Using cover crops and crop diversity to optimize ecologically based weed management

Final Report for LNE05-216

Project Type: Research and Education
Funds awarded in 2005: $98,732.00
Projected End Date: 12/31/2008
Matching Non-Federal Funds: $70,084.00
Region: Northeast
State: Pennsylvania
Project Leader:
Willaim Curran
Penn State University
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Project Information

Summary:

This project included two primary objectives. First, we conducted educational programs focused on cover crops and ecologically-based weed management that included field demonstrations. Second, we conducted research at university research farms and in producer’s fields to assess the presence of potential weed seed predators. A total of 12 field days were conducted in Maine and Pennsylvania directly reaching about 700 individuals. In the follow-up project survey conducted in fall of 2008, respondents reported that after attending one or more activities offered in this project, 3% had transitioned to organic production and 19% were more interested in transitioning to organic production, 47% were thinking about how cover crops and crop rotation fit into organic production, 41% were using cover crops for weed suppression and 62% of the individuals were looking much harder at using cover crops for weed suppression, 21% were interested in cover crop roller design and use, 40% were considering the effects of tillage and mowing for weed suppression, 15% were considering how to better use seed predators to suppress weeds, 31% had reduced pesticide use, 36% planted cover crops to supplement cash crop fertility, 55% used cover crops to improve the soil, 31% used cover crops to conserve beneficial organisms and 48% were thinking more about beneficial soil organisms, 33% used a new cover crop species or mixture and 62% were interested in discovering and learning about new cover crop species, about 40% had reduced the amount of tillage they used as well as reducing fuel use, and 31% were trying no-till and 50% were interested in learning more about no-till equipment. A total of 52% had adopted or promoted more sustainable ag practices on their farm or in their work. Finally, 88% of the respondents felt the changes they had made in the last 3 years improved the environment, 57% said it made them more profitable, and 36% thought it provided greater social benefit to their operation or in their work (see Appendices for complete survey results).

The seed predation research focused on two potentially key carabid beetles that are known weed seed predators. Both are commonly found either in Pennsylvania or Maine and both were more prominent towards the middle and end of summer. In Pennsylvania, the activity density (abundance) work suggested that cropping systems with little or no late summer tillage or mowing encourage H. pensylvanicus populations. In Maine, this research suggested that while the presence of vegetation alone encourages adult H. rufipes populations, some level of soil disturbance was needed to achieve even higher densities of the beetles. Although the activity density experiments focused on these two carabids, the seed predation work showed that numerous organisms likely feed on weed seeds. Seed predation experiments conducted in Pennsylvania showed giant foxtail seed removal (feeding) rates between 40 and 90% over a 14-day period. We observed at least 60% giant foxtail removal throughout the summer in three of five sampling periods. Distinct early and late summer peaks did not occur in our research further suggesting that several seed predators likely contributed to seed losses observed. Observations during this experiment suggest that higher frequencies of tillage could decrease the level of H. pensylvanicus activity density in certain crops. However, carabid beetles may not prefer one cropping system throughout the entire growing season but may tolerate a specific crop type during a specific time in the season. At Penn State, most of the predation was caused by insects and seeds were consumed during the entire summer. At Cedar Meadow Farm in Southeast Pennsylvania, vertebrates (mice and other rodents) probably played a larger role, although insect predation was also detected. These experiments clearly showed that a number of organisms consume weed seeds and that it can occur in different cropping systems and during most periods of time during the summer. Both the presence of plant cover and reduced tillage at key periods of time and especially later in summer should help conserve and promote weed seed predators in northeast cropping systems.

Introduction:

This project built on activities being conducted as part of a USDA Transition to Organic (Transition) funded grant and a Northeast Region Integrated Pest Management (NEIPM) Research and Extension grant. A component of both the Transition and NEIPM studies involves the characterization of soil surface dwelling insect populations and how these populations may be impacted by various cultural weed management strategies such as cover cropping and crop rotation as well as by mechanical weed control methods. The NESARE grant was building on this work by expanding our research efforts at understanding the impact of cropping system diversity and disturbance on weed seed predation by beetles. The education project within this grant focused more broadly on demonstrating how cover crops and increased crop diversity promote ecologically-based weed management (EBWM). On-farm demonstrations and field days were focused on cover crop management, cropping sequence, tillage, weed seed predation, and other cultural management impacts on weed management. We conducted university-based and on-farm research and demonstrations that examine the relationship between cultural practices, abundance and activity of weed seed predators, weed populations and crop yield in sustainable crop production systems. Farmers, extension agents and other agricultural professionals attended field days to learn first-hand about the opportunities and benefits for EBWM strategies.

