Abstract
During 1978 and 1979, oxadiazon [2-ferf-butyl-4-(2-,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazolin-5-one] and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] were evaluated on 7 species of container-grown ornamentals for full season weed control, phytotoxicity, and final plant size. Based on these experiments, both herbicides provided 75% or better weed control for a 4 month period when applied at recommended and higher rates. Neither herbicide caused any significant plant injury to the 7 species when applied at 4 times the recommended rate. The largest plants were produced in containers treated with the herbicide rates providing the best weed control, and also in the weeded controls.
Abstract
A 3-step method for weed control in onion seed fields is described which involves early spring tillage to kill winter-annual weeds; mid-spring tillage plus a preemergence herbicide to kill spring-annual weeds and a directed herbicide spray at layby time to kill the summer-annual weeds. The method gave nearly complete season-long weed control on experimental plots as well as commercial onion seed fields.
Abstract
In order to reduce the cost of fumigation and weed control in seedling nurseries of peach (Prunus persica (L.) Batsch.), a number of herbicides, used with and without Nemagon as a nematicide, were evaluated. While necessary for soil fumigation, the presence or absence of Nemagon did not effect weed control or seedling performance. The best and most economical herbicides were the spring application of simazine at 4.5 kg ai/ha or the fall application of diuron at 3.4 kg ai/ha.
Abstract
Hoeing and glyphosate (N-(phosphomomethyl)glycine) application with a hand-held wiper were compared for weed control in mixed vegetable plantings. Weed control with wiper-applied glyphosate required significantly less labor and expense than hoeing. Vegetable yields were similar in hoed and wiper-weeded plots and both methods increased the yields of some vegetable species over yields from unweeded plots. Yellow nutsedge (Cyperus esculentus L.) shoot populations were reduced significantly by wiper weeding but not by hoeing.
Flumioxazin (Chateau 51WG) is an herbicide for the preemergence and early postemergence control of broadleaves and grasses. Chateau was recently labeled for use in non-bearing fruit trees and bearing grapes. Long-term weed control in apple, peach, and blueberry was investigated following fall application of herbicides. Treatments consisted of simazine 2.8 kg a.i., norflurazon 2.24 kg a.i., napropamide 2.24 kg a.i., and oryzalin 2.24 kg a.i. were applied on 11 Nov. 2003. Flumioxazin was also applied at 0.1 and 0.43 kg ai on apple and peach. All treatments included glyphosate 1 lb a.i. for burndown control of preexisting weeds. Weed control evaluation in mid-April or 4 months after application showed that flumioxazin-treated plots had no weeds present and no weed regrowth. Plots treated with napropamide, norflurazon, and oryzalin showed significant regrowth of dandelion, common ragweed, and chickweed. Simazine plots had fewer weeds germinating than the other herbicides. By early June or 6 months after application, no differences in residual weed control were observed for all treated plots when compared to the control. All plots were equally weedy and required immediate floor management measures. It appears that flumioxazin weed control benefit was exhausted by 6 months after application, compared to 4 months for all other herbicides. Fall application of flumioxazin can eliminate the need for early spring weed control. This time saved can be spent on other important activities such as pruning and disease and insect control.
Alternative approaches to strawberry production that rely on cultural practices, biological controls, or natural products to reduce or replace off-farm chemical inputs are needed. Driving this growing interest are environmental concerns and rising production costs. Corn gluten meal (CGM), a byproduct of corn wet-milling, has weed-control properties and is a N source. The weed control properties of CGM have been identified in previous studies. The hydrolysate is a water-soluble, concentrated extract of CGM that contains between 10% to 14% N. Our objective was to investigate corn gluten hydrolysate as a weed control product and N source in `Jewel' strawberry production. The field experiment was a randomized complete block with a factorial arrangement of treatments and four replications. Treatments included application of granular CGM, CGM hydrolysate, urea, urea, and DCPA (Dacthal), and a control (no application). Granular CGM and urea were incorporated into the soil at a depth of 2.5 cm at rates of 0, 29, 59, and 88 g N/plot. Plot size was 1 × 3 m. The field experiment was conducted from 1995-1998. The source of nitrogen showed few effects for all variables measuring yield and weed control for all years. In general, the rate of nitrogen had little or no effect on total yield. However, the rate of nitrogen at 88 g N/plot showed an increase in average berry weight, leaf area, leaf dry weight, and weed control.
