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- Author or Editor: David E. Yarborough x
One hundred lowbush blueberry (Vaccinium angustifolium Ait.) clones were randomly sampled from a commercial field to estimate potential productivity. Yield data exhibited a normal distribution ranging from 300 to 17,000 kg·ha-1 with a mean of 7726 kg·ha-1. Commercial use of selected clones or improved cultivars through new plantings, interplanting into existing clones, or replacement of low-yielding clones in native stands and increasing the intensity of field management would increase the yielding potential of native lowbush blueberry fields.
Three hundred, 1 m2 plots with either 0%, 25%, 50%, 75% or 100% dogbane or bracken fern weed cover were used in the study. The experimental design was completely randomized with two species, three treatments (mow, wipe and untreated), five densities and 10 replications. One half of each plot had weed cover and one half was kept weed free in order to compare the effect of weed density on yield. Plots were treated with either 10% v/v glyphosate in a hand held weed-wiper, mowed with a string trimmer or left untreated. Wiping was more effective than mowing for reducing weed numbers in the following year. However, wiping reduced yields compared to mowing at higher weed densities. Mowing proved more effective at increasing yields up to 50% weed cover compared to wiping or not treating. Averages from 1991 and 1992 study indicate mowing increases yields compared to wiping up to 50% then tend to decline, but yields remain greater than not treating.
Abstract
Hexazinone was applied preemergent, after pruning, at 1.1, 2.2, 4.5, or 9.0 kg/ha to a commercial lowbush blueberry (Vaccinium angustifolium Ait.) field. Visual ratings indicated a quadratic decline in grasses and a linear increase in blueberry injury associated with hexazinone application. Counts of weed populations showed a highly significant linear decline in meadowsweet (Spiraea latifolia Borkh.) and goldenrod (So-lidago sp.) with an increase in hexazinone rate. Hexazinone treatments did not affect the density of blueberry stems, but flower buds and yield followed a quadratic trend. Hexazinone provided excellent control of many common weed species accompanied by a significant increase in blueberry yield. Chemical name used: 3-cyclohexyl-6-(di-methylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione (hexazinone).
The competitive effects of bunchberry Cornus canadensis L. on native stands of blueberries Vaccinium angustifolium Ait. was assessed in 1986 and 1987, and in the greenhouse in 1987 with replacement series experiments. In the field, blueberry and bunchberry fruit were harvested in August and all aboveground growth was cut, the species were separated, and dry weight was determined. The relative yield total (RYT), defined as the dry weight (DW) of the combined aboveground portions of the blueberry and bunchberry divided by their respective DW at 100% cover, was >1 and showed an increase with increasing proportion of bunchberry. Blueberry relative yield, defined as the DW of the aboveground portion divided by the DW at 100% cover, was >1, but bunchberry relative yield DW was ≤1. Regression of individual on associate DW yield indicates blueberry is as aggressive as bunchberry. Blueberry fruit count and yield decreased with increasing bunchberry density. In the greenhouse study, plant count and cover were assessed weekly, and leaf area index (LAD and DW were obtained at the end of the study. RTY > 1, and combined DW increased with increasing proportion of bunchberry. The LAI of blueberry or bunchberry was higher in mixtures than in pure stands. Blueberries are competitive with bunchberry, but in native fields, open areas among clones allow faster growing bunchberry to spread without competition.
Abstract
No differences in plant stand, stem length, growth habit, flower bud formation or yield were detected between fall vs. spring or between mechanical vs. thermal pruning (burning with oil) of lowbush blueberries Vaccinium angustifolium Ait. This suggests that close flail mowing may be an acceptable alternative to burning for pruning lowbush blueberries.
An experiment was established to compare open mineral soil, soil with bark mulch, soil with blueberry cover and tilled clones on hexazinone movement through the soil. Hexazinone was applied preemergence to a lowbush blueberry field at 2 kg/ha in the spring of 1990 and soil samples were taken at the time of application, one month, six months and one year after application at a depth of 0-5 cm, 5-15 cm and 15-25 cm. At the time of initial application, the mulched plots had twice the amount of hexazinone as the others. The hexazinone concentration after one month shows the concentration of hexazinone decreased with an increase in depth, with the open areas having the highest levels of hexazinone. It appears that the hexazinone has moved down through the soil column with the higher concentrations above and lower concentrations below. The data indicate that the hexazinone decreased rapidly in the first month, and then declined by about half over each 6 months thereafter. It appears that there is less hexazinone in the lower layers of the soil and that the open areas had the highest concentration at one month but the levels equal out over time.
Abstract
Effects of selective contact application of 2,4-dichlorophenoxyacetic acid (2,4-D) or N-phosphonomethylglycine (glyphosate) on a mixed stand of blueberry (Vaccinium angustifolium Ait.) and barrenberry (Aronia melanocarpa (Michx.) Ell.) were studied using a selective herbicide applicator. The greater height of barrenberry in its second year of growth provided the selectivity. Herbicide application on the burn year reduced both blueberry and barrenberry plant stands. Selective application of glyphosate or 2,4-D reduced the number of barrenberry plants without seriously affecting blueberry plant stem length or fruit bud number when applied to crop year plants after harvest. Higher rates of herbicides resulted in a greater reduction in barrenberry plant stand. Glyphosate or 2,4-D provided adequate control of regrowth of black barrenberry plants in lowbush blueberry fields.
Abstract
N-(phosphonomethyl)glycine(glyphosate) or 2,4-D (2, 4 dichlorophenoxy)acetic acid (2, 4-D) was applied on 2 dates (October 28 or November 10) after leaf abscission of blueberry (Vaccinium angustifolium Ait.) in a commercial field containing lambkill (Kalmia angustifolia L.); plots were thermally pruned the following spring. Lambkill plant stand decreased with increasing rates of glyphosate or 2, 4-D. A late application of glyphosate was more effective than 2, 4-D in reducing lambkill plant stand. Increasing the rate of glyphosate resulted in a greater number of blueberry stems, more flower buds per stem, and a higher yield. Glyphosate applications reduced the length of reemerging lambkill stems but 2, 4-D did not. Glyphosate was as effective in reducing lambkill plant stand at 2.2 kg/ha as 2, 4-D was at 4.5 kg/ha.
Abstract
A greenhouse study was conducted to investigate the herbicidal effects of N-phosphonomethylglycine (glyphosate) and 2,4-dichlorophenoxyacetic acid (2,4-D) on black barrenberry Aronia melanocarpa (Michx.) Ell. Phytotoxicity symptoms were more evident and regrowth was less in plants receiving 2,4-D than those treated with glyphosate. Placement of herbicides on all foliage caused more visual injury than placement on half the foliage but did not influence survival. Higher rates of both herbicides resulted in more injury and reduction in plant survival than the lower rates.
Abstract
The economic feasibility of using hexazinone for weed control in lowbush blueberries (Vaccinium angustifolium Ait.) was determined by using the partial budgeting technique. Four rates of hexazinone were evaluated to determine the effect on net income in a blueberry enterprise. Response function analysis also was utilized to ascertain the hexazinone level that would maximize blueberry yield and profitability. Partial budget analysis indicated that hexazinone use at 1.1, 2.2, and 4.5 kg/ha was expected to increase net income, indicating its use was economically feasible. Hexazinone use at 9 kg/ha was judged to be economically infeasible, since it decreased net income. Response function analysis revealed that 2.3 kg/ha of hexazinone maximized profits. Chemical names used: 3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-tria-zine-2,4(1H,3H)-dione (hexazione).