Performance Target:

Of the 500 farmers attending a field day, 25 will adopt some aspect of ecologically based weed Management (EBWM) identified through this research. Of the 100 extension and other agricultural professionals attending field days, 50 extension and other education professionals will incorporate knowledge into their educational programming, and 15 will work with farmers or farm youth to actively promote EBWM.

This performance target was mostly achieved, although we did not accomplish documenting some of these very specific targets and especially the final target of 15 education professionals working on EBWM’s with farmers. We believe this is happening on the ground, but have not documented this goal.

Cooperators

Click linked name(s) to expand
  • Eric Gallandt

Research

Materials and methods:

Ecologically-based Weed Management Field Days and Demonstrations.

Selected farmers cooperated with the project team to organize on-farm sites to demonstrate the concepts and techniques underpinning the practices of cover cropping and increasing crop diversity. Twelve field days show cased innovative weed management techniques exploiting cover crops and crop diversity as a focus of the on-farm demonstrations. Extension educators, other ag professionals, secondary and post secondary educators, and farmers observed the impacts of diversification of cropping systems on weed control and weed seed bank dynamics. For on-farm demonstrations, two or three treatments were included. The trials consisted of larger plots that were sized in widths to accommodate the host farmer’s equipment (see plot diagrams in appendices). The trials were replicated four times laid out as randomized complete blocks. Field days were conducted at times when the educational message was most clearly seen in the field. We evaluated the success of the educational activities through attendance and through evaluations conducted at each field day event. In December 2007, twenty surveys were sent to Maine growers who had attended the University of Maine Cooperative Extension and Maine Organic Farmer’s and Gardeners Association Farmer-to-Farmer Conference. These were farmers who had attended a special session focused on innovative cultivation equipment from Europe, and thus presumably had an interest in weeds and weed management. Six completed surveys were returned by the end of the summer, and although a relatively small sample size, they are our best source of detailed local information at this time. The summarized survey results are presented in the Appendices. In addition, a follow up survey was sent out to 170 individuals that attended Pennsylvania events. Of this group, 58 answered the electronic survey. Results from the evaluations are provided in the results section of this document and the complete results are available in the Appendices.

Beetle activity density and seed predation research.

Pitfall trap sampling methods were used on farms to document the impact of cover crop management on the activity/density (abundance) of weed seed predators. Pitfall traps consisted of a plastic container with a polystyrene cup filled about a third full with ethylene glycol (killing agent) placed in the bottom of the plastic container. The top half of a 2 liter plastic soda bottle was inverted placed in the plastic container to direct invertebrate (mostly insect) organisms into the specimen cup (Figure 1A). Pitfall captures were based on a 72-hour collection period. Pitfall traps were collected and taken back to the laboratory to determine their contents. Pitfall trapping was used extensively at both Penn State and Maine research farms to characterize the abundance of seed predators in different cover cropping systems during the summer. Pitfall trapping also occurred at Cedar Meadow and Village Acres farms in support of the field day activities

In addition, seed predation (feeding and removal) potential was assessed at the Penn State Rock Springs farm and at Cedar Meadow farm. Open and restricted entry cages were placed in different treatments or fields. Restricted traps (Figure 1B) consisted of galvanized metal hardware cloth (3.3 by 3.3 cm openings) prevented access by small mammals and birds, but allowed most invertebrates. Open traps (Figure 1C) were constructed without metal hardware cloth which permitted access to vertebrate (small mammals) and invertebrate seed predators. The open traps were accessible by both ground dwelling vertebrates and invertebrates. Within each trap a Petri dish was placed bottom side up and buried so that the dish was flush with the soil surface. The surface of the Petri dish was covered with double-sided indoor/outdoor carpet tape and 100 giant foxtail (Setaria faberi Herrm.) seeds were randomly sprinkled on the tape surface. A small amount of field soil was sprinkled on the tape to remove stickiness and better mimic the soil surface (Figure 1D). Weed seed predation rate was based on the removal of giant foxtail seed over a 14-day period repeated several times during the summer. During the course of the summer, traps were moved then returned to their original position when agronomic management practices were preformed (i.e. cultivation or mowing).