Abstract
Growth of 2-year-old tart cherry (Prunus cerasus L.) trees as measured by trunk circumference increase or total shoot elongation was significantly greater in plots receiving chemical or mechanical weed control within the tree row than in plots receiving between-row cultivation only. Shoot growth of one-year-old apple (Malus domestica Borkh. ‘Delicious’) trees responded similarly to weed control. Tart cherry trees in hand weeded and dinoseb or glyphosate treated plots had greater growth than those in paraquat treated plots. Tart cherry trees in plots receiving chemical or mechanical weed control out-yielded trees in unweeded plots during the first year of production. ‘Delicious’ apple trees in plots treated with dinoseb (6.7 and 10.1 kg/ha), the high rate of glyphosate (1.7 kg/ha), or mechanical weed control also outyielded trees in unweeded plots during the first year of production. Effects of weed control on growth and yield were less distinct during the 2nd year of production. Trees from treated plots came into production one year earlier than trees in the unweeded plots. Chemical names used: 2-(1-methylpropyl)-4,6-dinitrophenol (dinoseb); N-(phosphonomethyl)glycine (glyphosate); 1,1′-dimethyl-4,4′-bipyridinium ion (paraquat).
Abstract
The efficacy and economics of several weed control systems for fresh market tomato (Lycopersicon esculentum Mill. ‘Pik Red’) production were compared in a 3-year field experiment. Nearly perfect weed control for 7 weeks after transplanting was required to achieve maximum yields. The increased profits associated with maximum yields more than compensated for the additional costs required to achieve optimal weed control. Under Maryland conditions, black polyethylene mulch in combination with a pretransplant incorporated application of napropamide plus pebulate and a posttransplant directed application of paraquat plus metribuzin provided the most consistent weed control and highest profit. Other profitable treatments included black polyethylene mulch in combination with other posttransplant herbicides, or with cultivation and handweeding. Treatments without black polyethylene, including a pretransplant incorporated application of napropamide plus pebulate followed by a postransplant application of metribuzin and/or cultivation, provided good weed control but did not result in yields or profits as high as those treatments with black polyethylene in 2 out of 3 years.
Hybrid poplar is traditionally established using dormant stem cuttings in tilled soils followed by chemical or mechanical weed control. In 1996, we initiated a study to evaluate the effects of site preparation and four weed control treatments on growth and morphology of three hybrid poplar clones established on a 0.2-ha tall fescue field in southern Illinois. Site preparation included application of 2000 kg/ha of 12N-12P-12K. The experiment was arranged as a split-split plot. Main plots were closely mowed tall fescue or tilled to remove the grass sod. Within each main plot, weed control treatments were applied to 1-m wide strips in rows 2.4 m apart. Weed control treatments included porous black film, solid black film, and solid white film, and a control treatment of 3.7 L/ha of glyphosate applied each spring. On 15 Apr. 1996, three 25-cm-long dormant stem cuttings from each of three clones were randomly planted 15 cm deep every 1.8 m within each row. Clonal differences existed after the first year for survival, number of stems, stem height, stem basal diameter, and stem volume, but not for number and total length of lateral branches. Nearly all tree growth measurements analyzed during the first 3 years had a highly significant interaction between type of site preparation and method of weed control. With polyethylene films, tree survival exceeded 90% on both the tilled ground and grass sod sites after 3 years; however, with the herbicide treatment survival averaged only 18% in the grass sod and 51% in tilled soil. Excluding the herbicide treatment, tree growth was better in the grass sod than in the tilled soil. Tree growth using porous black polyethylene film was usually less than that with either of the two solid polyethylene films. The best tree growth was found with a grass sod and solid white polyethylene film for weed control.
Black polyethylene mulch and weed control strategies were evaluated for potential use by small acreage herb producers. In both 1988 and 1989, the mulch greatly increased fresh and dry weight yields of basil (Ocimum basilicum L.) and rosemary (Rosmarinus officinalis L.). Parsley (Petroselinum crispum Nym.) yield did not respond to the mulch. Preplant application of napropamide provided weed control for 2 weeks, but was subsequently not effective on a heavy infestation of purslane (Portulaca oleracea L.). Hand-hoed and glyphosate-treated plots (both with and without plastic) produced equivalent yields. Chemical names used: N, N -diethyl-2(1-napthalenoxy)-propanamide (napropamide); N- (phosphonomethyl) glycine (glyphosate).