Progress 09/01/14 to 08/31/18
Outputs
Target Audience:Agricultural Professionals Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Ms. Jess Bunchek was the graduate student conducting the research as part of her MS degree program. Each summer, four additional undergraduate students participated in the project. In addition to this, a number of presentations have been made to ag professionals across the region. How have the results been disseminated to communities of interest?We have actively disseminated information via professional and extension education channels as well as publishing in peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Cover Crop Windows Experiment (2015-2017). In Sept 2015 and 2016, we established field experiments at Penn State and the University of Delaware and collected data during the spring and summers of 2016 and 2017. This experiment addressed two primary objectives: 1) determine the mechanisms by which selected cover cropping strategies designed for no-till systems affect weed population dynamics, 2) determine the effects of winter cover crop strategies on herbicide resistance selection pressure. Cover cropping treatments are being evaluated following small grain production and are imposed as a RCBD with a split-plot and four replications. Main plots are cover cropping strategies. Seven cover cropping treatments are established in early September to simulate longer fall growing windows following small grains: cereal rye (134 kg/ha), spring oats (134 kg/ha), cereal rye + hairy vetch (34 + 34 kg/ha), cereal rye + crimson clover (34 + 22 kg/ha), cereal rye + forage radish (101 + 6 kg/ha), spring oats + hairy vetch (34 + 34 kg/ha), and a no cover crop control. Three cover treatments were also planted in early October to simulate a shorter fall growing window following summer annual cash crops. These treatments include cereal rye (134 kg/ha), cereal rye + hairy vetch (34 + 34 kg/ha), and cereal rye + crimson clover (34 + 22 kg/ha). Split plots include cover crop termination timing, where the first termination date aligns with cereal rye boot stage, and the second termination date aligns with either cereal rye heading stage or when hairy vetch turns reproductive. Weed microplots were established in each split plot for both horseweed and smooth pigweed. Smooth pigweed establishment was less successful than horseweed. Data collection methods described in 'Strategies' has been used for horseweed. Data Collection. Cover Crop Strategies Experiment. Cover crop ground cover visually estimated by species in weed microplots 5 and 10 weeks after planting (WAP). Cover crop biomass (kg ha-1) was collected by species 10 WAP and at spring burndown. Horseweed density and size was quantified at 10 WAP, at spring-burndown and 4 weeks after spring-burndown treatments (WAT). This methodology was also used for smooth pigweed microplots. Additional datasets collected include: 1) summer annual weed biomass by species 4 WAT, 2) horseweed density prior to soybean harvest, and 3) cover crop nitrogen content and C:N ratios at burndown. Results. Interannual variation in growing conditions (study year) and intra-annual variation in soil fertility (low vs. high nitrogen) were the primary drivers of cover crop response traits and significantly affected horseweed density at the time of herbicide exposure. In comparison to the fallow control, cover crop treatments reduced horseweed density 52% to 86% at the time of a preplant, burndown application. Cereal rye (Secale cereale L.) alone or in combination with forage radish (Raphanus sativus L.) provided the most consistent horseweed suppression. Fall and spring cover crop biomass production was negatively correlated with horseweed density at the preplant burndown application timing. Our results also show that winter-hardy cover crops reduce the size inequality of horseweed populations at the time of herbicide exposure by reducing the number of large individuals within the population. Finally, we advocate for advancement in our understanding of complementarity between cover crop- and herbicide-based management tactics in no-till systems to facilitate development of proactive, herbicide-resistant management strategies. This study resulted in the following peer-reviewed publication - Wallace J., W. Curran, and D. Mortensen. 2019. Cover crop effects on horseweed (Conyza canadensis) density and size inequality at the time of herbicide exposure. Weed Sci. 67: 327338. Cover Crop IWM Experiments (2015-2017). In Sept 2015 and 2016, we established the two field experiments at Penn State and University of Delaware and collected data during the spring and summers of 2016 and 2017. This set of experiments addresses two primary objectives: 1) determine the effects of winter cover crop strategies on herbicide resistance selection pressure, and 2) determine the ability of cover crops to suppress weeds while influencing other valued ecosystem services provided by the cover crops. At each site, one experiment evaluates cover crop treatments following small grains using an early-Sept planting date, which is terminated and planted to corn in the spring. The other experiment evaluates cover crops following corn-silage using an early-October planting date, which is terminated and planted to soybean in the spring. In both experiments cover cropping treatments are imposed as a RCBD with a split plot and four replications. Main plots are cover crop treatments. In the