Progress 10/01/07 to 09/30/12
Outputs
OUTPUTS: Fine leaf sheep fescue (Festuca filiformis) is an introduced perennial grass in Maine wild blueberry fields, and growers in the Jonesport, ME area recently reported an herbicide-resistant population that has begun taking over local fields. In the first study, herbicides registered for use on wild blueberry as well as unregistered herbicides were evaluated for control of fine leaf sheep fescue and other weeds, and injury to blueberry. Kerb 50W (2 lb/a) was applied in fall 2011 and pre-emergence in spring 2012. Sinbar WDG (2 lb/a)/Direx 4L (2 lb/a)/Velpar L (1 lb/a) or Trimix, Matrix SG (4 oz/a) and Lorox DF(2 lb/a) were also applied pre-emergence, and Arrow (8 oz/a) and Option (1.5 oz/a) were applied twice post-emergence. Fall Kerb resulted in the highest blueberry cover. Lorox and Option had significantly higher initial phytotoxicity but overall levels were not unacceptably high, and the plants grew out of it with the exception of minor phytotoxicity in August in the Lorox treatment. The Trimix was most effective on broadleaf weeds, while Option was the least effective. Fall Kerb was also significantly and consistently most effective in controlling fine leaf sheep fescue over time, followed closely by Matrix, while Arrow and Lorox were consistently ineffective. In conclusion, fall application of Kerb and pre-emergence application of Matrix controlled fine leaf sheep fescue, and Trimix could be effective with low fine leaf sheep fescue pressure. Arrow, Lorox, and spring application of Kerb and Option were not effective if there is sheep fescue and/or broadleaf weed pressure. Combinations of Sinbar with other herbicides continue to be evaluated for weed control and injury to blueberry, in order to develop combinations with different modes of action that will prevent development of weed resistance. Combinations of Sinbar WDG, Velpar L, Direx 4L, Lorox DF, and/or Callisto (6 oz/a) were applied pre-emergence and compared to the check and Velpar L alone. Blueberry cover was comparable over time and there was little phytotoxicity. Sinbar alone and in combination with Lorox and/or Direx did not control broadleaf weeds as well as Velpar, and Sinbar+Lorox+Velpar only resulted in control equal to just Velpar alone. Sinbar+Callisto did not control late season broadleaf weeds. Grass pressure was low, but all treatments except Sinbar+Lorox and Trimix significantly reduced grasses compared to the check or Velpar. In summary, Sinbar+Lorox did not control of broadleaf weeds and/or grasses, but did if Velpar is added. Sinbar+Callisto will control broadleaf weeds and grasses, but an additional post-emergence broadleaf weed herbicide may be needed to control late season weeds. PARTICIPANTS: Participants include the growers who allowed us use of their land for experimental plots. TARGET AUDIENCES: Target audiences include the 575 wild blueberry growers who have farms in the State of Maine and growers in New Hampshire and Massachusetts. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Maine has 575 wild blueberry growers that produce an average of 80 million pounds per year. Maine produces 15 percent of the North American blueberry crop and 40 percent of the wild blueberry crop. Maine has the two largest fruit farms in the US, with two companies exceeding ten and fifteen thousand acres. However, approximately half of the wild blueberries are produced by small growers with an average farm size of 87 acres, but 80% of the growers have operations that are less than 50 acres in size. Maine has the only Agricultural Experiment Station in the US that does research on wild blueberries. Because weed and disease issues continue to evolve research is needed to develop the tools our wild blueberry growers need to provide good weed and disease control in order to maintain yields. Resistance to weeds and diseases will occur if pesticides with the same mode of action are used over time, so there is a need to develop alternatives and use patterns and to be integrated with cultural management to prevent this from happening. Resent research has provided cultural management tools and new organic and reduced risk pesticides but the best use patterns need to be determined and new materials evaluated as weeds and diseases evolve under the selection pressure of existing management. Successful adoption of these practices will insure that wild blueberry growers in Maine can produce a crop efficiently and remain competitive in the world marketplace in future years.
