Three commonly used nursery media were packed into 10×40 cm long PVC plastic columns. Two treatments of aqueous applied napropamide [2-(αnapthoxy)-N,N diethyl propionamide] were used including: 1) 13.44 kg/ha, 2) 20.16 kg/ha. Two water treatments were applied to the columns: 1) 2.54 cm/.405 ha, 2) 5.08 cm/.405 ha. Leachate from the columns was collected every three days for a period of two weeks. Quantitative bioassay testing using a napropamide sensitive plant species Hordeum vulgare L. (barley) have indicated a downward linear trend in the growth of roots and shoots when exposed to increasing concentrations of napropamide in controlled petri dish experiments. Preliminary leachate studies indicate that napropamide concentrations in the leachate collected are below levels detectable by the barley bioassay (< .25 ppm) at the label recommended rate of 6.72 kg/ha. Gas chromatography studies will be conducted to confirm napropamide concentrations in the collected leachate.
Scott G. Reeves and James E. Klett
James P. Gilreath, Timothy N. Motis, Bielinski M. Santos, Joseph W. Noling, Salvadore J. Locascio and Daniel O. Chellemi
Field studies were conducted during four consecutive tomato (Lycopersicon esculentum) -cucumber (Cucumis sativus) rotations to examine the longterm residual effects of tomato methyl bromide (MBr) alternatives on soilborne pests in double-cropped cucumber. Four treatments were established in tomato fields: a) nontreated control; b) MBr + chloropicrin (Pic) (67:33 by weight) at a rate of 350 lb/acre; c) tank-mixed pebulate + napropamide at 4 and 2 lb/acre, respectively, followed by 1,3-dichloropropene (1,3-D) + Pic (83:17 by volume) at 40 gal/acre; and d) napropamide at 2 lb/acre followed by soil solarization for 7 to 8 weeks. Each of the following seasons, cucumber was planted in the same tomato plots without removing mulch films. For nutsedge [purple nutsedge (Cyperus rotundus) and yellow nutsedge (C. esculentus)] densities, napropamide followed by solarization plots had equal control (≤15 plants/m2) as MBr + Pic during all four cropping seasons. However, nematode control with solarization was inconsistent. Marketable yield data proved that fumigation in tomato fields with either MBr + Pic or pebulate + napropamide followed by 1,3-D + Pic had a long-term effect on double-cropped cucumber.
Joseph C. Neal, Marvin P. Pritts and Andrew F. Senesac
Five greenhouse and two Geld experiments were conducted to evaluate tissue culture-propagated (TC) raspberry (Rubus idaeus cv. Heritage) sensitivity to preemergent herbicides. Plant performance was measured by plant vigor, above-ground fresh weight, root development, and primocane number. Simazine and oryzalin caused significant injury to newly planted TC raspberry plants in greenhouse and field experiments. The severity of injury was generally linear with respect to herbicide rate, but no appreciable differences in injury were observed between the granular and spray applications. Napropamide wettable powder caused some foliar injury, but plants recovered within one growing season and growth was equal or superior to the hand-weeded controls. The granular formulation of napropamide produced similar results, but did not cause the initial foliar burn. Pre-plant dipping of roots into a slurry of activated carbon did not prevent simazine or oryzalin injury, but injury was reduced when herbicide applications were delayed. Simazine applied 4 weeks after planting was not Injurious, and oqzalin applied 2 or 4 weeks after planting caused some foliar injury, hut no reduction in plant fresh weight. Delayed treatments of napropamide increased foliar injury. Herbicide tolerance of tissue-cultured plantlets appeared to be less than that of conventionally propagated plants. Chemical names used: N,N-diethyl-2-(1-napthalenyloxy)propanamide (napropamide), 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin), 6-chloro-N,N'diethyl-1,3,5-triazine-2,4-diamine (simazine).
Cosme A. Argerich, Kent J. Bradford and Floyd M. Ashton
The interactions of seed vigor with herbicides were studied with respect to seedling emergence, growth, and fruit yield of processing tomatoes (Lycopersicon esculentum Mill. cv. UC204C). Seed vigor (speed of germination) was enhanced by priming in an aerated solution of 0.12 m K2HP O4 plus 0.15 m KN O3 at 20C for 5 days followed by drying in forced air at 30C. The vigor of a second subsample of the same seed lot was reduced by controlled deterioration at 13% water content (dry-weight basis) for 6 days at 50C (aged seeds). Primed, aged, and untreated seeds were tested for their sensitivity to napropamide and metribuzin herbicides in greenhouse and field studies. A seed vigor × herbicide interaction was detected only under greenhouse conditions, where aged seeds were more sensitive than primed or untreated seeds to metribuzin. In April and May field plantings, seed vigor influenced the rate and percentage of final emergence and the earliness of fruit maturity, but had no effect on relative growth rate or total vegetative or reproductive yield. Napropamide at 4.5 and 9 kg·ha-1 and metribuzin at 0.4 and 0.8 kg·ha-1 had no effect on the rate or percentage of seedling emergence, relative growth rate, or total fruit yield. Metribuzin increased the mortality of seedlings at either application rate, and at 0.8 kg·ha-1 delayed early growth and fruit maturity in the April planting. Napropamide treatments did not differ from the water control for all characteristics and environments studied. Chemical names used: 4-amino-6-tert-butyl-3(methylthio)-1,2,4-triazin-5(4H)-one (metribuzin); 2-(α-napthoxy)-N,N-diethyl propionamide (napropamide).