post small grains experiment, cover cropping treatments include: no cover control, cereal rye + hairy vetch (34 + 34 kg/ha), and cereal rye + crimson clover (34 + 22 kg/ha). In the post corn silage experiment, cover crop treatments include: no cover control, cereal rye (134 kg/ha) and cereal rye + hairy vetch (101 + 22 kg/ha). The split-plot treatment is the herbicide program. Herbicide programs include: 1) burndown application only, 2) burndown + pre-emergent residual application, 3) burndown + post-emergent application and 4) burndown + pre-emergent residual application + post-emergent application. Weed microplots are established using the methodology described in the 'Cover Crop Strategies Experiment' for both horseweed and smooth pigweed and data were collected as previously described. Results. The effect of alternative cover crops was evaluated across a range of herbicide inputs. Cover crop biomass production ranged from 2,000 to 8,500 kg/ha in corn and 3,000 to 5,500 kg/ha in soybean. Experimental results demonstrated that herbicide-based tactics were the primary drivers of total weed biomass production, with cover-cropping tactics providing an additive weed suppression benefit. Substitution of cover crops for PRE or POST herbicide programs did not reduce total weed control levels or cash crop yields but did result in lower net returns due to higher input costs. Cover-cropping tactics significantly reduced horseweed populations in three of four cover crop treatments and decreased the number of large rosettes (>7.6-cm diameter) at the time of preplant herbicide exposure. Substitution of cover crops for PRE herbicides resulted in increased selection pressure on POST herbicides but reduced the number of large individuals (>10 cm) at POST applications. Collectively, our findings suggest that cover crops can reduce the intensity of selection pressure on POST herbicides, but the magnitude of the effect varies based on weed life-history traits. Additional work is needed to describe proactive resistance management concepts and performance targets for integrating cover crops so producers can apply these concepts in site-specific, within-field management practices. This study resulted in the following peer-reviewed publication - Bunchek, J.M., J.M. Wallace, W.S. Curran, D.A. Mortensen, M.J. VanGessel, and B.A. Scott. 2020. Alternative performance targets for integrating cover crops as a proactive herbicide-resistance management tool. Weed Sci. 68: 534-544. DOI: 10.1017/wsc.2020.49.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2020
Citation:
Bunchek, J., Wallace, J., Curran, W., Mortensen, D., VanGessel, M., & Scott, B. 2020. Alternative performance targets for integrating cover crops as a proactive herbicide-resistance management tool. Weed Science, 68(5), 534-544. doi:10.1017/wsc.2020.49
- Type:
Journal Articles
Status:
Accepted
Year Published:
2019
Citation:
John M. Wallace, William S. Curran, David A. Mortensen. 2019. Cover Crop Effects on Horseweed (Erigeron canadensis) Density and Size Inequality at the Time of Herbicide Exposure," Weed Science, 67(3), 327-338.
|
Progress 09/01/16 to 08/31/17
Outputs
Target Audience: Our target audience is producers who practice conservation tillage in an intensively managed grain production system within the mid-atlantic. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Jess Bunchek is the graduate student conducting the research as part of her MS degree. In 2017, four additional undergraduate students participated in the project. How have the results been disseminated to communities of interest?yes, a number of presentations have been given at various venues. Conference presentations provided in a separate section. The following grower/producer/ag professional meeting also occurred: Curran, W.S. 2017. What's new for weed control: cover crops and winter annual weed management. Lancaster County Crops Day, Jan. 17. Curran, W.S. 2017. What's new for weed control: cover crops and winter annual weed management. Franklin County Crops Day, Jan. 24. Curran, W.S. 2017. What's new for weed control: cover crops and winter annual weed management. Union County Crops Day, Jan. 27. Curran, W.S. 2017. What's new for weed control: cover crops and winter annual weed management. Bedford County Crops Night, Jan. 30. Curran, W.S. 2017. What's new for weed control: cover crops and winter annual weed management. Frederick MD Crops Day, Feb. 17. Curran, W.S. 2017. What's new for weed control: cover crops and winter annual weed management. Susquehanna County Crops Day, Feb. 21. Curran, W.S. 2017. What's new for weed control: cover crops and winter annual weed management. Sommerset County Crops Eve., Mar. 2. Bunchek, J. 2017. Cover crops and weed management. Penn State Rock Springs Weed Tour, July 11. Curran, W. S. 2017. Integrated weed management and cover crops. USDA Area-Wide project field day, Nov. 2, 2017 Curran, W.S. 2017. Cover crops and weed management. Northeast Cover Crop Council Field Tour, Big Flats, NY, Nov. 9. Curran, W.S. 2017. Cover crops and weed management. Natl Conf. on Cover Crops and Soil Health, Indianapolis, IN, Dec. 7-8. Curran, W.S. 2017. Cover crops and weed management. Cumberland Valley Planter Clinic, Shippensburg, PA, Dec. 13. What do you plan to do during the next reporting period to accomplish the goals?We have completed the field work and will work on writing up the results for peer review and continue to developeducational materials.