Research results and discussion:

Ecologically-based Weed Management Field Days and Demonstrations.

In Pennsylvania and Maine, county extension educators and select farmers were contacted and asked for input in identifying potential farmer participants. In Pennsylvania, the Pennsylvania Association for Sustainable Agriculture (PASA) was also consulted about potential farms. Three family farms in Pennsylvania and two in Maine were identified and contacted to participate. In addition, the university research farms in both states also served as farm locations bringing the total to seven. Field demonstrations and research were established at six of the seven farms in the fall of 2005 for the field day activities in 2006. In Maine, an organic dairy and an organic vegetable farm were selected for field demonstrations. In Pennsylvania, two organic vegetable farms/CSA and a conventional no-till vegetable-grain-livestock farm were selected for the demonstrations and field days. As mentioned previously, experiment station farms also were utilized. The primary emphases in the demonstrations were 1.) showing how the size of the weed seed bank influences effective control, 2.) the impact of cover crops on weed germination and establishment, and 3.) timing of tillage and cover crop termination and its impact on weed control and, 4.) mechanical vs. chemical control of cover crops. These factors varied depending on the farm operation.

Several Pennsylvania PI’s traveled to Maine in September, 2005 to view Maine activities and discuss the 2006 expected activities and outcomes with the Maine PI’s. From 2005 to 2007, a total of 8 educational field days were held in Pennsylvania and 4 in Maine that focused on the role of cover crops for ecologically-based weed management. Pennsylvania field days were co-hosted by the PASA. Research and/or demonstration plots were utilized at each location to help communicate the educational message. Field days took place at the PSU Russell E. Larson Agricultural Research and Education Center near Rock Springs and on three farms in different regions of the state (Charlestown Cooperative farm in Chester County, Cedar Meadow farm in Lancaster County, and Village Acres Organic farm in Mifflin County). In Maine, a field day was held at the University of Maine Roger’s Farm in Stillwater and at three Maine farms, one diversified organic vegetable farm, and two organic dairies: The Peace meal farm in Dixmont, the Morrison farm in Charleston, and the Perkins farm. In 2007, a cover crop summit was held at the Penn State Rock Springs Research Farm to showcase some of the cover crop and weed management research taking place. About 90 people attended the field day. In Maine, an IPM/Conservation Farm Tour/Workshop for Conservation Professionals was conducted in 2007. This 1.5 hour session focused on identification and critical life-history stages of annual weeds that contribute to design and implementation of ecologically-based management. A total of 25 professionals attended the session.

A number of topics were presented at these events including weed seed predation and the use of a seed predator test kit (see Appendices). Seed predator test kits were assembled and provided to interested attendees in both states. Along with this, several fact sheets and lesson plans were developed for educators. About 675 individuals attended one or more of the events over the life of the project (2005-2007). Attendees included farmers, vo-ag teachers, cooperative extension personnel, and other ag professionals. Results from cover crop and weed management research were presented at the field days and attendees had an opportunity to view field experiments/ demonstrations. Of particular interest to the group was the seed predation work and the potential impact of ground beetles, the focus of our seed predation research.

Maine hosted the Northeast SARE PDP/AC summer tour/meeting in 2006. Two of the farm visits on the stop participated in this project. One stop at the Perkins farm included a presentation and demonstration of the weed predator test kits and a brief presentation by Bill Curran and Rick Kersbergen. The SARE group also visited Peacemeal farm, also a cooperator on the project

Evaluation Summaries.

Evaluations were conducted at most field day activities and six of the eight PA events are summarized here. A total of 162 surveys were returned from the six events. This is not as good a return rate as we had hoped. We learned during these events that building extra time into the program for evaluation is critical. Also, having an incentive to return the evaluations can be important. At one event, the participants received ice cream after they returned the evaluation which increased the return rate.

To summarize the six events (n=162), 94 individuals in attendance were full (22%) or part-time (25%) farmers and 36% of those in attendance were educators and/or researchers, 5% were government agency employees, and 6% were from environmental organizations or NGO’s and 17% were classified as other which included home gardeners, retired, farm owner/landlord, organic certifier, etc. For the farmers, 12% were certified organic, 12% were organic, but not certified, 11% were transitioning to organic, 9% had a mixed operation (conventional and organic), and 5% called themselves conventional. When asked how likely they were to make a change as a result of attending the field day, 34% said very likely, 26% moderately likely, 15% somewhat likely and only 6% were not likely.