David Staats, David Hillock and James E. Klett
Five preemergence herbicides were applied to seven herbaceous perennials to evaluate weed control efficacy and phytotoxicity. Different species were used each year. The species used during 1992 were coneflower (Rudbeckia fulgida Ait. `Goldstrum'), common foxglove (Digitalis purpurea L. `Excelsior'), Shasta daisy (Leucanthemum ×superbum Bergmans `Alaska'), Stokes's aster (Stokesia laevis Greene `Blue Danube'), and avens (Geum Quellyon Sweet `Mrs. Bradshaw'). The species used in 1993 were woolly yarrow (Achillea tomentosa L.) and woolly thyme (Thymus pseudolanuginosus Ronn.). The herbicides and rates were napropamide (Devrinol 10G) at 4 and 8 lb a.i./acre; metolachlor (Pennant 5G) at 4 and 8 lb a.i./acre; oxyfluorfen+oryzalin (Rout 3G) at 3 and 12 lb a.i./acre; trifluralin (Treflan 5G) at 4 and 8 lb a.i./acre; and oxadiazon (Ronstar 2G) at 4 and 8 lb a.i./acre. Plants were grown in no. 1 containers and weed seeds were sown onto the substrate surface. Two control treatments, no herbicides but with weeds (weedy control), and no weeds or herbicides (weed-free control) also were evaluated. Weed control was effective and similar for all herbicides tested. Napropamide at 8 lb a.i./acre caused stunting in foxglove (20% to 45% less growth compared to weed-free control). Oxyfluorfen + oryzlain at 12 lb a.i./acre caused severe phytotoxicity (≈80% to 95% of plant injured) and stunted the growth (70% to 80% less growth, sometimes plant death) of woolly yarrow. Woolly thyme was stunted by all herbicides when applied at the recommended rates (42% to 97% less growth compared to control) except for oxadiazon and oxyfluorfen + oryzlain. Woolly thyme appeared to be more susceptible to phytotoxicity due to its less-vigorous growth habit and shallow, adventitious roots that were in contact with the herbicide.
Fumiomi Takeda, D. Michael Glenn and Thomas Tworkoski
Three experiments were performed to determine the effect of amending the soil surface layer and mulching with hydrophobic kaolin particle on weeds and blackberry (Rubus subgenus Rubus Watson) plants. In the first study a processed kaolin material (product M-96-018, Engelhard Corporation, Iselin, N.J.), was incorporated in August into the top 3 cm of freshly roto-tilled field that had been in pasture the previous 5 years. The following spring, dry weight of weed vegetation in the control treatment was 219 g·m–2 and was significantly higher (P = 0.05) than the 24 g·m–2 harvested from the treated soil. In two other studies, planting holes for blackberry transplants were either 1) pre- or postplant mulched with a 2- or 4-cm layer of 5% or 10% hydrophobic kaolin in field soil (w/w), or 2) postplant treated with a) napropamide, b) corn gluten meal, c) a product comprised of hydrous kaolin, cotton seed oil, and calcium chloride in water (KOL), d) hand weeded, or e) left untreated. Although untreated plots had 100% weed cover by the end of July, herbicide treatments, 4-cm deposition of hydrophobic kaolin particle/soil mulch, and KOL all suppressed weeds the entire establishment year. Preplant application of hydrophobic kaolin mulch and postplant application of KOL reduced blackberry growth and killed transplants, respectively. In year 2, blackberry plants produced more primocanes that were on average 10-cm taller in weed-free plots (herbicide, 4-cm kaolin soil mulch, and mechanical weeding) than in weedy plots (control and 2-cm kaolin soil mulch). In year 3, yield was significantly lower in control plots (1.5 kg/plant) than in plots that were treated with napropamide and 2- and 4-cm hydrophobic kaolin mulch, or hand weeded during the establishment year (4 kg/plant). The results showed that 4-cm hydrophobic kaolin mulch applied after planting can suppress weeds without affecting blackberry productivity. These kaolin products are excellent additions to the arsenal of tools for managing weeds in horticultural crops.