Impacts
What was accomplished under these goals?
1) Continued Cover Crop Windows Experiment (2015-2017). In Sept 2016, we established the second year of field experiments at PSU-RELARC and UD-CREC. This experiment addresses two primary objectives: 1) determine the mechanisms by which selected cover cropping strategies designed for no-till systems affect weed population dynamics, 2) determine the effects of winter cover crop strategies on herbicide resistance selection pressure. Cover cropping treatments are being evaluated following small grain production and are imposed as a RCBD with a split-plot and four replications. Main plots are cover cropping strategies. Seven cover cropping treatments are established in early September to simulate longer fall growing windows following small grains: cereal rye (134 kg ha-1), spring oats (134 kg ha-1), cereal rye + hairy vetch (34 + 34 kg ha-1), cereal rye + crimson clover (34 + 22 kg ha-1), cereal rye + forage radish (101 + 6 kg ha-1), spring oats + hairy vetch (34 + 34 kg ha-1), and a no cover crop control. Three cover treatments were also planted in early October to simulate a shorter fall growing window following summer annual cash crops. These treatments include: cereal rye (134 kg ha-1), cereal rye + hairy vetch (34 + 34 kg ha-1), and cereal rye + crimson clover (34 + 22 kg ha-1). Split plots include cover crop termination timing, where the first termination date aligns with cereal rye boot stage, and the second termination date aligns with either cereal rye heading stage or when hairy vetch turns reproductive. Weed microplots were established in each split plot using the methodology described in the 'Cover Crop Strategies Experiment' for both horseweed and smooth pigweed. Data collection methods described in 'Strategies' has been used for horseweed. An overview of results shows that cover crops planted at the second date produce the same biomass and percent ground cover as similar treatments planted at the first date, so long as the cover crops are well-established. Further, the local populations of horseweed planted in the microplots tends to germinate more so in the spring, so cover cropping treatments that feature one or more winter-hardy cover crops suppress horseweed greater than cover cropping treatments that target fall-emerging weed cohorts. Finally, cover crops that produce greater summer residue, such as cereal rye, successfully physically suppress smooth pigweed. 2) Continued Cover Crop IWM Experiments (2015-2017). In Sept 2016, we established the second year of two field experiments at PSU-RELARC and UD-CREC. This set of experiments addresses two primary objectives: 1) determine the effects of winter cover crop strategies on herbicide resistance selection pressure, and 2) determine the ability of cover crops to suppress weeds while influencing other valued ecosystem services provided by the cover crops. At each site, one experiment evaluates cover crop treatments following small grains using an early-Sept planting date, which is terminated and planted to corn in the spring. The other experiment evaluates cover crops following corn-silage using an early-October planting date, which is terminated and planted to soybean in the spring. In both experiments cover cropping treatments are imposed as a RCBD with a split plot and four replications. Main plots are cover crop treatments. In the post small grains experiment, cover cropping treatments include: no cover control, cereal rye + hairy vetch (34 + 34 kg ha-1), and cereal rye + crimson clover (34 + 22 kg ha-1). In the post corn silage experiment, cover crop treatments include: no cover control, cereal rye (134 kg ha-1) and cereal rye + hairy vetch (101 + 22 kg ha-1). The split-plot treatment is the herbicide program. Herbicide programs include: 1) burndown application only, 2) burndown + pre-emergent residual application, 3) burndown + post-emergent application and 4) burndown + pre-emergent residual application + post-emergent application. Weed microplots are established using the methodology described in the 'Cover Crop Strategies Experiment' for both horseweed and smooth pigweed. An overview of results shows that, such as with the Cover Crop Windows Experiment, cover cropping treatments that produce greater