At the field day hosted by Steve Groff at Cedar Meadow Farm, over 200 people were in attendance. Of the 46 survey respondents from the no-till and cover crop field day, 42% reported that they were moderately interested in learning more about the influence of planting date on weed emergence periods, and 49% were moderately interested in weed emergence timing and duration as influenced by weed species, 51% of respondents were definitely going to seek more information on the design and comparison of cover crop rollers. Education of producers to increase their use of cover crops in their management practices requires information on the various species and their best uses. Over half the survey respondents reported that they were interested and intended to seek more information on cover crop selection and management. As interest grows in the area of no-till management, of the 45 survey respondents; 45% were interested in learning more about no-till planters, 39% intended to seek more information on no-till drills and 45% were moderately interested in the use of cover crop rollers. Survey respondents also mentioned a few topic areas they would like to learn more about including; weed and nutrient control for smaller-scale operations, more insect and disease identification, using mixed cover crop species to provide fertility for cash crops, availability of cover crop seed and farmscaping techniques.

At the Village Acres hosted field day, an organic CSA operation, a good indicator if the content of a field day program was beneficial is to gauge participant understanding of a topic before and after the event. Before the field day 33% of the 30 field day respondents indicated that they had minimal to moderate knowledge of soil fertility management, testing and interpretation. After the field day 53% reported a moderate understanding and 40% considerable understanding. Similar results were indicated with the topic of the effects of cover crop and residue management on soil quality. Before the field day 42% reported a moderate understanding and 19% a considerable understanding. After the field day 45% had moderate and 48% considerable understanding.

At the four of six field days that had a very similar focus and audience (more organic oriented individuals), 12% of survey respondents reported a non-existent understanding of both the effect of cover crop and residue management on weed suppression and 43% a lack of understanding of the role of seed predators on weed suppression prior to the workshop. After the program 55% had moderate understanding of the role cover crops and residues play in weed suppression and 59% understood more about weed seed predators, such as ground beetles and how they can also play an important role in weed suppression. Over the next year 55% of survey respondents at four of the SARE sponsored field days indicated they were considerably interested in finding more information on the effects of cover crop management on weed suppression and 42% were interested in more about the role of weed seed predators.

When offering field day programming it is important to be sure the content offered is of use to participants and they feel the investment made in coming to the tour is worthwhile. Of the 162 survey respondents, 64% reported the field days were a good use of their time. In the age of increased communication via electronic sources, it is often a challenge to discern best methods to use to promote an event to a wide audience. When coordinating promotion it is always good to reach out to fellow organizations with members that may be interested in the field day programming; such as Cooperative Extension, PASA and various regional Extension newsletters. Of 162 survey respondents from the six SARE sponsored field days, 41% learned about the event from the PASA field day calendar, while 20% heard about it through Cooperative Extension and 15% via a newsletter. A complete survey summary and example surveys can be found in the Appendices section.

A final project survey was conducted during the fall of 2008 in Pennsylvania to capture potential impacts from those that attended the educational programs over the life of the project. Of the 170 individuals contacted, 58 responded to the electronic survey (Survey Monkey); 53% were full or part-time farmers, 22% were educators and researchers, 31% were government employees, and 14% were ag service providers. The remainder was students, NGO employees, media/journalists, or other. Changes that had occurred after attending one or more activities included: 3% had transitioned to organic production, 41% were using cover crops for weed suppression, 40% were considering the effects of tillage and mowing on weed suppression, 15% were considering how to better use seed predators in weed suppression, 31% had reduced pesticide use, 36% planted cover crops to supplement cash crop fertility, 55% used cover crops to improve the soil, 31% used cover crops to conserve beneficial organisms, 33% used a new cover crop species or mixture, about 40% had reduced the amount of tillage they used as well as reducing fuel use, and 31% were trying no-till. A total of 52% had adopted or promoted more sustainable ag practices on their farm or in their work.

Participating in this project had stimulated the participant’s interest in a number of ecologically-based farming practices. Of the total, 19% were more interested in transitioning to organic production and 47% were thinking about how cover crops and crop rotation fit into organic. Of the total respondents, 62% were looking much harder at using cover crops for weed suppression with 62% interested in new cover crop species, 21% were interested in cover crop roller design and use, 48% were thinking more about beneficial soil organisms, and 50% were interested in no-till equipment.

