Progress 10/01/02 to 09/30/07
Outputs
Hexazinone has been the standard herbicide used on Maine wild blueberry (Vaccinium angustifolium) fields for over twenty years and shifts in weed populations have resulted in a lack of control of many weeds. A study to evaluate the effects of the herbicide mesotrione with and without hexazinone was initiated in 2006 and continued in 2007 with harvest of the 2006 blocks, and the addition of six split design blocks on six wild blueberry fields across Maine in order to account for soil type and weed species diversity. Blocks were established in the townships of Union, Northport, Orland, Penobscot, T19, and the Blueberry Hill Experimental Farm in Jonesboro. Each block measured 22 x 29 m and was comprised of four 7 x 22 m mesotrione treatments including 437 mL/ha pre-emergence; 217 mL/ha pre-emergence and post-emergence; 217 mL/ha post-emergence application; and none (untreated control). At right angles to the mesotrione treatments, 1.1 kg/ha hexazinone was applied
pre-emergence to half of each block. In 2007 pre-emergence treatments were applied on May 9 to 11, and post-emergent treatments were applied on June 14 and 15. Blueberry and weed cover, as well as blueberry phytotoxicity, were assessed June 27 to July 9 and on August 17 to 21. Treatment effects were assessed for blueberry, broadleaf weeds, grasses and ferns using a Daubenmire cover scale, and for phytotoxicity as percent injury. Broadleaf weed cover was highest in the untreated control treatment for both evaluations. Mesotrione at 217 mL/ac post-emergence combined with hexazinone suppressed broadleaf weeds more so than other treatments at the June evaluation, but by the August evaluation broadleaf weed cover was not significantly different from any other herbicide treatment. Although amounts of broadleaf weed cover were not statistically different for either evaluation, the combination of hexazinone and mesotrione and/or pre- and post-emergence applications tended to suppress
broadleaf weeds more effectively than a single herbicide or application. Grass cover was highest in the untreated control and the mesotrione 437 mL/ha pre-emergence treatment at the June evaluation, while at the August evaluation the mesotrione 217 mL/ac pre- and post-emergence treatment had the highest grass cover. Grass cover in the mesotrione 217 mL/ac pre-and post-emergence treatment with hexazinone was significantly lower than the former at the June evaluation, but did not differ from the hexazinone, mesotrione 437 mL/ha pre-emergence with hexazinone or 217 mL/ha post-emergence with hexazinone treatments. Grass cover in the hexazinone, mesotrione 437 mL/ha pre-emergence with hexazinone, 217 mL/ha pre-and post-emergence with hexazinone and 217 mL/ha post-emergence with hexazinone were significantly lower than the latter at the August evaluation, but did not differ from each other, the untreated control or remaining mesotrione treatments. Although for the most part the mesotrione
treatments in combination with hexazinone did not significantly suppress grasses compared to mesotrione alone, and overall grass cover increased with time, there was a trend of better grass suppression when both herbicides were applied.
Impacts
Weeds limit yields and reduce quality of wild blueberry harvest. Purpose of this study is to develop chemical and cultural weed management techniques to allow wild blueberries to maintain and improve production efficiency.
Publications
- ASSESSMENT OF THE COMBINED EFFECTS OF MESOTRIONE AND HEXAZINONE ON WEEDS IN WILD MAINE BLUEBERRIES. 2007. D.E. Yarborough and K.F.L. Guiseppe. Proceeding of the Northeastern Weed Science Society. 61:93-94.
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Progress 10/01/05 to 09/30/06
Outputs
Hexazinone has been the principle herbicide used in Maine wild blueberry fields for over twenty years. There is evidence that reliance on hexazinone without other alternative herbicides has resulted in increased populations of grasses and other herbaceous weeds. There is a need for herbicides with different modes of action for herbicide rotations in wild blueberry fields. In order to evaluate the herbicide mesotrione with and without hexazinone a split block design was established on six wild blueberry fields throughout the state to obtain a diversity of soil types and weed species. A block was established in the Maine towns of Union, Belfast, Penobscot, Orland, Town ship 19 and at the Blueberry Hill Experimental Farm in Jonesboro. A 16 x 20 m block was comprised of 4 X 16 m treatment plots including an untreated control, mesotrione at 444 ml/ha pre-emergence, 222 ml/ha pre-emergence and 222 ml/ha post-emergence on the same plot, and 222 ml/ha post-emergence. At right
angles on an 8 X 20 m plot of either an untreated control or a hexazinone treatment at 1 kg/ha was applied to give a total of eight combinations. Pre-emergence treatments were sprayed on 8-11 May. Postemergence treatments were sprayed on 6-9 June. Treatment effects were assessed for broadleaf, fern and grass weed cover using a Daubenmire cover scale and wild blueberry phytotoxicity as percent injury from four 1m square subplots within each treatment. The first weed cover evaluation was on June 19 and 23 and the second was on August 14 and 23, 2006. A carryover weed control assessment and yield samples were taken from the six sites treated in 2005. Weed assessment occurred on June 19 and 23. Plots were harvested using four 1m square subplots within each treatment and weights are in pounds per plot. Blocks were harvested on 26 July to 3 August. The mesotrione applications at the higher rate preemergence or at the low rate pre and post emergence gave equivalent control to the hexazinone
application. When these applications were combined with hexazinone additional suppression of both grasses and broadleaf weeds was obtained. These treatments, except for the post emergence flumioxazin resulted in higher yields than the control and equivalent yields to the hexazinone standard treatment. Mesotrione may be used alone or in combination to provide weed suppression and increase in yields in lowbush blueberries.