residue more successfully suppress smooth pigweed and other summer annual weed species. Further, including a pre-emergent residual application in the herbicide program can help manage late-emerging horseweed plants or those that have escaped the burndown; however the pre-emergent residual application is rather ineffective against smooth pigweed, which emerges mid-summer in the Mid-Atlantic. For smooth pigweed management, the burndown + post-emergence program is as effective for controlling summer annual weeds as the burndown + pre-emergent residual application + post-emergent application program. Data collection that addresses the ability of cover crops to suppress weeds while influencing other valued ecosystem services provided by the cover crops is ongoing, and results are expected in the early months of 2018.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Bunchek, J.M., J.M. Wallace, M. VanGessel, W. Curran, and D.A. Mortensen. 2017. Optimizing herbicide and cover crop programs for integrated weed management in no-till grain systems. Proceedings Northeast Plant, Pest, and Soils Conf. 2:53
Bunchek, J.M., W.S. Curran, M.J. VanGessel, and D.A. Mortensen. 2017. Optimizing cover crop and herbicide strategies to diversify herbicide resistant weed management in annual grain crops. Proceedings American Society of Agronomy 266-3.
Bunchek, J.M., J.M. Wallace, M. VanGessel, W. Curran, and D.A. Mortensen. Optimizing herbicide and cover crop programs for integrated weed management in no-till soybean. Proceedings Weed Sci. Soc. Am. 57:6.
Curran, W., D. Lingenfelter, and H. Myer. 2017. Cover crop termination timing can affect weed control and crop performance; the pros and cons of planting green. Proceedings Northeast Plant, Pest, and Soils Conf. 2:86
Klodd, A., W. Curran, D. Miller, S. Crawford, D. Lingenfelter, and A. Davis. 2017. Development of an educational mapping tool for documenting and researching the spread of herbicide resistant weeds in the US. Proceedings Northeast Plant, Pest, and Soils Conf. 2:87.
Wallace, J.M., W. Curran, M. VanGessel, D.A. Mortensen, J.M. Bunchek, and B. Scott. Cover crop traits and management strategies influence horseweed suppression in no-till cropping sytems. Proceedings Northeast Plant, Pest, and Soils Conf. 2:84.
Wallace, J.M., W. Curran, M. VanGessel, D.A. Mortensen, and J.M. Bunchek The role of fall cover cropping in diversifying weed management of horseweed in conservation tillage systems. Proceedings Weed Sci. Soc. Am. 57:270.
Wallace, J.M., W. Curran, M. VanGessel, D.A. Mortensen, and J.M. Bunchek 2017. The role of fall cover cropping in diversifying weed management of horseweed in conservation tillage systems. Proceedings Weed Sci. Soc. Am. 57:270.
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Progress 09/01/15 to 08/31/16
Outputs
Target Audience:Our target audience is producers who practice conservation tillage in an intensively managed grain production system within the Mid-Atlantic region. Those stakeholders would primarily include, but are not limited to cash-grain and livestock feed grain operations that typically rely heavily upon herbicides for weed control, including glyphosate-resistant traits. The outcomes of our experiment should also be of interest to producers with similar crop production practices in the Midwestern region. Towards this end, we have included preliminary results from our experiments into extension-outreach programming (listed below) at both Penn State and University of Delaware. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?We have recruited a graduate student (J Bunchek, M.S. degree) to participate in research and extension activities as a part of their graduate programs. In 2016, four undergraduates working in the Curran Lab have participated in research related to this project. How have the results been disseminated to communities of interest?In 2016, we utilized information from research experiments in six extension field day presentations, one college course, two web-based extension outreach articles and seven professional conference presentations. What do you plan to do during the next reporting period to accomplish the goals?There are no changes to the initial project plan.
Impacts
What was accomplished under these goals?