Finally, 88% of the respondents felt the changes they had made in the last 3 years improved the environment, 57% said it made them more profitable, and 36% thought it provided greater social benefit to their operation or in their work.

Outreach Publications.

A number of publications were developed for these events (copies are included in the Appendices):

-Ecologically-based weed management: strategies for managing weeds without herbicides by E. Gallandt and R. Kersbergen.

-Cover crops and weed management by W. Curran
-When do weeds wake up by D. Mortensen, W. Curran, M. Ryan, A. Hulting, and S. Mirsky.

-Quackgrass management on organic farms by H. Westwood, K. Cox, E. Gallandt, E. Sideman, and R. Kersbergen.

-Weed seed predators: potential contributors to weed control by M. Murray, W. Curran, D. Mortensen, M. Barbercheck, and E. Gallandt.

-Ground beetles: potential for biological control of weeds by M. Murray and W. Curran.

Seed Predator Test Kits.

Seed predator test kits were assembled and distributed to interested individuals at several field day events. Directions for use were included in the weed seed predator factsheet and in a lesson plan developed for Vo-Ag teachers.

Vo-Ag Teacher Lesson Plans.

Lesson plans were developed for and distributed to about 35 Vo-Ag teachers at a field day in 2006. The following lesson plans were presented and distributed. They are provided in the Appendices.

-Weed identification
-Mechanical weed control: white thread stage
-Weed seed predation

Distribution of European Cultivation Handbooks
During the Maine PI’s sabbatical in Denmark he collaborated with some of Europe’s foremost authorities on physical and cultural weed control, including a group from Wageningen University Applied Plant Research in the Netherlands. A particularly relevant publication from this group is Practical Weed Control, which we imported and distributed to 30 farmers at the Farmer-to-Farmer Conference.

Beetle Activity Density and Seed Predation Research.

Weed seed predation trials were conducted at both university research farms during 2005 and seed predator abundance was assessed on select participant farms. The primary purpose in the participant farm work was to characterize potential seed predators in producer’s fields for discussions during the field days.

The more abundant of the ground-dwelling invertebrates observed at Penn State was Harpalus pensylvanicus, a known weed seed predator found in much of the northeastern United States. H. pensylvanicus had peak activity density in the five cropping systems tested (buckwheat/brassica/buckwheat rotation, pea-oat/rye-vetch rotation, organic soybean, clover-oat mix, and a fallow control) beginning in August for both the 2004 and 2005 (Figure 2). In the spring and early summer, H. pensylvanicus showed little preference between crops, while in late summer and early fall, activity density was highest in the cropping systems with little soil disturbance. This corresponds to when adult carabids are in one of their most vulnerable stages (breeding and reproducing) and probably prefer habitats with low disturbance. The activity density in the soybean in September, also a low disturbance treatment, increased slightly or stayed the same. These results suggest that cropping systems with little or no late summer tillage or mowing should encourage H. pensylvanicus populations.

Maine’s dominant invertebrate weed seed predator was the ground beetle Harpalus rufipes. Maine compared H. rufipes abundance in four additional cover crop-based weed management systems (buckwheat/brassica/buckwheat rotation, pea-oat/rye-vetch rotation, snap beans/rye-vetch rotation, and a clover-oat mix) to a fallow control. Significantly more beetles were found in the pea-oat/rye-vetch rotation than in the other cover crop and fallow systems. In comparison with the other systems, the pea-oat system is intermediately disturbed. In contrast, the fallow control and buckwheat/brassica/buckwheat rotation endure greater soil disturbance while the snap beans/rye-vetch rotation and clover-oat mix receive less. This suggests that while the presence of vegetation alone encourages adult H. rufipes populations, some level of soil disturbance is needed to achieve even higher densities.