Publications
- Yarborough, D.E. and J.L. D Appollonio. 2012. Preemergent Combinations of Herbicides for Weed Control in Wild Blueberry Fields. Proceedings of the Northeastern Weed Science Society. 66:77.
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: A study to assess the effects of pre-emergence herbicide combinations on wild blueberry cover, phytotoxicity, and broadleaf and grass weed cover was conducted using an RCBD design with 6 replications, treatments included a check, the industry standard Velossa as hexazinone 1 lb/a + surfactant 1 qt/a Sinbar as terbacil 2 lb/a, terbacil 2 lb/a + Callisto as mesotrione 6 oz/a, terbacil 2 lb/a + Matrex as rimsulfuron 4 oz/a, terbacil 2 lb/a +Lorox as linuron 2 lb/a, terbacil 2 lb/a + linuron 2 lb/a + Direx as diuron 2 lb/a, terbacil 2 lb/a + Velpar as hexazinone 1 lb/a + diuron 2 lb/a, Sandea as halosulfuron 1 oz/a, rimsulfuron 4 oz/a, and Allion as indaziflam at 5 and 10 oz/a. The treatments were applied on 18 May 2011 and plots were evaluated approximately 1, 2 and 3 months post-treatment. All data were analyzed using a nonparametric median two-sample exact test with α=0.05. The Sinbar/Velpar/Direx treatment was most effective in controlling weeds without high phytotoxicity. The Sinbar/Lorox/Direx treatment was comparable to the above and could be a viable alternative to Velpar use if Lorox is registered for use on wild blueberry. The Alion and Sandea treatments resulted in unacceptably high phytotoxicity by setting the blueberry plants back, but this may be due to the late application timing as applications in a previous year and an application on another site had much less phytotoxicity. The study will be continued in 2012 to evaluate blueberry yield. PARTICIPANTS: David Yarborough was PI and Jenniffer D Appollono provided technical support. TARGET AUDIENCES: Target audience was 600 wild blueberry growers in Maine. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This study illustrated there are several possible combinations with and without hexazinone, that are both currently registered and in development, which may be used in rotation to effectively control weeds and reduce herbicide resistance without significant injury to wild blueberries.
Publications
- Yarborough, D.E. and J.L. DAppollonio. 2011. Effects of preemergence herbicides for controlling weeds in wild blueberry. Proceedings of the Northeastern Weed Science Society. 65:65.
- Yarborough, D.E. and J.L. DAppollonio. 2011. Effects of postemergence herbicides for controlling weeds in wild blueberry. Proceedings of the Northeastern Weed Science Society. 65:66.
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: A study to assess the effects of pre-emergence herbicides on wild blueberry cover, phytotoxicity and broadleaf and grass weed cover was conducted in spring/summer 2010 using an RCBD design with 6 replications: a check, hexazinone, hexazinone + surfactant, indaziflam, terbacil WP, terbacil WDG, terbacil WDG + mesotrione, pendimethalin and rimsulfuron were applied on 11 May 2010. Plots were evaluated at one, two, four and eight weeks post-treatment and were analyzed using a nonparametric median two-sample exact test PR<0.05. Treatments were compared individually to the check, to the standard hexazinone and to each other where relevant. Hexazinone significantly reduced broadleaf weeds in comparison to the check and did not injure wild blueberry. Hexazinone resulted in lower grass cover than hexazinone at week one only. Addition of the adjuvant resulted in a non-significant reduction of blueberry cover over time and a non-significant increase in broadleaf weeds and grass by eight weeks post-treatment. The indaziflam treatment had significantly lower blueberry cover at one, two and eight weeks post-treatment compared to the check and at one and eight weeks post-treatment compared to hexazinone. Both indaziflam treatments had significantly reduced broadleaf weed cover compared to the check by eight weeks post-treatment, while indaziflam was lower than hexazinone at week one only. The indaziflam treatments also resulted in significantly lower grass cover than hexazinone by eight weeks post-treatment. There was higher blueberry phytotoxicity in the indaziflam treatment than the check or the treatment at four weeks post-treatment, but lower phytotoxicity than the post-emergence treatment at two, four and eight weeks. All terbacil treatments resulted in comparable blueberry cover compared to no treatment or hexazinone, as well as negligible phytotoxicity. Terbacil WDG, alone and with mesotrione, significantly suppressed broadleaf weeds by eight weeks post-treatment compared to no treatment. All terbacil treatments significantly reduced grass cover compared to hexazinone at four and eight weeks post-treatment. Tank-mixing terbacil WDG with mesotrione did not significantly improve broadleaf weed or grass