1) Initiated Cover Crop Windows Experiment (2015-2017). In Sept 2015, we initiated field experiments at PSU-RELARC and UD-CREC. This experiment addresses two primary objectives: 1) determine the mechanisms by which selected cover cropping strategies designed for no-till systems influence weed population dynamics, and 2) determine how the length of the cover crop growing season influences weed suppression levels. Cover cropping treatments are being evaluated following small grain production and are imposed as a RCBD with a split-plot and four replications. Main plots are cover cropping strategies. Six cover cropping treatments are planted early September to simulate longer fall growing windows following small grains: 1) cereal rye (134 kg ha-1), 2) spring oats (134 kg ha-1), 3) cereal rye + hairy vetch (34 + 34 kg ha-1), 4) cereal rye + crimson clover (34 + 22 kg ha-1), 5) cereal rye + forage radish (101 + 6 kg ha-1) , 6) spring oats + hairy vetch (34 + 34 kg ha-1 and 7) no cover crop control. Three cover treatments were planted in early October to simulate a shorter fall growing window following summer annual cash crops. These treatments include: 1) cereal rye (134 kg ha-1), 2) cereal rye + hairy vetch (34 + 34 kg ha-1), and 3) cereal rye + crimson clover (34 + 22 kg ha-1). Split plots include cover crop termination timing: 1) cereal rye boot stage, and 2) cereal rye heading stage or when hairy vetch turns reproductive. Weed microplots were established using the methodology described in the 'Cover Crop Strategies Experiment' for both horseweed and smooth pigweed. Data collection methods described in 'Strategies' has been used for horseweed. 2) Initiated Cover Crop IWM Experiments (2015-2017). In Sept 2015, we initiated two field experiments at both PSU-RELARC and UD-CREC. This set of experiments addresses two primary objectives: 1) determine the effects of these winter cover crop strategies on herbicide resistance selection pressure, and 2) determine how managing cover crops for weed suppression influences other valued ecosystem services provided by cover crops. At each site, one experiment is evaluating cover crop treatments following small grains using an early-Sept planting date, which will be terminated and planted to corn in the spring. The other experiment is evaluating cover crops following corn-silage using an early-October planting date, which will be terminated and planted to soybean in the spring. In both experiments cover cropping treatments are imposed as a RCBD with a split plot and four replications. Main plots are cover crop treatments. In the post small grains experiment cover cropping treatments include: 1) no cover control, 2) cereal rye + hairy vetch (34 + 34 kg ha-1), and 3) cereal rye + crimson clover (34 + 22 kg ha-1). In the post corn silage experiment, cover crop treatments include: 1) no cover control, 2) cereal rye (134 kg ha-1) and 3) cereal rye + hairy vetch (101 + 22 kg ha-1). The split-plot treatment is the herbicide program. Herbicide treatments include: 1) burndown application only, 2) burndown + pre-emergent residual application, 3) burndown + post-emergent application and 4) burndown + pre-emergent residual application + post-emergent application. Weed microplots were be established using the methodology described in the 'Cover Crop Strategies Experiment' for both horseweed and smooth pigweed. Data collection that addresses our first objective includes: 1) horseweed and pigweed density and size at the time of each application to quantify cover crop effects on herbicide selection pressure and 2) control efficacy of each herbicide treatment to evaluate cover crop interactions with herbicide efficacy. Data collection that addresses our second objective includes cover crop effects on: 1) potential soil erosion using RUSLE simulations, 2) nitrogen retention, provisioning and leaching potential using methods developed by PSU Kaye lab, 3) cash crop yield, and 4) economic profitability using partial budget analysis. 3) Completed Cover Crop Strategies Experiment. Research results have been summarized for the 2014-2015 growing season. At the PA site, all treatments provided significant horseweed suppression (37 to 97%), which was measured as the percent population decrease relative to the no cover crop control, prior to spring burndown applications. Fertilization increased horseweed suppression across cover crop treatments in comparison to unfertilized plots. High levels of horseweed suppression (81 to 97%) were observed in treatments that included cereal rye. At the DE site, fertilization did not have a significant effect on horseweed suppression. Cover crop treatments that included cereal rye as well as the oats + vetch treatment resulted in significant horseweed suppression (71 to 100%) prior to burndown applications. The winter kill strategies, oats and oats + forage radish, did not differ compared to the control. In evaluations of cover crop traits and performance, we found that fall ground cover 10 weeks after planting and total spring biomass were most predictive of horseweed suppression at the PA and DE sites, respectively. Our PA results suggest that fall fertilization of cover crops may be necessary to maximize weed suppression benefits for horseweed management. However, this practice may increase the potential for nitrate leaching. In comparison to the unfertilized control, fall N retention in fertilized oat or oat mixture treatments increased from 23 to 39 lbs N/ac. Total fall and spring N retention increased 53 to 61 lb N/ac across fertilized rye or rye-mixture treatments in comparison to the control. These results indicate that additional work is needed to identify fall fertilization rates that will maximize suppression of winter annual weeds without contributing to nitrate leaching potential. Cover Crop Windows Experiments & Cover Crop IWM Experiment. The first year of these studies was completed in October 2016 and the second year was initiated in September 2016. Data summary is ongoing and will be completed in the winter of 2017. Our preliminary experiment yielded significant insights into the management of cover crop mixtures to optimize suppression of winter annual weed species.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
Bunchek J, W Curran, D Mortensen, J Wallace, M VanGessel (2016) Integrating cover crops into no-till grain systems to diversify herbicide resistance management. Proceedings of Northeastern Plant, Pest and Soils Conference. Philadelphia PA.