James P. Gilreath, Bielinski M. Santos, Joseph W. Noling, Salvadore J. Locascio, Donald W. Dickson, Erin N. Rosskopf and Steven M. Olson
Field studies were conducted in three Florida locations (Bradenton, Gainesville, and Quincy) during 1998-99 and 1999-2000 to: 1) compare the performance of two transplant systems under diverse MBr alternative programs in `Chandler' strawberry (Fragaria ×ananassa), and 2) determine the efficacy of these treatments on soilborne pest control in strawberry. Fumigant treatments were: 1) nonfumigated control, 2) methyl bromide plus chloropicrin (MBr + Pic) at a rate of 350 lb/acre, 3) Pic at 300 lb/acre and napropamide at 4 lb/acre, 4) 1,3-dichloropropene (1,3-D) plus Pic at 35 gal/acre and napropamide at 4 lb/acre, 5) metam sodium (MNa) at 60 gal/acre and napropamide at 4 lb/acre, and 6) MNa followed by 1,3-D at 60 and 12 gal/acre and napropamide at 4 lb/acre, respectively. Strawberry transplants were either bare-root or containerized plugs. There were no significant fumigant by transplant type interactions for strawberry plant vigor and root weight per plant, whereas ring nematode (Criconema spp.) and nutsedge (Cyperus rotundus and C. esculentus) populations, and total marketable fruit weight were only infl uenced by fumigant application. The nonfumigated plots had the lowest strawberry plant vigor and root weight per plant in all three locations. In most cases, plant vigor and root biomass per plant increased as a response to any fumigant application. With regard to the transplant type, bare-root transplants had similar plant vigor as plugs in two of the three locations. Fumigation improved nutsedge and ring nematode control. All fumigants had higher early and total marketable yield than the nonfumigated control, whereas transplant type had no effect on total fruit weight.
Martin L. Kaps and Marilyn B. Odneal
Nine preemergent herbicides were applied at maximum label rate in Fall 1986, 1987, and 1988 to a `Catawba' grape (Vitis labrusca L.) vineyard in the Missouri Ozark region. The untreated controls showed 30% total weed cover by 28 Apr. 1987, 21 May 1988, and 18 Apr. 1989. In 1988, less rain fell early in the growing season; thus, weed cover in the untreated controls was delayed until late in the season. The herbicides norflurazon, oryzalin, and oxadiazon gave the longest period of acceptable grass control. Dichlobenil, diuron, oxyfluorfen, and simazine gave the longest period of acceptable broadleaf control. Most of the herbicides lost residual activity by early summer. For this reason, fall preemergent herbicide application cannot be relied on to give season-long control the following year in southern Missouri. Chemical names used: 2,6-dichlorobenzonitrile (dichlobenil); N' -(3,4-dichlorophenyl) - N,N -dimethylurea (diuron); N,N -diethyl-2-(1-napthalenyloxy)-propanamide (napropamide); 4-chloro-5-(methylamino)-2-(3-(trifluoromethyl)phenyl)-3(2H)-pyrdazinone (norflurazon); 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5 -(l,l-dimethylethyl) -l,3,4-oxadiazol-2- (3H)-one (oxadiazon); 2-chloro-l-(3-ethoxy-4-nitrophenoxy) -4-(trifluoromethyl) benzene (oxyfluorfen); 3,5-dichloro-N-(l,l-dimethyl-2-propynyl)benzamide (pronamide); and 6-chloro- N,N' -diethyl-1,3,5-triazine-2,4-diamine (simazine).
Grant R. Manning and Steven A. Fennimore
Methyl bromide has been the foundation of chemical weed control in strawberry (Fragaria ×ananassa) in California for over 40 years. The impending phaseout of methyl bromide may leave strawberry producers dependent on less efficacious alternative fumigants for weed control. The use of herbicides to supplement fumigants is a potential weed control strategy for strawberry. A 2-year field study was conducted in California to evaluate 10 herbicides as possible supplements for methyl bromide alternative fumigants. Herbicides were applied immediately after transplanting (immediate posttransplant), and 3 weeks after transplanting (delayed posttransplant). Napropamide applied immediate posttransplant was included as a commercial standard. Immediate posttransplant treatments that were safe in strawberry include carfentrazone at 0.075 and 0.15 lb/acre (0.084 and 0.168 kg·ha-1), flumioxazin at 0.063 lb/acre (0.071 kg·ha-1) and sulfentrazone at 0.175 and 0.25 lb/acre (0.196 and 0.28 kg·ha-1). Triflusulfuron at 0.016 lb/acre (0.017 kg·ha-1) was the only delayed posttransplant treatment with acceptable selectivity. Among the selective herbicides applied immediate posttransplant, flumioxazin and napropamide provided the most consistent control of bur clover (Medicago polymorpha) and shepherd's purse (Capsella bursa-pastoris). Triflusulfuron applied delayed posttransplant did not significantly reduce bur clover densities, but did reduce shepherd's purse densities.
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).