In 2005, beetle activity density and seed predation was also assessed at Cedar Meadow Farm in a rye/hairy vetch tomatoes rotation and a red clover/hairy vetch/rye squash rotation. Pitfall trapping took place from June to August, but potential invertebrate seed predators at Cedar Meadow Farm were few in number. Unlike Penn State, trap type was significant at Cedar Meadow Farm. Approximately 79% of seed predation occurred in the open trap while about 60% took place in the closed or restricted trap. This implies that vertebrates are a significant contributor to seed predation at Cedar Meadow Farm. The largest amount of seed predation occurred in the beginning of June and steadily decreased until the last sampling period in August . The red clover/hairy vetch/rye-squash rotation had approximately the same amount of seed predation occurring throughout the duration of sampling, while seed predation rates in the rye/hairy vetch-tomato rotation steadily decreased over time (Figure 3). No-till plots with dense, continuous amounts of canopy and ground residue from the combination of three cover crops may have created a more favorable predator habitat increasing seed predator abundance. The cover crops produced concealment for larger seed predators such as rodents, allowing more forging to occur. Predation rates followed the trend of greater predation rates around mid summer and decreasing rates as winter approached. Seed predation rates in the rye/hairy vetch-tomato rotation may have decreased gradually over time due to the ground residue slowly decomposing and the rows of tomatoes creating very little protection and cover for seed predators.

At the Rock Springs farm in 2005, average giant foxtail seed predation varied through the growing season from 38 to 63% (Figure 4). Unlike the Cedar Meadow results, trap type did not affect predation suggesting that vertebrates played a minor role in seed predation in this study and that invertebrates were the primary predators. Rates of seed predation were similar for three of five sampling periods. Predation rates dropped in the late July and September sampling periods. Tillage or low surface residue conditions in between cover crops probably played a role in the decreased predation observed. In addition, comparatively high predation rates in June suggest that predators other than H. pensylvanicus contribute to seed losses, since beetle abundance in June was relatively low. Also the abundance of other food sources during the sampling periods could have influenced giant foxtail seed predation.

In this research, we observed at least 60% giant foxtail predation throughout the summer in three of five sampling periods. Distinct early and late summer peaks did not occur in our research further suggesting that several seed predators likely contributed to the seed losses observed. Observations during this experiment suggest that higher frequencies of tillage could decrease the level of H. pensylvanicus activity density in certain crops. However, carabid beetles may not prefer one cropping system throughout the entire growing season but may tolerate a specific crop type during a specific time in the season. For H. rufipes, greater abundance in an intermediately disturbed cropping system suggests that while the presence of vegetation alone encourages adult beetle populations, some level of soil disturbance may be beneficial in achieving even higher beetle densities.

Participation Summary

Education

Educational approach:

Gallandt, E. and R. Kersbergen. 2006. Ecologically-based Weed Management, prepared for distribution at program-sponsored field days and tours College of Natural Sciences, Forestry, and Agriculture, University of Maine, Orono.

Westwood, H., K. Cox, E. Gallandt, E. Sideman, and R. Kersbergen. 2008.
Quackgrass, Management on organic farms. Motivated by our cover cropping systems experiment which indicated an increase in quackgrass abundance in response to full-season or two-year cover cropping practices, this bulletin was co-authored by two University of Maine Sustainable Agriculture undergraduates, personnel from University of Maine Cooperative Extension, and the Maine Organic Farmers and Gardeners Association, and the Maine Project PI. The publication aims to present research-based information to growers, focusing on practical implications for management, but with a clear emphasis on the need to understand the biology of weeds to optimally deploy ecologically-based strategies.

Mortensen, M., W. Curran, M. Ryan, A. Hulting, and S. Mirsky. 2006. .Weed germination periodicity: When do weeds wake up? Dept. Crop & Soil Sciences, College of Agricultural Sciences, University Park, PA 16802.

Murray, M., W. Curran, D. Mortensen, M. Barbercheck, and E. Gallandt. 2006. Weed seed predators: potential contributors to weed control. Dept. Crop & Soil Sciences, College of Agricultural Sciences, University Park, PA 16802.

Murray, M. and W. Curran. 2006. Ground beetles: potential for biological control of weeds. Dept. Crop & Soil Sciences, College of Agricultural Sciences, University Park, PA 16802.

Murray, M. Weed identification lesson plan. 2006. Dept. Crop & Soil Sciences, College of Agricultural Sciences, University Park, PA 16802.

Murray, M. Mechanical weed control: white thread stage lesson plan. 2006. Dept. Crop & Soil Sciences, College of Agricultural Sciences, University Park, PA 16802.

Murray, M. Weed seed predation lesson plan. 2006. Dept. Crop & Soil Sciences, College of Agricultural Sciences, University Park, PA 16802.

—Peer-reviewed

1.Gallandt, E.R. (2006). How can we target the weed seedbank? Weed Science 54, 588-596.