Bunchek J, W Curran, D Mortensen, J Wallace, M VanGessel (2016) Integrating cover crops into no-till grain systems to diversify herbicide resistance management. 6th Annual PSU Sustainable Cropping Systems Symposium [55 attendees]
Bunchek J, W Curran, D Mortensen, J Wallace, M VanGessel (2016) Integrating cover crops into no-till grain systems to diversify herbicide resistance management in the Mid-Atlantic United States. Proceedings of 7th International Weed Science Congress. Prague, Czech Republic.
Curran WS, J Wallace, D Lingenfelter, DA Mortensen, and MJ VanGessel (2016) Is an integrated weed management renaissance or fallacy in our future? Philadelphia, PA: Proceedings of Northeastern Plant, Pest and Soils Conference.
Wallace J, W Curran, M VanGessel, D Mortensen (2016) Cover crop management strategies for improving winter annual weed suppression in Mid-Atlantic no-till cropping systems. San Juan, PR: Proceedings of Weed Science Society of America.
Wallace J, W Curran, M VanGessel, D Mortensen (2016) Fall cover crop strategies for management of horseweed in no-till grain systems. Philadelphia, PA: Proceedings of Northeastern Plant, Pest and Soils Conference.
Wallace J (2016) Cover crops: a tool for the critical period of weed control in conservation tillage systems? Penn State Plant Science Seminar. 7 Oct 2016
- Type:
Websites
Status:
Published
Year Published:
2016
Citation:
Curran WS, Wallace J, Bunchek (2016) Integrating cover crops to improve management of herbicide resistant weeds in no-till soybean. Penn State Field Crops Newsletter. 14 Sep 2016.
http://extension.psu.edu/plants/crops/news/2016/09/integrating-cover-crops-to-improve-management-of-herbicide-resistant-weeds-in-no-till-soybean
Klodd A, W Curran, J Wallace, R Champagne (2016) Managing cover crops for weed control in organic and conventional systems requires careful planning and management. Penn State Field Crops Newsletter. 4 October 2016. http://extension.psu.edu/plants/sustainable/news/2016/fall-2016/managing-cover-crops-for-weed-control-what-we2019ve-learned-from-organic-and-conventional-systems
- Type:
Other
Status:
Other
Year Published:
2016
Citation:
Wallace, J (Fall 2016). AGRON 438 Principles of Weed Ecology and Management. Field Trip: Integrative Weed Management in Conservation Tillage Systems. [22 students]
Bunchek J, Wallace J, W Curran (2016) Integrating cover crops and herbicide programs for management of herbicide resistant weeds. Penn State Weed Control Tour, Rock Springs PA, Russell E. Larsen Agricultural Research Center. July 2016 [55 attendees].
Curran WS (2016) The obnoxious pigweeds in Pennsylvania. Presentation to key stakeholder groups, Jan. 19, 2016. 50 people.
Curran WS (2016) Update on the obnoxious pigweeds in Pennsylvania. Presentation to Penn Ag Industries, Mar. 17, 2016. 25 people.
Curran, WS, AE Klodd (2016) IWM programs for managing herbicide resistant weeds. Penn State Diagnotic Clinic, July 21 and 22, 2016.