control compared to terbacil WDG alone. Terbacil WDG had significantly more blueberry cover than terbacil WP at four weeks post-treatment, and significantly less broadleaf weed cover than terbacil WP at four and eight weeks post-treatment. Otherwise, there were no significant differences in any cover or phytotoxicity for terbacil WDG versus terbacil WP or terbacil WDG + mesotrione. There were no significant differences between rimsulfuron and the check or hexazinone for blueberry cover or phytotoxicity. At four weeks post-application there was significant phytotoxicity in the pendimethalin treatment, which resulted in significantly lower blueberry cover than the check or hexazinone at week eight. Pendimethalin significantly reduced broadleaf weeds by eight weeks compared to the check. Grass cover in the pendimethalin treatment was significantly lower than hexazinone by week eight, and rimsulfuron had lower grass cover at weeks four and eight. PARTICIPANTS: David Yarborough was PI and Jenniffer D Appollono provided technical support TARGET AUDIENCES: Target audience was 600 wild blueberry growers in Maine PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
This study illustrated there are several viable options to Velpar, both currently registered and in development, that may be used in rotation to effectively control weeds without significant injury to wild blueberries.
Publications
- Yarborough, D.E. and J.L. D Appollonio. 2010. Spot treatments of broadleaf weeds and grasses in wild blueberry fields using a mesotrione/clethodim tank mix. Proceedings of the Northeastern Weed Science Society. 64:13.
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: A spot treatment trial was conducted to assess the efficacy of a mesotrione/clethodim tank mix in controlling broadleaf weeds and grasses in wild blueberry (Vaccinium angustifolium) fields. Twenty 1 by 4 m plots each were located on non-crop fields at Blueberry Hill Farm (BBHF) in Jonesboro, ME and Jasper Wyman and Son's Burnt Camp Hill lot in Deblois, ME; each plot contained blueberry and similar suites of broadleaf and grass weed species. At each site, ten plots were treated with a handheld spray boom tank mix of mesotrione at 3 oz/a and clethodim at 6 oz/a with a non-ionic surfactant at 0.25% v/v. The BBHF site was treated on 2 June and 10 July, while the Wyman's site was treated on 16 June and 20 July. The Wyman's site was treated later because the weeds at this site were developmentally behind the BBHF site; therefore, the weeds were monitored until the proper developmental stage was reached (grasses 2-6" high). Blueberry, broadleaf weeds and grass covers were assessed pre-treatment and approximately one and two weeks post-treatments using a Daubenmire Cover Class scale, which was converted to percents. Blueberry and weed phytotoxicity were evaluated approximately one and two weeks after each treatment. Blueberry cover was slightly higher in the treated plots compared to the check plots both pre-treatment and for all four evaluations, but there were no significant differences. Broadleaf weed cover in the treated plots was significantly lower compared to the check plots by the second evaluation; it rebounded following the second (July) treatment, but was only about half the amount of cover in the check plots at the fourth evaluation. Grass cover was significantly suppressed in the treated plots at the second and third evaluations, but rebounded to a level equal to the check plots by the fourth evaluation The second treatment suppressed broadleaf weeds significantly compared to the check plots, which helped to allow blueberry cover to increase by 25%. However, late-emerging broadleaf weeds and regrowth of certain species such as dewberry should be taken into account when deciding when to apply a second treatment. The second treatment also increased grass control efficacy, but the timing of the second treatment may need to be refined to account for secondary flushes of grass growth. In this trial the Wyman's site was consistently behind the BBHF site in weed emergence and maturation, possibly because the Wyman's site was on an east-facing slope close to treelines to the east and south, while the BBHF site was open. By monitoring fields and applying the second treatment once new grass growth is 2-6 inches and late-season broadleaf weeds have emerged control could be improved PARTICIPANTS: David Yarborough was project leader, Jennifer D'Appollonio, provided technical support TARGET AUDIENCES: Target audience was the 600 wild blueberry growers in Maine. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
This combination treatment allows for a postemergence application thereby targeting the weeds as a spot treatment and combining both broadleaf and grass control with a single application. This will result in less herbicide use and a reduction in application cost.
Publications
- Yarborough, D. and DAppollonio. 2008. Mesotrione and hexazinone combinations for weed control in wild blueberries. Proceedings of the Northeastern Weed Science Society .62:12-13.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Tribenuron methyl was applied to a non-cropping wild blueberry field containing bunchberry in the fall of 2006 and 2007 to evaluate the herbicide's effectiveness in controlling bunchberry and potential injury to wild blueberry. Tribenuron methyl was applied at a rate of 0.43 oz ai a with a nonionic surfactant at 0.25 percent v/v to ten 1-m square plots per treatment date on 29 August, 26 September and 17 October 2006, and to a 24 by 50 ft block for each treatment date on 4 September, 17 September, and 3 October 2007. Ten 1-m square plots per treatment timing were evaluated at four weeks or two weeks post-treatment, respectively, for blueberry and bunchberry percent cover using a Daubenmire cover scale converted to percent cover, and results were compared to untreated control plots. In 2006 only, in ten 0.9-m square plots per treatment the blueberry and bunchberry stems were counted prior to all treatments and then recounted on 16 July 2007. On 16 July 2007 and 7 August 2008, percent blueberry and bunchberry covers were evaluated for all plots. The1-m square plots were hand-harvested on 2 August 2007 and 7 August 2008, respectively, and converted to pounds per acre. Percent cover data were analyzed using Duncan's Multiple Range test for the 2006 to 2007 data and paired t-tests for the 2007 to 2008 data; yields were analyzed using Duncan's Multiple Range test. In 2007 the 2006 August treatment had the highest blueberry cover and the lowest bunchberry cover. Blueberry cover was significantly higher in the August treatment than the other treatments, while bunchberry cover was significantly lower than the untreated control in the August and September treatments but not for the October treatment. The same trends held true for the stem counts, except that the blueberry stem count for the August treatment was significantly greater than the October treatment only. The October treatment had the highest yield, with the August treatment a close second, but the yields did not vary significantly among treatments in 2007. In 2008 the blueberry cover was significantly higher on the 4 September 2007 treatment than the previous year; the untreated and the September and October treatments were not significantly different. In 2008 the bunchberry cover was significantly lower on the check and all treatments. The untreated changed from 55 to 45 percent cover, but all of the treatments had significantly greater reductions in bunchberry cover with the 4 September treatment reduced from 75 to 5percent, the 17 September treatment from 63percent to 15 percent and the 3 October treatment from 20 to 5 percent. In all treatments blueberry yields were suppressed, but only the 17 September treatment was significantly lower than the untreated control. Tribenuron methyl is effective in reducing bunchberry cover without significantly reducing blueberry cover but still has the potential for reducing yields the year after application. PARTICIPANTS: David Yarborough was project leader, Jennifer D'Appollonio, provided technical support as did the Blueberry Hill Farm technician John Gaddis TARGET AUDIENCES: Target audience was the 600 wild blueberry growers in Maine. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
A State of Maine 24 C label for the Express TotalSol formulation was given in September 2008 for application in the crop year after harvest. This herbicide will provide a means of control for bunchberry which has consistently been listed as a major weed problem by wild blueberry growers for years. It also improves the competitiveness of Maine growers as this treatment has been available to Canadian wild blueberry growers for years.
Publications
- Yarborough, D.E. and J.L. D'Appollonio. 2009. FALL APPLICATION OF TRIBENURON METHYL FOR BUNCHBERRY CONTROL IN WILD BLUEBERRIES. Proceedings of the Northeastern Weed Science Society, V63. In press
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