2.Gallandt, E.R., and Weiner, J. (2007). Crop-weed competition. In “Encyclopedia of Life Sciences”. John Wiley & Sons, Ltd., Chichester, West Sussex, UK.

3.Shearin et al. Cover Crop Effects on the Activity-Density of the Weed Seed Predator Harpalus rufipes (Coleoptera: Carabidae). Weed Science (2008) vol. 56 (3) pp. 442

4.Shearin et al. Direct Effects of Tillage on the Activity Density of Ground Beetle (Coleoptera: Carabidae) Weed Seed Predators. Environmental Entomology (2007) vol. 36 (5) pp. 1140-1146.

—Under development

5.Ward, M. W. Curran, D. Mortensen, and M. Barbercheck. Activity Density and Weed Seed Predation by Potential Weed Seed Predators in Five Cropping Systems.

—Abstracts/Proceedings

1.Curran, W.S. and M.M. Ward. 2008. Is Harpalus pensylvanicus activity density synchronized with giant foxtail? Abstr. WSSA, 48:62.

2.Curran, W.S., A.G. Hulting, R.J. Hoover, M. E. Barbercheck, C. Reberg-Horton, and E. R. Gallandt, Ecologically Based Weed Management Principles: Integrating Research and Education. 2007. Weed Sci. Soc. Am. Abstr. 47:62.

3.Murray, M., S. Mirsky, W. Curran, D. Mortensen and E. Gallandt. 2006. Threshold-based Cover cropping Strategies for Weed Management. Nat’l IPM Conference, St. Louis, MO.

4.Murray, M., W. Curran, M. Barbercheck, and D. Mortensen. 2006. Weed seed predation by ground beetles. Proc. NEWSS 60:55.
5.Mirsky, S. B., M. J. Murray, W. S. Curran, D. A. Mortensen, and M. E. Barbercheck. 2006. Incorporating cover crops for weed management. Abstr. WSSA 45:259.

6.Murray, M., W. Curran, D. Mortensen, and M. Barbercheck. 2005. Ecological Weed Management: The Role of Ground Beetles in Weed Seed Predation. Proc. NEWSS 59:126.

Meetings (Invited and volunteered Presentations)
A number of presentations were made by the project participants to various groups during the course of this project. These included numerous presentations on the management of cover crops and ecologically-based weed management at the educational events that were a direct product of this project, but also presentations at conferences, workshops, and other meetings that were not directly a part of this project.

Examples provided below:

1.A multiple stress approach to managing the weed seedbank. Northeast Organic Farming Association-New York 26th Annual Winter Farming & Gardening Conference, Saratoga Springs, NY (January 25, 2008). – Gallandt.

2.Innovations in physical weed control from Europe. Northeast Organic Farming Association-New York 26th Annual Winter Farming & Gardening Conference, Saratoga Springs, NY (January 25, 2008) – Gallandt.

3.Denmark: a tour of organic farms. Maine Agricultural Trades Show, Maine Organic Farmers and Gardeners Association Day, Augusta, ME (January 15, 2008) ). – Gallandt.

4.Managing the weed seedbank. Organic Agricultural College of Denmark, Rønde (April 11, 2007) – Gallandt..

5.Innovations in physical weed control. Maine Organic Farmers and Gardeners Association and University of Maine Cooperative Extension Service Farmer-to-Farmer Conference, Bethel, ME (November 3, 2007) ). – Gallandt.

6.Diversity and intensity of cover crop systems to manage the weed seed bank and soil health. Maine Organic Farmers and Gardeners Association Spring Growth Conference. Unity, ME (February 25, 2006) ). – Gallandt.

7.Managing the weed seedbank. Northeast Organic Farming Association 31st Annual Summer Conference, Amherst, MA (August 13, 2005) ). – Gallandt.

8.Weed management for organic crop production systems. 2007. Pennsylvania Certified Organic Annual meeting. – Curran.

9.Managing weeds on organic dairy farms. 2008. BMF Dairy Cooperative – Curran.

10.Stump the Weed Guy. Maine Organic Farmers and Gardeners Association Common Ground Country Fair, September 20, 2008 (35 attending) – Gallandt.

11.Ecological weed management. Future Teachers of America program, University of Maine Rogers Farm, Stillwater, ME (June 28, 2005; 18 attending) – Shearin and Gallandt.

12.Threshold-based cover cropping strategies for weed management. University of Maine Rogers Farm Field Day. July 27, 2005 (85 attending) – Gallandt, E.R., C. Reberg-Horton, W.S. Curran, D.A. Mortensen, M.E. Barbercheck and R.J. Hoover.

