid (i.e., triclopyr plus 2,4-D) applied at 3360 to 5040 g·ha −1 was required to provide 60% to 79% trumpetcreeper control ( Nice et al., 2006 ). Therefore, while older chemicals that mimic indole-3-acetic acid can suppress trumpetcreeper, it is
Several concentrations of mefluidide (Embark), a plant growth regulator; sethoxydim (Poast), a grass herbicide; and triclopyr (Rely) a nonselective herbicide, were evaluated to determine if italian ryegrass (Lolium multiflorum Lam.) growth could be suppressed. Ryegrass grows prolifically during the winter in states adjacent to the Gulf of Mexico and may serve as a living mulch for strawberry (Fragaria×ananassa Duch.) and other winter crops if its growth can be controlled. Different chemicals and concentrations were screened over 5 years for their efficacy to produce living mulch. Mefluidide produced good ryegrass control but was not evaluated after Study 1 because it is designed for industrial use and does not have an U.S. Environmental Protection Agency fruit crop label. Triclopyr, which has a label for several fruit crops, was studied only in the final year and it provided desired ryegrass control at the 0.016 and 0.030 mL·L-1 (parts per thousand) rate. Prime oil (paraffin base petroleum oil + polyol fatty acid esters) concentration affected results when sprayed with various sethoxydim rates. We concluded that 0.156 mL·L-1 sethoxydim plus 0.25 mL·L-1 prime oil will control ryegrass growth at the desired level (reduce growth by 40% to 50%) for living mulch. These rates are too low to cause much ryegrass browning. Chemical names used: N-[2,4dimethyl-5-[[(trifluoromethyl)-sulfony]amino]phenyl]acetamide, 2-[1-(ethoxylmino)buty1]-5-[2-(ethylthio)propy1]-3-hydroxy-2-cyclohexen-1-one), and ammonium-Dl-homoalanin-4-yl-(methyl) phosphinate.
With increasing pressure to reduce disposal of yard waste in landfills, many homeowners are seeking alternative methods for grass clipping disposal. When turf is treated with pesticides, the collected grass clippings become a potential source of injury to susceptible plants that come in contact with the clippings. In this study, grass clippings were collected at 2, 7, and 14 days after pesticide treatment from a turf treated with chlorpyrifos, clopyralid, 2,4-D, flurprimidol, isoxaben, or triclopyr. The clippings were used as a mulch around Lycopersicon esculentum Mill. (tomato), Phaseolus vulgaris L. (bush bean), Petunia ×hybrida Hort. Vilm.-Andr. (petunia), and Impatiens wallerana Hook. f. (impatiens). Beans were planted 4 weeks prior to mulching, whereas the other plants were grown in the greenhouse for 6 weeks and transplanted into the field 2 weeks prior to mulching. Clippings containing residues of clopyralid, 2,4-D, or triclopyr killed tomato, bean, and petunia plants when used 2 days after pesticide treatment (DAPT) and severely injured these same species when mulched 7 and 14 DAPT. Flurprimidol injured tomato, impatiens, and bean plants when present on mulch collected 2, 7, and 14 DAPT, but was not lethal. Flurprimidol slowed plant growth, caused darker green leaf color, and reduced flowering when mulched at 2 DAPT. Isoxaben injured tomato and bean plants when present on mulch used 2, 7, and 14 DAPT but was not lethal. Injury was not as severe in the second year of the study, indicating different environmental stresses and climatic conditions make predicting pesticide injury for all growing seasons difficult; however, grass clippings from a turf treated with herbicides or plant growth regulators should not be used for mulch around sensitive plants for at least 14 DAPT. Chemical names used: 0,0-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphorothioate (chlorpyrifos); 3,6-dichloro-2-pyridinecarboxylic acid, triethylamine salt (clopyralid); 2,4-dichlorophenoxyacetic acid, dimethylamine salt (2,4-D); α-(1-methylethyl)-α-[4-(trifluromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol); N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide and isomers (isoxaben); 3,5,6-trichloro-2-pyridinyloxy acetic acid, triethylamine salt (triclopyr).
Abstract
Herbicides were introduced into the vascular systems of 20-and 22-year-old Chinese elm (Ulmus parvifolia Jacq.), pin oak (Quercus palustris Muenchh.), and 20-year-old white ash (Fraxinus americana L.) with a syringe-type pressure injector. Concentrations of triclopyr [[(3,5,6,-trichloro-2-pyridinyl)oxy]acetic acid] triethylamine salt ranging from 90 to 360 g/liter were as effective on all species with 2 injection sites per tree as the combination of picloram (4-amino-3,5,6-trichloropicolinic acid) triisopropanolamine salt + 2,4-D [(2,4-dichlorophenoxy) acetic acid) triisopropanolamine salt at dosages ranging from 8 g/liter + 30 g/liter to 32 g/liter + 120 g/liter. Over 80% kill of Chinese elm tops occurred within 2 months after injection, whereas maximum kill of white ash and pin oak did not occur until the following growing season.
The synthetic auxins NAA and 3,5,6-TPA were investigated for reducing abscission of mature citrus fruit in California (CA). NAA was investigated on navel orange trees in San Joaquin Valley and southern CA locations. Of the seven NAA experiments presented, five had substantial fruit drop. In these five experiments, a treatment of NAA reduced drop by 31% to 88% compared to the untreated control. Although NAA treatments as low as 25 mg·L-1 (acid equivalent) reduced drop, the greatest reductions in drop were obtained by spray concentrations in the 100 to 400 mg·L-1 range. 3,5,6-TPA was investigated for fruit drop control properties on navel orange and grapefruit grown in various CA locations. The untreated control in seven of the ten 3,5,6-TPA experiments had substantial fruit drop. In each of these cases, a treatment of 10, 15 or 20 mg·L-1 (acid equivalent) of 3,5,6-TPA reduced drop 69% to 96% compared to the untreated control. A strong linear response from 3,5,6-TPA in these seven experiments indicates maximum fruit drop reduction from the highest rate investigated. On an acid equivalent basis 3,5,6-TPA seems to be comparable to 2,4-D. Both NAA and 3,5,6-TPA were effective in controlling preharvest fruit drop in citrus under CA conditions. Both materials provided fruit holding late into the harvest season. NAA, and in particular 3,5,6-TPA, offer the potential to provide a substitute for 2,4-D which is commonly used for controlling fruit drop in many countries. Chemical names used: naphthaleneacetic acid (NAA); 3,5,6-trichloro-2-pyridinyloxyacetic acid (3,5,6-TPA, triclopyr); 2,4-dichlorophenoxyacetic acid (2,4-D).