Wallace J, W Curran (2016) Principles of herbicide management of cover crop establishment and termination. Cover Crops in Concords Workshop. Portland NY. [55 attendees]
Wallace J (2016) The latest on herbicide resistant weeds in PA field crops. Penn State Extension: Crops Day Western PA. Butler PA. [45 attendees]
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Progress 09/01/14 to 08/31/15
Outputs
Target Audience:Due to the funding cycle relative to the proposed field experiments, we initiated a preliminary experiment in fall 2014 to address several factors related to the proposed objectives. In fall 2015, we have initiated the full proposed project. Consequently, extension outreach activities related to the project will begin in the summer of 2016. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?In the spring of 2015, we recruited a graduate students (MS) to participate in research and extension activities as a part of their graduate programs. How have the results been disseminated to communities of interest?The results of our preliminary experiment were used in three extension education events: VanGessel M (2015) Integrating cover crops for weed management. Delaware Soil Health Field Day - Sussex County Conservation District. [60 attendees] VanGessel M (2015) The intersection of cover crops and weed control. Mid-Atlantic Crop Management Conference. [80 attendees] Wallace J, W Curran, D Lingenfelter (2015)Integrating cover crops and herbicide programs for management of herbicide resistant weeds. Ag Progress Days, Rock Springs PA, Russell E. Larsen Agricultural Research Center. Aug 21-23 [75 attendees]. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Three field experiments have been initiated to our address objectives. Cover Crop Strategies Experiment (2014-2016). We initiated a preliminary experiment in the Fall 2014 to address: 1) cover crop mixture seeding rates, 2) weed data collection methods and 3) the role of fertility management in cover crop performance. Field experiments focused on evaluation of cover crop strategies for winter annual weed management and were located at PSU-RELARC in central PA and at UD-CREC near Georgetown DE. Cover cropping treatments were evaluated following small grain production and were imposed as a RCBD with a split-plot and four replications. Main plots were cover crop treatments, which include 18 combinations of one-, two- and three-species mixes of cover crops that include winter-hardy species (cereal rye, Austrian winter pea, crimson clover, hairy vetch) and winter-kill species (spring oats, forage radish). A subset of treatments was identified for focus on cover crop performance and weed suppression: no cover, cereal rye (134 kg ha-1), spring oats (134 kg ha-1), cereal rye + hairy vetch (67 + 22 kg ha-1), cereal rye + forage radish (67 + 6 kg ha-1), spring oats + hairy vetch (67 + 22 kg ha-1), spring oats + forage radish (67 + 6 kg ha-1). Split-plots were fertility treatments: 0 or 67 kg N ac-1 using AMS. We evaluated fertility as a management strategy for optimizing weeds suppression from cover crop mixtures. Cover crops were planted using a no-till grain drill following burndown and fertilizer applications in early September, and were terminated at the cereal rye boot stage using glyphosate + 2,4-D (1.26 + 0.56 kg ha-1). Locally-collected horseweed seed was distributed in permanent microplots (0.50 m2) at an average rate of 5,400 seeds m-2. Cover crop ground cover was visually estimated by species 5 and 10 weeks after planting (WAP). Cover crop biomass (kg ha-1) was collected by species 10 WAP and at spring burndown. Horseweed density and size was quantified at 10 WAP, at spring-burndown and 4 weeks after spring-burndown treatments. At PSU-RELARC, the addition of fertilizer (67 kg ha-1) had a significant effect on cover crop biomass 10 WAP across cover crop treatments, resulting in decreased horseweed density (216 plt m-2) compared to cover crops without fertilizer (608 m-2). Within fertilized plots, each cover crop treatment significantly decreased horseweed density 10 WAP by at least 45% compared to the control. Cereal rye + radish resulted in the greatest decrease (86%). Within unfertilized plots, cover crops did not decrease horseweed densities 10 WAP relative to the control, but did decrease the average diameter of horseweed rosettes. Similar trends were observed at spring burndown. In fertilized plots, cover crop treatments significantly decreased horseweed density relative to the control except for oats + vetch. Notably, horseweed density in the rye and rye + radish treatments were 16 and 32 plt m-2, respectively, compared to 340 plt m-2 in the control. Horseweed densities were low across the UD-CREC site 10 WAP, which precluded analysis of cover crop effects. At spring burndown, cover crop treatments influenced