13.Weed seed predators. University of Maine Rogers Farm Field Day. July 27, 2005 (85 attending) – Shearin, J. A. Shearin, C. Reberg-Horton, and E.R. Gallandt.

14.Stump the Weed Guy. Maine Organic Farmers and Gardeners Association Common Ground Country Fair, September 25, 2005 (30 attending) – Gallandt.

Additional Project Outcomes

Project outcomes:

Impacts of Results/Outcomes

A total of 12 field days were conducted in Maine and Pennsylvania directly reaching about 700 individuals. About 500 farmers directly attended these events. Key impacts from this project identified in a final survey showed that as a result of participating in this project, 41% of the individual were using cover crops for weed suppression, 40% were considering the effects of tillage and mowing for weed suppression, and 15% were considering how to better use seed predators to suppress weeds. Of this same group, 31% had reduced pesticide use, 36% planted cover crops to supplement cash crop fertility, 55% used cover crops to improve the soil, 31% used cover crops to conserve beneficial organisms and 33% used a new cover crop species or mixture as a result of attending the program. Within the group, 40% had reduced the amount of tillage they used as well as reduced fuel use and 31% were trying no-till. A total of 52% had adopted or promoted more sustainable ag practices on their farm or in their work and 88% felt the changes they had made in the last 3 years improved the environment, 57% said it made them more profitable, and 36% thought it provided greater social benefit to their operation or in their work.

Although the activity density experiments focused on only two carabids, the seed predation work showed that numerous organisms likely feed on weed seeds. Seed predation experiments conducted in Pennsylvania showed giant foxtail seed removal (feeding) rates between 40 and 90% over a 14-day period throughout the summer. These experiments clearly showed that a number of organisms consume weed seeds and that it can occur in different cropping systems and during most periods of time during the summer. Both the presence of plant cover and reduced tillage at key periods of time and especially later in summer should help conserve and promote weed seed predators in northeast cropping systems.

From this project, it is clear that organic farmers in particular have an increasing awareness of the “weed seedbank” and the need to consider management of the seedbank in the course of deciding on crop rotation sequences and use of cover crops. This is evident from our survey results and less formally from listening to questions presented by farmers at various grower meetings—questions which often now include some reference to the seedbank. This project has directly contributed to this by supporting a consistent and frequent outreach effort related to these topics. Growers who, several years ago would have listed cover cropping as an important practice for managing weeds now know, through the efforts of this project (and, of course others, e.g., presentations by innovative practitioners of cover cropping for weed management such as Anne and Eric Nordell) that cover crops must be thoughtfully deployed if they are to make significant contributions to weed management efforts.

Economic Analysis

An economic analysis was not conducted as part of this project.

Farmer Adoption

The principles in deploying cover cropping practices to help manage the weed seedbank are essential to the long-term viability of farms where herbicide use is limited, and particularly for organic farmers who rely heavily on cultivation. These farmers share the need for a relatively low seedbank population, and the need to maintain or improve soil quality, which may suffer as a consequence of their reliance on cultivation. Thus, the multiple benefits of cover cropping practices for ecologically-based weed management and soil improvement are fundamental to long-term sustainability of such farms. Our final survey results help show the success of this project in moving farmers closer to sustainability. A total of 52% had adopted or promoted more sustainable ag practices on their farm or in their work during the life of this project and 88% of the respondents felt the changes they had made in the last 3 years improved the environment, 57% said it made them more profitable, and 36% thought it provided greater social benefit to their operation or in their work.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

In the area of cover crops and ecologically based weed management, greater emphasis should be placed on reduced and no-tillage, and especially for organic growers. Cover crop-based, rotational no-till systems in which cash crops are no-till planted into mechanically-killed cover crops can suppress weeds and protect soil quality in organic systems. Systems that explore this on a rotational basis could help build soil quality and reduce energy consumption in organic systems. This is an area that warrants further interest. In the area of weed seed predation, more research is needed to better identify more key players and how we can manipulate cropping systems to take advantage of these conservation biocontrol tools. We are only beginning to understand some of the complex interactions that take place in the field and on field edges and how management influences some of these potential benefits. Collaboration with farmers is key to successful adoption and we encourage NESARE to continue to fund research and educational projects that include complimentary on-farm research.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.