Oryzalin, simazine, and metolachlor alone and in combination were evaluated for weed control in field-grown Korean boxwood (Buxus microphylla Siebold & Zucc. ‘Koreana’) and Photinia (Photinia × fraseri) at Belle Mina, Ala., over a 3-year production period. Treatments were applied twice during each growing season. Greatest control of the annual grass and broadleaf weed species was with oryzalin tank-mixed simazine at rates of either 2.2 + 0.8 or 3.4 + 1.1 kg a.i. per ha−1, respectively. These treatments were not injurious to either species and consistently resulted in the highest growth indices. No injury was detected when additional liners of boxwood were planted in the treated plots at the termination of the experiment. Chemical names used: 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin); 6-chloro-N,N’-diethyl-1,3,5-triazine-2,4-diamine (simazine); and 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor).
Methazole [2-(3,4-dichlorophenyl)-4-methy1-1,2,4-oxadiazolidine-3,5-dione] napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], oryzalin [3,5-dinitro-N4 ,N4 -dipropyl-sulfanilamide], oxadiazon [2-tert-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-∆2-l,3,4-oxadiazolin-5-one], and simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] each at 4.5 kg/ha were applied preemergence on June 17, 1976 in a nursery of 6-month-old seedlings of peach [Prunus persica (l.) Batsch cv. Nemaguard]. Though simazine and oryzalin provided better weed control, oxadiazon increased seedling height and trunk diameter from 25 to 89 days after application. All treatments impeded bark adhesion (slippage) 25 days after application but not after either 56 or 89 days. No phytotoxicity was observed from any treatment.
Herbicides were applied to container-grown herbaceous perennials and evaluated on the basis of weed control, phytotoxicity, and effect on plant growth. During the 1995 season six preemergent herbicides [(in kg·ha–1) Napropamide (Devrinol 10G), 4.5 and 9.1; Isoxaben (Gallery 75DF), 1.1 and 2.3; Oxadiazon (Ronstar 2G), 4.5 and 9.1; Oxyfluorfen + Oryzalin (Rout 3G), 3.4 and 13.6; Oryzalin (Surflan AS), 2.8 and 4.5; and Trifluralin (Treflan 5G) 4.5 and 9.1, were tested on Callirhoe involucrata, Delosperma nubigenum, Dendranthemum ×morifolium `Jennifer', Festuca cinerea `Sea Urchin', and Gypsophila paniculata `Fairy's Pink'. Isoxaben (both rates) resulted in visual phytotoxicity symptoms and sometimes death to Dendranthemum. Oxadiazon (9.1 kg·ha–1) and Oxyfluorfen + Oryzalin (both rates) resulted in plant chlorosis and necrosis to Delosperma soon after herbicide application, but plants outgrew herbicide damage. Napropamide (both rates), applied to Delosperma, resulted in less dry weight when compared to some of the other herbicide treatments. Oryzalin (4.5 kg·ha–1) resulted in visual phytotoxicity and less plant dry weight to Festuca. Data analysis revealed no significant differences in Callirhoe and Gypsophila. In general, most herbicides controlled weeds effectively.
Field studies were conducted to determine the efficiency and crop safety of trifluralin [2,6-dinitro-N, N-dipropyl-4(trifluoromethyl) benzenamine] in coriander (Coriandrum sativum L.), dill (Anethum graveolens L.), and dandelion greens (Taraxacum officinale Weber) when applied preplant-incorporated at 0.56 and 0.84 kg a.i./ha. Visual injury evaluations, crop fresh and dry weight at maturity, and leaf area were used to determine adverse effects of trifluralin on each crop when compared to an untreated control. Dandelion greens had a 47% and 49% reduction in leaf area when treated with trifluralin at 0.56 and 0.84 kg a.i./ha when compared to the untreated weed-free dandelion treatment. Coriander and dill showed no visual crop phytotoxicity and no adverse effects on crop growth, fresh and dry weight yield, or leaf area when treated with trifluralin. Trifluralin, when used in combination with early season mechanical cultivation, can provide selective weed control of many of the most common winter annual weeds in south Texas while exhibiting a high level of crop tolerance for coriander and dill.
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).