horseweed density similarly across fertilizer treatments. Only rye + vetch significantly decreased horseweed density (0 plt m-2) compared to the control (80 plt m-2), though the rye and oats + vetch treatments resulted in high levels of horseweed suppression (< 10 plt m-2). Our results suggest that fall-planted cover crops have the potential to significantly suppress horseweed populations, thereby reducing herbicide selection pressure. General trends suggest that winter-hardy cover crops that produced high levels of ground cover 5 WAP provided greater horseweed suppression than winter-kill cover crops. Our results also indicate that fertilization of cover crops may be necessary to maximize weed suppression benefits of cover crops for horseweed management. Cover Crop Windows Experiment (2015-2017). In Sept 2015, we initiated field experiments at PSU-RELARC and UD-CREC to address two primary objectives: 1) determine the mechanisms by which selected cover cropping strategies designed for no-till systems influence weed population dynamics, and 2) determine how the length of the cover crop growing season influences weed suppression levels. Cover cropping treatments are being evaluated following small grain production and are imposed as a RCBD with a split-plot and four replications. Main plots are cover cropping strategies. Six cover cropping treatments are planted early September to simulate longer fall growing windows following small grains: 1) cereal rye (134 kg ha-1), 2) spring oats (134 kg ha-1), 3) cereal rye + hairy vetch (34 + 34 kg ha-1), 4) cereal rye + crimson clover (34 + 22 kg ha-1), 5) cereal rye + forage radish (101 + 6 kg ha-1) , 6) spring oats + hairy vetch (34 + 34 kg ha-1 and 7) no cover crop control. Three cover treatments were planted in early October to simulate a shorter fall growing window following summer annual cash crops. These treatments include: 1) cereal rye (134 kg ha-1), 2) cereal rye + hairy vetch (34 + 34 kg ha-1), and 3) cereal rye + crimson clover (34 + 22 kg ha-1). Split plots include cover crop termination timing: 1) cereal rye boot stage, and 2) cereal rye heading stage or when hairy vetch turns reproductive. Weed microplots will be established using the methodology described in the 'Cover Crop Strategies Experiment' for both horseweed and smooth pigweed. Data collection methods described in 'Strategies' will be used for horseweed. Additional data for horseweed and smooth pigweed will be collected to evaluate cover crop effects on weed population dynamics. Cover Crop IWM Experiments (2015-2017). In Sept 2015, we initiated two field experiments at both PSU-RELARC and UD-CREC. This set of experiments addresses two primary objectives: 1) determine the effects of these winter cover crop strategies on herbicide resistance selection pressure, and 2) determine how managing cover crops for weed suppression influences other valued ecosystem services provided by cover crops. At each site, one experiment is evaluating cover crop treatments following small grains using an early-Sept planting date, which will be terminated and planted to corn in the spring. The other experiment is evaluating cover crops following corn-silage using an early-October planting date, which will be terminated and planted to soybean in the spring. In both experiments cover cropping treatments are imposed as a RCBD with a split plot and four replications. Main plots are cover crop treatments. In the post small grains experiment treatments include: 1) no cover control, 2) cereal rye + hairy vetch (34 + 34 kg ha-1), and 3) cereal rye + crimson clover (34 + 22 kg ha-1). In the post corn silage experiment, cover crop treatments include: 1) no cover control, 2) cereal rye (134 kg ha-1) and 3) cereal rye + hairy vetch (101 + 22 kg ha-1). The split-plot treatment is the herbicide program. Herbicide treatments include: 1) burndown application only, 2) burndown + pre-emergent residual application, 3) burndown + post-emergent application and 4) burndown + pre-emergent residual application + post-emergent application. Weed microplots will be established using the methodology described previously for both horseweed and smooth pigweed. Data collection that addresses our first objective will include: 1) weed density and size at the time of each application to quantify effects on herbicide selection pressure and 2) control efficacy of each herbicide treatment to evaluate interactions with herbicide efficacy. Data collection that addresses our second objective will include cover crop effects on: 1) potential soil erosion using RUSLE simulations, 2) nitrogen retention, provisioning and leaching potential using methods developed by PSU Kaye lab, 3) cash crop yield, and 4) economic profitability using partial budget analysis.
Publications
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