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  • Author or Editor: C. Edward Beste x
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Abstract

Two annual applications of oxyfluorfen (2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene), oxadiazon (2-tert-butyl-4(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one) or prodiamine (2,4-dinitro-N3,N3-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine) at 4.5 kg/ha controlled 80% of the weeds in several cultivars of newly-planted or established azaleas. Significant early season injury was observed in 1980 on ‘Hershey Red’, ‘Hinocrimson’, and ‘Delaware Valley White’ azaleas treated with DCPA (dimethyl tetrachloroterephthalate) at 11.2 kg/ha. Established ‘Hinocrimson’ azaleas treated with oxyfluorfen at 4.5 kg/ha were significantly larger than the control plants at the end of these experiments.

Open Access

Abstract

A single postemergence application of sethoxydim at 0.5 or 1.0 kg a.i./ha or fluazifop at 1.0 kg a.i./ha controlled established seedlings of slender foxtail (Alo-pecurus myosuroides Huds.) and large crabgrass [Digitada sanguinalis (L.) Scop.] in field-grown Rhododendron obtusum (Lindl.) Planch ‘Delaware Valley White’, ‘Hinocrimson’, and ‘Hershey Red’ azaleas. No significant phytotoxicity symptoms were observed on ‘Delaware Valley White’ or ‘Hershey Red’ azaleas, but ‘Hinocrimson’ azaleas treated with fluazifop at 0.50 or 1.0 kg a.i./ha were significantly injured for up to 82 days. The growth of ‘Hinocrimson’ azaleas also was reduced significantly when observed 82 days after treatment with fluazifop at 0.25, 0.50, or 1.0 kg a.i./ha or sethoxydim at 1.0 kg a.i./ha. ‘Hinocrimson’ azaleas treated with a single application of fluazifop at 1.0 kg a.i./ha were significantly smaller 15 months after treatment. Chemical names used: 2-[l-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclo-hexen-l-one (sethoxydim) and (±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy]phenoxy]propanoic acid (fluazifop).

Open Access

Abstract

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).

Open Access

Potential increases in the yield of agronomic crops through enhanced light interception have led many growers to consider using narrow rows in lima bean (Phaseolus lunatus L.). However, no information is available on how narrow row spacing affects weed management or fits into an integrated pest management strategy. To address this, field studies were conducted in Delaware and Maryland in 1996 and 1997 to evaluate the effects of row spacing (38 vs. 76 cm) on weed control, and on yield and quality of lima bean. Weed management inputs were also evaluated with labeled or reduced pre-emergence rates of metolachlor plus imazethapyr applied broadcast or banded. Only 76-cm rows were cultivated according to the standard practice for this production system. In general, row spacing, herbicide rate, and herbicide application method had no effect on lima bean biomass or yield, on weed density, control, or biomass production, or on economic return. However, weed control consistency was improved when wide rows were used, even with reduced herbicide rates, possibly because of cultivation. Using reduced herbicide rates and band applications resulted in 84% less herbicide applied without affecting weed control. Chemical names used: 3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (bentazon); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl-4-(1-methylethyl)-5-oxo-1Himidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid (imazethapyr); 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 2-[1-(ethoxyimino)butyl]-5-[2-ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one (sethoxydim).

Free access