Impacts
Weeds limit yields and reduce quality of wild blueberry harvest. Purpose of this study is to develop chemical and cultural weed management techniques to allow wild blueberries to maintain production efficiency.
Publications
- Perkins, B. L., D. Yarborough, K. Guthrie, and R. Bushway. 2006. Detection of Hexazinone in Maines Groundwater- A Nine Year Study. Acta Horticulturae 715:329-335, MAFES 2708.
- Starr, G. C. and D. E. Yarborough. 2006. Influence of Vapor Deposition on Wild Blueberry Water Requirements in a Humid Coastal Climate. Acta Horticulturae 715:323-328, MAFES 2706.
- Yarborough, D. E. 2006. Innovations in Weed Management in Wild Blueberry Fields in Maine. Acta Horticulturae 715:197-202, MAFES 2701.
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Progress 10/01/04 to 09/30/05
Outputs
Hexazinone is a widely used herbicide, which has contributed to increases in the production of wild blueberries (Vaccinium angustifolium) in Maine since 1982. But since it is very soluble, it has been detected in groundwater adjacent to blueberry fields and throughout the state. Therefore alternative herbicides are needed to control local these weed populations and to maintain productivity of Maine wild blueberry production. A split block design was established on six wild blueberry fields to obtain a diversity of soil types and weed species. Six, 120 x 72 ft, blocks was comprised of 24 X 36 ft treatment plots including an untreated control, a pre and post-emergence application of mesotrione at 6 oz/a and a pre and post-emergence application of flumioxazin at 12 oz/a. At a right angle a 36 X 120 ft plot of an untreated control and a hexazinone treatment at 64 oz/a was applied to give a total of ten combinations. Preemergence treatments, including the hexazinone
treatment applied in late May or early June and postemergence treatments that were applied mid June. A soil sample was taken at each site and the Maine Soil Testing Laboratory at the University of Maine determined soil texture, OM and pH. Evaluation of blueberry cover and phytotoxicity, herbaceous weeds, grasses and ferns were made using a Daubenmire cover class scale on 27 June and 26 August. Data were transformed to percent cover and analyzed by the General Linear Model of SAS with significant means separated by a Duncans multiple range test. Blueberry cover was significantly reduced by the high phytotoxicity observed on the post-emergence treatments. Grass cover was higher in the untreated control than all treatments at the June evaluation but not the August evaluation. In June, all applications reduced grass cover, but significant additional suppression was obtained with the addition of hexazinone to the flumioxazin and mesotrione treatments, with the best suppression obtained
with the post-emergence application of flumioxazin. The use of hexazinone also significantly reduced the amount of grass and broadleaf weed cover in the June evaluation. Although broadleaf weed cover was initially reduced after pre and postemergence applications in June, except for the preemergence mesotrione application, the cover of postemergence mesotrione was higher than the control in the August evaluation. The addition of hexazinone to both herbicide treatments further reduced the broadleaf cover, though not significantly. Neither flumioxazin nor mesotrione reduced fern cover without Hexazinone, but the addition of hexazinone to either herbicide treatment reduced fern cover with the exception of the post-emergence mesotrione treatment for the August evaluation. The postemergence flumioxazin application had the lowest fern cover. These herbicides were evaluated at Blueberry Hill Farm in Jonesboro, Maine last year and no phytotoxicity was seen on blueberry plants with their
post-emergence treatments. The unusually cold and wet weather Maine experienced throughout the spring months may have increased the susceptibility of the blueberries to the herbicides.