Sequential applications of granular oxyfluorfen (2 G) at 3.3 kg a.i.·ha−1, oxadiazon (2 G) at 3.3 kg a.i.·ha−1, napropamide (10 G) at 4.5 kg a.i.·ha−1, and chlorpropham (20 G) at 1.1 kg a.i.·ha−1 were evaluated for weed control in newly planted Rhododendron obtusum (Lindl.) Planch cv. Hinocrimson azaleas in the field. Granular oxyfluorfen, oxadiazon, or napropamide applied twice per season controlled 99%, 77%, or 73% of the weeds, respectively, for 2 years. A combination of napropamide, oxyfluorfen, and oxadiazon applied twice per season controlled >99% of the weeds at the season's end. Single seasonal applications of oxyfluorfen or oxadiazon controlled 63% and 77% of the weeds, respectively. Phytotoxicity to azaleas was not observed with any treatment. Chemical names used: 2-chloro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyel)benzene (oxyfluorfen); 3-[2,4-dichloro-5-(l-methylethoxy)phenyl]-5-(l,l-dimethylethyl)-l,3,4-oxadiazol-2(3 H)-one (oxadiazon); 2-(α-napththoxy)-N,N-diethylpropionamide (napropamide); and 1-methylethyl 3-chlorophenyl carbamate (chlorpropham).
Midsummer grapehoeing following spring application of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] or simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] plus paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) adequately controlled weeds growing in grapes (Vitis labrusca L.). When grapehoeing was used to control grape root borer [(Vitacea polistiformis Harris) lower initial rates of preemergence herbicide could be used. An additional half-rate of herbicide was required after grapehoeing to maintain weed control through the fall. Plots not grapehoed were almost completely weed free following a glyphosate [N-(phosphonomethyl)glycine] treatment. Injury to grapes the following spring was associated with fall glyphosate applications where low hanging foliage, that had not been removed, intercepted the spray. Glyphosate was most effective and paraquat more effective than dinoseb (2-sec-buty1-4,6-dinitrophenol) plus diesel fuel for postemergence control of weeds in grapes. Preemergence herbicides, napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone], oxadiazon [2-tert-buty1-4-(2,4-dichloro-5-isopropoxyphenyl)-∆2-l,3,4-oxadiazolin-5-one], oryzalin (3,5-dinitro-N 4,N 4-dipropylsulfanilamide), and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene], were effective as residual type treatments.
several weed species and an increase in numbers of weeds that are naturally tolerant of these herbicides ( Gower et al., 2004 ; Peachey et al., 2011 ; Richardson and Zandstra, 2006 ). Regardless of resistance problems, chemical weed control is essential
Yields and economic returns above treatment variable costs were determined for young `Desirable' pecan [Carya illinoinensis (Wangenh.) C. Koch] trees grown for nine seasons under ten combinations of orchard floor management practice and irrigation. Orchard floor management practices were 1) no weed control, 2) mowed, 3) total weed control with herbicides, 4) grass control only with herbicides, or 5) disking, and trees were either irrigated or nonirrigated. Total weed control with herbicides increased cumulative yield through the ninth growing season by 358% compared to no weed control. In the humid environment where this experiment was conducted, irrigation did not increase crop value obtained from the young trees, except for 1 year. At the end of the ninth season, total weed control with herbicides was the only treatment to have a positive net present value. These data indicate that establishment costs for young `Desirable' pecan trees can be recovered as early as the eighth growing season if competition from weeds is totally eliminated.
Combinations of seeding rate, spacing, and weed control treatments were evaluated for their effect on the performance of the Virginia Tech transplanted meadow technique. The treatments consisted of seeding at 112 or 56 g·90 m−2; within-row transplant spacing of 30, 45, or 60 cm; and mulching, oryzalin application, or no weed control measures. Plant competition alone was insufficient, whereas oryzalin was the most effective for weed control but also reduced the plant stand and floral display. Mulch provided effective weed control with maximum floral display. Close transplant spacing within rows resulted in quick site coverage initially, but this advantage disappeared after 8 weeks compared to wider spacing. Seeding rate did not affect site coverage until the meadow reached maturity at 12 weeks. The lower seed rate allowed more lodging, resulting in a more open appearance and greater canopy light transmission. Chemical name used: 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin).