Progress 10/01/10 to 09/30/15
Outputs
Target Audience:Target audiences of the information generated by this research include peer researchers at other institutions, cooperative extension professionals working with nursery and landscape professionals, and the nursery and landscape professionals themselves. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This project provided leveraging to aquire additional funds to support a graduate student working on biologically based weed management options. The graduate student received mentoring and training in research methods and weed management systems. The PI has presented the results at professional meetings. Participation in these meetings provided the opportunity to interact and learn from peers at other institutions. Research on biological control of weeds required collaborations with scientists in other disciplines. These collaborations provided enhanced understanding of pathogen systems and environmental interactions with biological control agents. Furthermore, the results of these experiments were incorporated into cooperative extension agent and grower workshops and training programs. Specifically, a series of workshops was conducted in NC, TN and FL to traing growers and cooperative extension agents on the principles of weed idenfication and weed management decision models. These workshops were conducted in concert with the the Southern Nursery IPM Working Group. How have the results been disseminated to communities of interest?Research results were shared with peers through presentations at professional meetings and publication of the results in peer reviewed journals and conference proceedings. Data were shared with the USDA IR-4 program to include in product registration data summaries. Additionally, research results were shared with product manufacturers and resulting in appropriate changes to product labels. Results were also incorporated into updated Extension guidelines housed on the PI's web site: http://www4.ncsu.edu/~jcneal/ What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Objective 1: Expand knowledge of preemergence and postemergence herbicide efficacy, Research conducted in this project has clarified the following Herbicide efficacy on weeds of increasing importance. Results from this research have resulted in improved guidelines for weed management in nursery crops and landscape plantings. Specifically, efficacy of nursery herbicides on livid amaranth (Amaranthus blitum, syn. A. lividus and also referred to as prostrate pigweed) was determined (Harlow and Neal 2013). Research during this project also contributed to the registration of indaziflam for use in landscape plantings and nursery crops. In comparison to other labeled herbicides, indaziflam was shown to have greater efficacy on Eclipta prostrata, a common summer annual weed in container nursery crops. Objective 2: Preemergence herbicide safety to ornamental crops was investigated. Key findings of this research include: All preemergence herbicides labeled for use in container nurseries have caused some injury to Hydrangea macrophylla. Our research demonstrated several strategies to reduce or mitigate that crop injury including product selection for minimizing injury potential, physical removal of granular herbicides from the growing points to avoid tip dieback, and irrigation interval management to reduce crop injury from spray-applied herbicides (Neal and Harlow 2015). Ornamental grasses continue to gain popularity in landscape plantings and "natural area" restoration projects. Yet, few herbicides are labeled for use on these species in production. The research conducted herein identified several herbicides which should NOT be used on ornamental grasses in production - including indaziflam and dimethenamid-p which caused significant injury to several popular species. Results from these studies were utilized by the manufacturers in label revisions warning growers to avoid such treatments. Similarly, our research demonstrated that, despite common beliefs, auxinic herbicides labeled for broadleaf weed control in turfgrasses were not safe when applied to ornamental grasses in production (Neal et al 2015). Preemergence herbicides were evaluated for safety to ornamental grasses in production. This work was part of a national coordinated trial which demonstrated the safety of isoxaben and pendimethalin on several species (Senesac et al. 2015). The data from these experiments will be incorporated into herbicide label revisions in the next 24 months. One trend in herbaceous perennial plant production has been to pot small transplants (288 tray plugs) directly into 3-liter pots for outdoor container production. Previously, these small transplants would be transplanted and established in larger cell-trays (72-cell or larger) before potting to outdoor production. Our research demonstrated that 72-cell tray transplants were not injured by labeled preemergence herbicides but 288-cell tray transplants were severely injured. Growers adopting the practice of directly planting 288 plugs to outdoor containers must avoid preemegence herbicide applications. (Harlow and Neal 2013) Objective 3: Evaluating biologically based weed management strategies. Research was conducted to evaluate the efficacy and safety of the biological control agent, Phoma macrostoma, for broadleaf weed control in turf and ornamental plantings. Additionally the biopesticides, MBI-005 and Fe-HEDTA were evaluated for broadleaf weed control in turf and container grown nursery crops. Phoma macrostoma controlled several important broadleaf weeds under greenhouse conditions but provided a limited spectrum of control under field conditions (Neal et al 2013). MBI-005 provided preemergence control of annual grass weeds (Wolfe et al. 2015), plus preemergence and postemergence control of many seedling broadleaf weeds (Neal et al 2013). Fe-HEDTA is labeled for broadleaf weed control in turfgrass, yet guidelines for use were ambiguous. Our research demonstrated that Fe-HEDTA dose had a much greater impact on weed control than did carrier volume or spray concentrations (Neal and Harlow 2014). The product label has since been revised to reflect these data.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Neal, J. C., J. C. Wolfe and C. Harlow. 2015. Auxinic herbicide phytotoxicity to container-grown Muhlenbergia capillaris and Miscanthus sinensis. J. Environ. Hort. 33(1):16
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2016
Citation:
Wolfe, J.C., J.C. Neal, and C. Harlow. 2016. Selective broadleaf weed control in turf with the bioherbicides Phoma macrostoma and Thaxtomin A Weed Technology (in press)
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Neal, J. C. and C. D. Harlow. 2015. Safety of pre-mixtures of glyphosate plus residual herbicides to landscape plants. Proc. Northeastern Weed Sci. Soc. 69:33
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Senesac, A, J.C. Neal, and J.F. Derr. 2015. Evaluation of preemergence herbicides for several container grown ornamental grasses. Proc. Northeastern Weed Sci. Soc. 69:38
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Neal, J.C and C. D. Harlow. 2015. Strategies for reducing preemergence herbicide injury to bigleaf hydrangea. Proc. Northeastern Weed Sci. Soc. 69:99
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Wolfe, J. C., J. C. Neal, and C. D. Harlow. 2015. Control of annual grasses in turf using the bioherbicide thaxtomin-A (MBI-005). Proc. Northeast. Weed Sci. Soc. 69:42
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Wolfe, J. C., J. C. Neal, and C. D. Harlow. 2015. Impact of application parameters on the efficacy of the bioherbicide FeHEDTA. Proc. Weed Sci. Soc. Amer. http://wssaabstracts.com/public/30/abstract-252.htm
|
Progress 10/01/13 to 09/30/14
Outputs
Target Audience: Three target audiences were reached -- scientific, outreach educators, and professional weed management personnel. Research progress was reported too peers at scientific meetings and in scientific literature. Research results were incorporated into web-based diagnostic resources and into educational workshops for Cooperative Extension professionals. Outcomes of this research were also communicated to commercial nursery crop producers and landscape maintenance professionals at cooperative extension and industry sponsored educational events. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? A graduate student was trained in reserach methodologies, data analysis, and reporting. Results from herbicide injury and efficacy evaluations were presented at field day training sessions for Cooperative Extension educators. How have the results been disseminated to communities of interest? Results have been presented at scientific meetings. A manuscript on ornamental grass tolerance to herbicides has been accepted for publcation in a refereed journal. Results from the hydrangea experiments have been submitted for publication in a trade magazine. Updated herbicide efficacy information has been incorporated into on-line decision aids available on the PI's web site: http://www4.ncsu.edu/~jcneal/ What do you plan to do during the next reporting period to accomplish the goals? The effiacy of spray and granular herbicide formulations on common nursery weeds, and the safety of these treatments will be compared. The relative cost-efficiency of different nursery weed management strategies will be compared. Biologically-based products will be tested for efficacy. Producted included in the next phase of testing include MBI010 and mevalocidin. Experiments to confirm dose and frequency of applications required to achieve commercially accpetable levels of weed control with bio-based products will continue. Results will be published in refereed journals and trade-oriented newsletters.
Impacts
What was accomplished under these goals?
Objective 1. Research was conducted to evaluate the efficacy of herbicides on several weed species of increasing imporance in nursery crops and landscape plantings. Results demonstrated that marsh parsley (Cyclospermum leptophyllum ) was controlled by only one herbicide currently labeled for use in these sites, dimethenamid-p. In contrast, petty spurge (Euphorbia peplus) was controlled by flumioxazin but not by dimethenamid-p. Objective 2. Preemergence herbicide safety to container grown ornamental grasses and hydrangea were investigated. Ornamental grasses were found to be generally tolerant of pendimethalin and isoxaben, but at high doses dithiopyr reduced rooting of plant tillers. Hydrangea paniculata plants were injured by most herbicides tested. Strategies to mitigate the damage were compared including physical removal of granular herbicides from foliage, irrigation immediately after planting, pruning to remove damaged foliage, and spray applied treatments. Data demonstrated that growers can avoid injury by avoiding HRAC Group E mode of action herbicides and physically removing granules from the foliage before irrigation. Objective 3. Evaluations of thaxtomin-A demonstrated residual control of Digitaria ischaemum and Poa annual similar to that provided by pendimethalin, an industry standard preemergence herbicide. Fe-HEDTA was evaluated for broadleaf weed control. These experiments demonstrated effective control was dose-related, with greater than at least 48 L/ha and multiple applications required for commercially acceptable control of winter annual broadleaf weeds. Perennial weeds were suppressed by these treatments but would require additional applications to achieve complete control. Phoma macrostoma controlled Dicondra caroliniana but did not provide acceptable levels of control for other species tested.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Neal, J. C. and C. Harlow. 2014. Spray volume and concentration effects on broadleaf weed control with Fe-HEDTA. Proc. Northeastern Weed Sci. Soc. 68:32
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Neal, J. C. 2014. History and progress toward developing biological control strategies for turfgrass systems. Proc. Weed Sci. Amer.
|
Progress 10/01/12 to 09/30/13
Outputs
Target Audience: Ultimately, the target audiences for this research are nursery crop producers and landscape weed management professionals. Additional target audiences are other Extension educators who utilize this information to aid clients in developing more effective weed management practices. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? Research progress has been reported at appropriate scientific conferences. Results from the research have also be incorporated into Cooperative Extension educational programs, Cooperative Extension agent training events, and Cooperative Extension resources. What do you plan to do during the next reporting period to accomplish the goals? Research will continue to evaluate the efficacy of natural products for weed control in landscapes and nursery crops. Specific objectives for the next reporting period will be to refiine preemergence application strategies for crabgrass and annual bluegrass control with Thaxtomin-A; safety to established and newly seeded turfgrasses; application intervals and doses for Fe-HEDTA; safety of bio-based treatments on dormant and semi-dormant ornamental plants. Additional research to refine our understanding of preemergence herbicide safety to ornamental grasses and hydrangea macrophylla are planned.
Impacts
What was accomplished under these goals?
Investigations were conducted to evaluate the efficacy and safety of preemergence and postemergence herbicides for container nurseries and landscapes. Research during this reporting period emphasized improved longevity of residual weed control in container nursery crops and development of bio-based and natural products for weed control. Research was conducted on the crop safety and residual longevity of indaziflam in container nursery crops. Research continued with bioherbicides including thaxtomin-A and Phoma macrostoma and Fe-HEDTA for selective broadleaf weed control. These bioherbicides provided preemergence and postemergence control of many annual and perennial broadleaf weeds. Fall applications of these products provided weed control comparable to industry standard herbicides, but the spectrum of weeds controlled is narrower than with traditional herbicides. Fe-HEDTA provided effective control of many dicot weeds in turfgrass. Based on this research application instructions should be modified to define application dosage on an area basis rather than dilution-based. Thaxtomin-A was evaluated for preemergence control of annual grass and broadleaf weeds. Results suggest that residual crabgrass control comparable to industry standard herbicides may be possible with sequential applications.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Harlow, C. and J. Neal. 2013. Effects of time after transplanting on herbicide safety to Heuchera. Proc. Northeastern Weed Sci. Soc. 67:24
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Neal, J. C. and C. Harlow. 2013. Prostrate pigweed control in containers. Proc. Southern Nursery Assoc. Res. Conf. 58:336-338
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Neal, J. C., R. Schiavone, and C. Harlow. 2013. Seedling broadleaf weed control with MBI-005. Proc. Northeastern Weed Sci. Soc. 67:98
- Type:
Conference Papers and Presentations
Status:
Awaiting Publication
Year Published:
2014
Citation:
Neal, J. C., B. Shew, and R. Schiavone. 2013. Temperature and dose influence Phoma macrostoma efficacy on seedling broadleaf weeds. Proc. International Bioherbicide Group Workshop. (in press)
|
Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Investigations were conducted to evaluate the efficacy and safety of preemergence and postemergence herbicides for container nurseries and landscapes. Spray-applied herbicides can be more economical but have greater likelihood of crop injury compared to granular formulations. Research was conducted to determine if spray application-to-irrigation intervals could be managed to reduce crop injury. Contrary to reports from other researchers, our data demonstrated that crop injury from spray applications of preemergence herbicides is not mitigated by irrigation shortly before and after herbicide application. Phenoxy herbicides are used for broadleaf weed control in many grass crops but in our research these herbicides injured ornamental grasses in production. Research continued with bioherbicides, thaxtomin and Phoma macrostoma, for selective broadleaf weed control. These bioherbicides provided preemergence and postemergence control of many annual and perennial broadleaf weeds. Fall applications of these products provided weed control comparable to industry standard herbicides, but the spectrum of weeds controlled is narrower than with traditional herbicides. In particular, common chickweed is not controlled by either bioherbicide. PARTICIPANTS: J.C. Neal, Principal Investigator; Chris Harlow, Research Technician; The PI and research technicians designed and conducted all experiments. Collaborations were established with Dr. Karen Bailey of Agriculture Canada, Dr. Stuart Faulk of The Scotts Co., and Dr. Tim Johnson of Marrone Bio Innovations to evaluate products for biologically based weed management. TARGET AUDIENCES: Ultimately, the target audiences for this research are nursery crop producers and landscape weed management professionals. Additional target audiences are other Extension educators who utilize this information to aid clients in developing more effective weed management practices. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Label expansion for preemergence herbicides has led to improved weed control in container and field nurseries. Research on spray-applied herbicides will help growers avoid crop injury. Growers wishing to utilize spray-applied herbicides in container nurseries need to carefully select herbicides for crop safety. Also, growers of ornamental grasses must avoid the use of phenoxy herbicides in production settings.
Publications
- Harlow, C. and J. C. Neal. 2012. Phenoxy herbicide safety in container production of Muhlenbergia and Miscanthus. Proc. Northeastern Weed Sci. Soc. 66:66.
- Neal, J. C., C. Harlow, and B. Fair. 2012. Safety and efficacy of mulch and mulch/herbicide combinations in pansy beds. Proc. Northeastern Weed Sci. Soc. 66:66.
|
Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: Investigations were conducted to evaluate the efficacy and safety of preemergence herbicides for container nurseries and landscapes. In this research indaziflam, a new mode of action class of chemistry for weed management in nursery crops, provided greater longevity of residual weed control compared to labeled products. Safety of liquid and granular formulations of dimethenamid-p to ornamentals continued. Research from the past 5 years of this project was instrumental in registration of the granular combination of dimethenamid-p plus pendimethalin, trade name "Freehand", for preemergence weed control in ornamental plant production and maintenance. Biologically-based alternatives for weed control in landscape settings were evaluated. Preliminary experiments with MBI-005 (thaxtomin) and Phoma macrostoma identified limitations in weed control spectra which will be addressed in future research. PARTICIPANTS: J.C. Neal, Principal Investigator; Chris Harlow, Research Technician; Rocco Schiavone, Research Technician. The PI and research technicians designed and conducted all experiments. Collaborations were established with Dr. Karen Bailey of Agriculture Canada, Dr. Stuart Faulk of The Scotts Co., and Dr. Tim Johnson of Marrone Bio Innovations to evaluate products for biologically based weed management. TARGET AUDIENCES: Ultimately, the target audiences for this research are nursery crop producers and landscape weed management professionals. Additional target audiences are other Extension educators who utilize this information to aid clients in developing more effective weed management practices. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Label expansion for preemergence herbicides has lead to improved weed control in container and field nurseries. Research on dimethenamid-p experiments will avoid crop injury by resulting in label guidelines and precautions that restrict treatments on species and under conditions that have been shown to cause crop injury.
Publications
- Post, A. R., R. Ali, A. Krings, Jenny Xiang, B. R. Sosinski and J. C. Neal. 2011. On the identity of the weedy bittercresses (Cardamine : Brassicaceae) in United States nurseries: evidence from molecules and morphology. WeedScience 59:123-135.
- Little, D. and J. Neal. 2010. Tower (dimethenamid-p) safety and efficacy in nursery crops. Proc. Northeastern Weed Sci. Soc. 64:100.
- Neal, J. and K. Rorem. 2010. Indaziflam and Oxadiazon combinations for weed control in containers. Proc. Northeastern Weed Sci. Soc. 64:101.
|
Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Investigations into the efficacy and safety of dimethenamid-p herbicides on demonstrated efficacy on several important weeds of container nurseries and landscapes. Research from the past 5 years of this project was instrumental in registration of the granular combination of dimethenamid-p plus pendimethalin, trade name "Freehand", for preemergence weed control in ornamental plant production and maintenance. Invasive plants are negatively impacting natural areas and urban landscapes. An invasiveness assessment protocol was developed. This protocol has been adopted by the NC Nursery and Landscape association and stimulated discussions with land conservancy advocacy groups. PARTICIPANTS: PARTICIPANTS: J.C. Neal and T. Ranney, principal investigators, and C. Trueblood, graduate research assistant; Chris Harlow, Research Technician; Katie Pound, undergraduate intern. Partner Organization: North Carolina Nursery and Landscape Association partially funded the research on invasive plant species. TARGET AUDIENCES: Ultimately, the target audiences for this research are nursery crop producers and landscape weed management professionals. Additional target audiences are other Extension educators who utilize this information to aid clients in developing more effective weed management practices. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Recent research progress has contributed to the registration of dimethenamid-p for nursery and landscape uses. Adoption of this new technology has improved weed management, thereby reducing hand weeding costs for nursery and landscape professionals. Additionally, research has resulted in dialogue between the nursery industry and land conservancy advocates to assess invasive plants currently in the nursery trade.
Publications
- Post, A.R., J. C. Neal, A. Krings, B. R. Sosinski, and Q. Xiang. 2009. New Zealand bittercress (Cardamine corymbosa; Brassicaceae): new to the United States. Weed Technol. 23:604-607.
- Trueblood, C. E., T. G. Ranney, N. P. Lynch, J. C. Neal, and R. T. Olson. 2010. Evaluating Fertility of Triploid Clones of Hypericum androsaemum L. for use as Non-invasive Landscape Plants. HortScience 45(7):1026-1028.
- Walker, L.H., J.C. Neal, and J.Derr. 2010. Preemergence control of doveweed (Murdannia nudiflora) in container grown nursery crops. J. Environ. Hort. 28(1):8-12.
|
Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: An invasive plant assessment protocol was developed to aid nursery crop producers in evaluating species / varieties currently in production which may have invasive characteristics. This protocol has been presented to the NC Nursery and Landscape Association invasive plant committee and the NC Exotic Pest Plant Council for comments. Investigations into the safety of dimethenamid-p herbicides on herbaceous ornamental plants demonstrated good plant safety on several species but injury to others. This research highlighted the importance of thoroughly understanding crop safety research on this new herbicide prior to label expansion. PARTICIPANTS: J.C. Neal, Principal Investigator; Clara Englert Trueblood, Graduate Research Assistant; Lela Walker, Graduate Research Assistant; Daniel Little, Research Associate; Laura Howe, undergraduate intern. Ms. Howe participated in an undergraduate independent study evaluating the safety of dimethenamid-p and other herbicides on landscape plantings of herbaceous ornamentals. TARGET AUDIENCES: Ultimately, the target audiences for this research are nursery crop producers and landscape weed management professionals. Additional target audiences are other Extension educators who utilize this information to aid clients in developing more effective weed management practices. PROJECT MODIFICATIONS: Growers in the region have starting adopting the use of dimethenamid-p herbicide for yellow nutsedge and summer annual weed control. Cautious adoption of this technology has resulting in very few adverse impacts on crops in the first two seasons of technology adoption.
Impacts
Our research demonstrated that the dominant species of bittercress (Cardamine) has been commonly mis-identified because most North American keys to the genus did not contain the introduced species, Cardamine flexuosa. This new identification has been reported to researchers and educators working in the field of nursery weed management, and included in the publication -- Weeds of Container Nurseries. Research from this project had a significant impact on the 2008 labeling of dimethenamid-p for weed control in nursery crops and landscape plantings. However, our research also demonstrated that growers should use caution in adopting this new technology as certain species have been shown to be injured under some conditions. Results of our research were incorporated into the product label instructions and precautions, reported to grower meetings in NC, and shared with other educators in the field.
Publications
- LeBude, A., B. L. Upchurch, and J. C. Neal. 2009. Preemergence Herbicide Applications to Six Containerized Woody Ornamental Rootstocks do not Affect Winter Grafting Success. J. Environ. Hort. 27(2):119-122.
- Post, A. R., A. Krings, Qui-Yun Xiang, B. R. Sosinski, and J. C. Neal. 2009. Lectotypification of Cardamine flexuosa (Brassicaceae). J. Bot. Res. Inst. Texas (formerly SIDA) 3(1):227-230.
- Post, A. R., A. Krings, W. Wall, and J. C. Neal. 2009. Introduced lesser celandine (Ranunculus ficaria, Ranunculaceae) and its putative subspecies in the United States: a morphometric analysis. J. Bot. Res. Inst. Texas (formerly SIDA) 3(1):193-209.
- Englert, C.A. and J. C. Neal. 2009. Preemergence herbicide efficacy on four species of spurge. Proc. Northeastern Weed Sci. Soc. 63:32.
- Little, D.A, J.C. Neal and A.R. Post. 2009. Efficacy of various cut stump herbicide applications on wisteria, privet and paulownia. Proc. Northeastern Weed Sci. Soc. 63:3.
- Neal, J.C. 2009. Efficacy and safety of dimethenamid-p + pendimethalin in container nursery crops. Proc. Northeastern Weed Sci. Soc. 63:65.
- O'Driscoll, M.G., J.C. Neal, D.A. Little, and T.H.Shear. 2009. Postemergence control of common periwinkle in a forested urban park. Proc. Northeastern Weed Sci. Soc. 63:12.
- Post, A.R. and J.C. Neal. 2009. Herbicide efficacy comparisons on bittercress accessions from container nurseries. Proc. Northeastern Weed Sci. Soc. 63:37.
- Walker, L.C. and J.C. Neal. 2009. Nonselective postemergence control of spurge and bittercress in containers. Proc. Northeastern Weed Sci. Soc. 63:34.
- Walker, L.C., J.C. Neal and L.P. Tredway. 2009. Screening fungal pathogens of Microstegium vimineum as potential biocontrol agents. Proc. IXth International Bioherbicide Group Workshop. 9:7-10.
|
Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: The most common cool-season weed in container nurseries is bittercress (Cardaminie spp.). Significant confusion exists regarding the correct identification of this species. Nurseries were surveyed and voucher specimens examined. Species were categorized using morphological and molecular data. This study identified three species of bittercress, one of which is a new record for North America. The most common bittercress species in nurseries is Cardamine flexuosa. Accessions of C. flexuosa were morphologically and genetically diverse. Plants varied in germination percentages, time to emergence, and seedling vigor after emergence. Based on preliminary data, susceptibility to common nursery herbicides appears to vary among accessions. Spurge (Chamaecyse spp = Euphorbia spp.) is the most common summer annual weed in nurseries. We have collected six species of Chamaecyse in container nurseries in NC. Variable responses to common herbicides labeled for spurge control was observed with C. hyssopifolia being more tolerant of herbicides than C. hirta, C. nutans, C. prostrata. Chamaecyse maculata, the most commmon species, displayed variable results from year to year -- perhaps as a result of different seed sources. PARTICIPANTS: J. C. Neal, Ph.D.: Principle investigator. Professor of weed science. Conducted training sessions at nursery grower meetings in NC, TX, OK, FL, and OR in which information from this research was the focus. A. R. Post: Master of Science graduate student. Completed degree requirements in August 2008. Currently a Ph.D. student at Cornell University. D. A. Little: Research Assistant, Department of Horticultural Science. Responsible for woody vegetation control studies including wet blade technology evaluations. R. Atwood: student intern (2007). Recipient of the BASF Corporation internship. Responsible for experiments comparing longevity of weed control and economics of Freehand use in container nurseries. I. Wong: student intern (2008). Recipient of the BASF Corporation internship. Responsible for experiments comparing the safety of Freehand on container grown herbaceous perennials. L. Walker: Master of Science graduate student. Conducting research on biological control of weeds. C. Englert: Master of Science graduate student. Research project involves developing an invasiveness assessment protocol for potentially invasive species in North Carolina nurseries. Also comparing Chamaecyse species control in containers. TARGET AUDIENCES: Cooperative Extension faculty, container nursery managers and landscape managers. PROJECT MODIFICATIONS: Research with two biological control agents (Phoma macrostoma and Chondrosterium purpureum) yielded little to no weed control. Therefore, the emphasis of the project was shifted toward understanding the biology and management of nursery and landscape weeds (other objectives included in the project proposal). No project revision was deemed necessary as the research on these organisms was conducted as described in the proposal, with negative results reported.
Impacts
We have identified several new species of weeds moving in nurseries and effective control measures for these species. The results of these tests have been reported at scientific meetings, grower meetings, and incorporated into updated Extension guidelines for nursery weed control. Additionally, research conducted in prior years of this project have contributed to significant label expansions for herbicides in nurseries and landscapes, and have been instrumental in the registration of a new herbicide (Freehand) for nutsedge and summer annual weed control in container nurseries and landscapes. This is the first granular herbicide registered for use in landscape ornamentals for the control of many tough weeds including nutsedge, doveweed, phyllanthus, and eclipta.
Publications
- Little, D.A., Post, A.R., and Neal, J.C. 2008. Efficacy of hand-held wet blade herbicide applications on sweet gum, maple and tulip poplar. Proc Northeastern Weed Sci. Soc. 62:10.
- Neal, J.C. 2008. Efficacy of dimethenamid-P and pendimethalin granular combinations. Proc. Northeastern Weed Sci. Soc. 62:50.
- Post, A., Krings, A., Xiang, J., Sosinski, B., and Neal, J. 2008. Taxonomy and Phylogeny of Weedy Cardamine Species in United States Nurseries. Proc. Weed Sci. Soc. Amer. http://wssa.net/Meetings/WSSAAbstracts/abstractsearch.php (accessed Nov 2008)
- Post, A.R., Neal, J.C., Krings, A., Sosinski, B.R., and Xiang, Q. 2008. Cardamine weed species in United States Nurseries. Proc. Northeastern Weed Sci. Soc. 62:27.
- Judge, C.A., Neal, J.C., and Shear, T.H. 2008. Japanese stiltgrass (Microstegium vimineum) management for restoration of native plant communities. Invasive Plant Science and Management 1:111-119.
- Atwood, R.P.M., Walker, L.C., and Neal, J.C. 2008. Longevity of weed control in containers with BAS659H. Proc. Northeastern Weed Sci. Soc. 62:26.
- Derr, J.F. and Neal, J.C. 2008. Preemergence control of doveweed in nursery crops. Proc. Northeastern Weed Sci. Soc. 62:80.
- Little, D.A. and Neal, J.C. 2008. Showcase efficacy and safety in container grown nursery crops. Proc. Northeastern Weed Sci. Soc. 62:83.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Trials were conducted to evaluate the efficacy of labeled herbicides on recently introduced weeds and weeds of increasing importance in nursery and landscape settings -- including doveweed, nodding spurge, hyssop spurge, prostrate spurge, petty spurge, marsh parsley, and Asiatic hawksbeard. These data have documented differential sensitivity of these introduced weeds to commonly used herbicides. In particular, no currently labeled herbicide provided adequate control of marsh parsley. Additionally, the four species of spurge displayed differential sensitivity to common preemergence herbicides. The results from these trials will be reported in applied journal articles and extension publications in 2008. Research on dimethenamid-p had demonstrated safety to a wide variety of woody and herbaceous ornamentals as well as efficacy on a wide range of difficult to control weeds including doveweed, phyllanthus, eclipta, spurge, bittercress, yellow nutsedge and many other common
nursery and landscape weeds. Continued research on a granular formulation has demonstrated greater crop safety. Chondrosterium purpureum is labeled in Canada for the suppression of woody weeds. Applications to common woody landscape weeds and invasive weed species in NC resulted in no control. Reasons for this negative data are unclear.
PARTICIPANTS: Joseph C Neal. Lead investigator and responsible for supervising all aspects of these projects. Dr. Jeffrey Derr, Virginia Tech -- cooperator on collaborative evaluation of herbicide efficay on "new" weeds. Ms. Angela Post, M.S. student, conducted evaluations of a biological control agent for woody weeds and is investigating the taxonomy and management of Cardamine spp. (one of the most common weeds of nurseries)
TARGET AUDIENCES: Target audiences include Cooperative Extension staff in NC and at other Universities, nursery crop producers, landscape maintenance professionals, and sales representatives. Results were shared with other extension professionals at scientific meetings including the Northeastern Weed Science Society annual conference. Cooperative extension agents received updates at field days utilizing demonstrations of product performance. Formal presentations were made to grower groups in NC, OK, and TX that included results from these trials. Chemical company sales representatives received training in NC and CA.
Impacts
Results from these trials have been incorporated into Extension publications and presentations to grower groups enabling practitioners to make more informed weed management decisions. Results from these research trials have also supported the registration of dimethenamid-p for preemergence weed control in nursery and landscape plantings. This registration will provide growers and landscapers with a more effective options for preemergence control of yellow nutsedge, doveweed and other hard to control species.
Publications
- Derr, J. and J. C. Neal. 2007. Control of new weed species in the nursery industry. Proc. Northeastern. Weed Sci. Soc. 61:32.
- Judge,C. A. and J. C. Neal. 2006. Early postemergence control of nursery weeds with Broadstar, OH2 and Snapshot TG. J. Environ. Hort 24(2):105-108
- Hundley, D. and J. C. Neal. 2007. Ground cover suppression in North Carolina Fraser fir production. Proc. Northeastern. Weed Sci. Soc. 61:39.
- Neal, J. C. 2007. Get Weeds Out of Your Pots. Nursery Management and Production. July 2007. page 30-36.
- Neal, J. C., J. F. Derr, and A. F. Senesac. 2007. Safety of postemergence nutsedge-control herbicides on ornamentals. Proc. Northeastern. Weed Sci. Soc. 61:35.
- Post, A. R., J. C. Neal, and C. A. Judge. 2007. Herbicide comparison in wet blade applications for sweet gum, tulip poplar and red maple control. Proc. Northeastern. Weed Sci. Soc. 61:70
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Progress 10/01/05 to 09/30/06
Outputs
New weeds are introduced to the nursery industry and distributed rapidly in container crops. Research in 2006 has evaluated the efficacy of labeled herbicides for control of several recently introduced species including Rorippa islandica, Epilobium ciliatum, Galinsoga ciliata, Apium lepidiphylum, Murdannia nudiflora and Euphorbia peplus. Control varied among herbicides. Standard nursery herbicides container oxyfluorfen controlled rorippa, Apium and Euphorbia but did not control Epilobium, Galinsoga or Murdannia. Flumioxazin, recently labeled for nursery weed control provided excellent control of Murdannia but only fair control of Galinsoga. Dimethenamid controlled all weeds in this trial except rorippa and galinsoga. In separate trials, dimethenamid was found to be safe when applied over the top of many woody and herbaceous ornamentals. Future research will continue to evaluate the safety and efficacy of herbicides for controlling "new weeds" with particular emphasis
on dimethenamid. Certain amino acids have been shown to be selectively phytotoxic to some seedling weeds. Cardamine hirsuta is the most common cool season weed of nursery industries and one of the most expensive to hand weed. A preliminary screening study suggests that tryptophan is phytotoxic to Cardamine hirsuta seedlings. Further research will attempt to confirm this preliminary observation.
Impacts
Despite the availability of several herbicides for use in nursery crops and landscape plantings, several weeds continue to escape control. New herbicides with safety to woody and herbaceous ornamental plants, and efficacy on tough to control weeds are in development and show promise to enhance nursery and landscape weed control in the near future.
Publications
- Judge, C. A., J. C. Neal. and J.F. Derr. 2005. Preemergence and postemergence control of Japanese stiltgrass (Microstegium vimineum). Weed Technol. 19:183-189
- Judge, C. A., J. C. Neal. and J.F. Derr. 2005. Response of Japanese Stiltgrass (Microstegium vimineum) to application timing, rate, and frequency of postemergence herbicides. Weed Technol. 19:912-917.
- Judge,C. A. and J. C. Neal. 2006. Early postemergence control of nursery weeds with Broadstar, OH2 and Snapshot TG. J. Environ. Hort 24(2):105-108
- Neal, J. C. 2006. A method for estimating PRE herbicide residual longevity in container nursery substrates. Proc. Weed Sci. Soc. Amer. 46:101.
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Progress 10/01/04 to 09/30/05
Outputs
Safety of newly labeled preemergence herbicides on container grown woody and herbaceous perennials was evaluated. Broadstar (flumioxazin) injured young seedling wax myrtles and Chinese privet liners. However, one-year old wax myrtles and privet plants were not injured. These data confirm that plant age impacts the safety of this herbicide. Managing weeds around nursery crop production areas is an essential component of nursery weed IPM programs. Standard treatments have not provided adequate control of some weeds including Murdannia nudiflora and Cyperus compressus. Treatments with flumioxazin 51DF (SureGuard) combined with glyphosate provided superior control of these and other common nursery weeds compared to a standard herbicide program.
Impacts
The use of flumioxazin (Sureguard 51DF) for weed control in non-crop areas in container nurseries should improve sanitation practices in container nurseries, reducing weed seed spread to crops. The guidelines for Broadstar use in established one-year old crops will reduce the likelihood of crop injury from this herbicide.
Publications
- No publications reported this period
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