Impacts
Alternative herbicides and methods of application are being evaluated for rotation in order to lessen the industry's reliance on a herbicide that is found in groundwater
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
Hexazinone has been the principle herbicide used in wild blueberry fields since 1982. Its use has contributed to a four fold wild blueberry yield increase over the past 20 years. Hexazinone, which is highly leachable and easily detectable, has been found in groundwater throughout the state in and adjacent to wild blueberry fields. In addition, annual grass populations and herbaceous weeds such as bunchberry have been increasing with the use of hexazinone. Several alternative herbicides have been evaluated for rotation with hexazinone, but materials have either been ineffective or not registered, as in the case of azafenidin. Alternative herbicides are needed to prevent build up of these weed populations and to reduce the reliance on hexazinone. The trial experimental design was a randomized, complete block design with six replicates and was conducted at Blueberry Hill Farm Research Station in Jonesboro, Maine. Herbicides evaluated include hexazinone as the standard at
1 kg/ha, flumioxazin at 0.9 kg/ha and mesotrione at 148, 222 or 444 ml/ha as well as an untreated check plot. Hexazinone and flumioxazin were applied pre-emergence on 10 May. Mesotrione was applied preemergence on 13 May 2004 and post-emergence on 9 June 2004. Evaluation of blueberry cover, herbaceous weeds, grasses and ferns were made using a 1-6 Daubenmire cover class scale on 23 June and 18 August 2004. Data were transformed to percent cover and analyzed by the General Linear Model of SAS with significant means separated by a Duncans multiple range test. No significant reductions in cover or phytotoxicity of wild blueberries were noted for any of the treatments. Broadleaf cover averaged less than 20 percent and although some treatments were less than the untreated or hexazinone standard, several were greater but none were statistically significant. Grass cover appeared to be released, with the post flumioxazin and mesotrione treatments having an increase in cover. Fern cover also
increased with the highest rate of both flumioxazin and mesotrione treatments but the effect was not significant. In all cases the hexazinone standard and check plot were not significantly different. Additional trials with larger plots on more locations are planed to further evaluate the potential of these herbicides.
Impacts
Alternative herbicides and methods of application are being evaluated for rotation in order to lessen the industrys reliance on a herbicide that is found in the groundwater.
Publications
- Yarborough D.E. and K. Lough. 2004. Comparison of clean-cut vs Wiping and Cutting for Weed Control in Wild Blueberries. Proceedings of the Northeastern Weed Science Society. 58:143-144.
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Progress 10/01/02 to 09/30/03
Outputs
In the summer of 2003, a clean-cut adapter on hand clippers and a wiper were evaluated for their effectiveness in reducing woody and herbaceous weeds. The clean-cut adaptor consists of an attachment that dispenses a thin film of herbicide on the blade of a hand-clipper, which is drawn into the roots of weeds as they are cut. A control and five treatments were applied to grey birch (Betula populifolia), braken fern (Pteridium aquilinum) and dogbane (Apocynum androsemifolia) stems, each treatment was applied to ten separate stems. Treatments include stems cut once without herbicide, stems cut with 100% glyphosate (Touchdown 5 formulation), stems cut with 100% glyphosate with 2% w/v ammonium sulfate, stems wiped with a 20% v/v solution of glyphosate, and stems wiped with a 20% solution of glyphosate with 2% ammonium sulfate. Treatments were applied 27 June on bracken fern and dogbane stems at Blueberry Hill Experimental Farm in Jonesboro, ME and on 2 July on birch stems
in a commercial wild blueberry field in T-18 MD, ME. In September 2003, each stem was rated for vigor and phytotoxicity of the adjacent wild blueberry plants was recorded. Results indicate the five treatments reduced the growth and survival of all three species compared to the control. For both dogbane and birch, cutting alone did not significantly reduce the survival of the weeds as well as the cutting with the herbicide or wiping alone or with the ammonium sulfate. There were no differences in the survival of either the woody or herbaceous weeds based on the type of application, or if ammonium sulfate was included. Application of the herbicide with the wiper resulted in more phytotoxicity to wild blueberries than with the clean-cut adapter on hand clippers for both the ferns and the dogbane, but not for the birch. A follow-up evaluation is planned for 2004 to determine the continued effectiveness of the treatments.
Impacts
Alternative herbicides and methods of application are being evaluated for rotation in order to lessen the industrys reliance on a herbicide that is found in the groundwater.
Publications
- Dalton, T.J., A. Files, and D.E. Yarborough. 2003. An Economic Assessment of the Returns to Irrigation Investment for Wild Blueberries. Acta Horticulturae. 626: 249-257.
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