NE1047: Ecological Bases for Weed Management in Sustainable Cropping Systems
(Multistate Research Project)
Status: Inactive/Terminating
Date of Annual Report: 11/26/2013
Report Information
Annual Meeting Dates: 01/03/2012
- 01/03/2012
Period the Report Covers: 10/01/2010 - 09/01/2011
Period the Report Covers: 10/01/2010 - 09/01/2011
Participants
Curran, William (wcurran@psu.edu) - Penn State; Keene, Clair (CLK5285@PSU.EDU) - Penn State; Hahn, Russell (rrh4@cornell.edu) - Cornell; Taylor, Erin (hiller12@msu.edu)- Michigan; Gibson, Kevin (kvngbsn023@gmail.com) - Purdue; Mirsky, Steven (Steven.Mirsky@ARS.USDA.GOV) - USDA-ARS; Chase, Carlene (cachase@ufl.edu)- Florida; Gallandt, Eric(gallandt@maine.edu) - Maine; Servello, Fred (fred.servello@maine.edu)- Maine; Mohler, Charles (clm11@cornell.edu) - Cornell; Smith, Richard (richard.smith@unh.edu) - New Hampshire; Bjorkman, Thomas; (tnb1@cornell.edu) - Cornell; Masiunas, John (masiunas@illinois.edu) - Illinois; Shankle, Mark (shankle@ra.msstate.edu) - MississippiBrief Summary of Minutes
Chair: Eric GallandtMinutes taken by Bill Curran
1) Introductions
After some technical difficulties with the Teleconference system, most everyone introduced themselves and the meeting started about 2:30 pm.
2) Elect Secretary for 2012 (to become Chairperson in 2013)
Curran volunteered for Secretary and took the minutes.
3) Report from Administrative Advisor (Servello)
Fred Servello came on board last year. He has some resources/a person to help us if we need it. Fred mentioned that historically this regional project has struggled a bit, but it also has been productive. Low attendance at the annual meeting has a been a problem. Also, only one year of the last five years report was turned in (NE1026) and we still really need last years report. Our fiscal year is the federal fiscal year (Oct Sep). The fifth (termination) report is the most important, but we should have one report per year. Minutes can serves as the annual report for NE1026. In addition, we also need a substantial annual meeting if possible, more than just a 3-hour meeting. Servello thinks we need a day or more for the meeting. Mohler thinks we need 4-5 hours at least. In addition, we are not really supposed to have the meeting in conjunction with WSSA or the regional meeting. Curran mentioned the difficulty in active participation in this project without any additional funding. This is an unfortunate reality of this type of MultiState project.
4) Future Annual Meeting dates and venues (summer field days at participating Universities; alternate among the regional meetings; desirable "vacation spots" that would encourage participation in the work meetings; other ideas?)
A future date location was discussed. It was decided that it is too difficult to meet as a standalone meeting since we have participants covering such a wide geography. It was agreed that we will meet in conjunction with the WSSA annual meeting in Baltimore in 2013. The WSSA is Feb 4 7 (Mon-Thurs) initial proposed date would be Sunday Feb. 3 in Baltimore or depending on WSSA start time. It was then realized the that Super Bowl was also on Feb 3 and so we tabled this discussion until we confirm WSSA meeting dates and maybe we can meet on Monday or before the Super Bowl on Sunday if necessary.
5) Presentation of Preliminary or Relevant Results and Discussion of 2012 Field Experiments
Objective 1. Cultivation Efficacy - Gallandt discussed some of the details of his work the last summer or two. Much of his work has been looking at efficacy variability with different tools, working rate, of the different tools, etc. Most of these are hand or push tools for smaller vegetable operations. Eric used a theta probe that he thought was pretty good for measuring soil moisture. Eric observed a lot of differences in efficacy due to moisture variation. Gallandt suggests having a core set of data (minimal) and then a more complete set for those that desire to participate more.
PA, DE, and USDA-Beltsville are working with high residue cultivators, but have not yet worked out the details on a common experiment. USDA-Beltsville has been working with Rodale for the last two years. Mohler suggests measuring dry clod size after cultivation helped show that organically managed soil had a finer structure than conventionally mgt. soil. He suggests looking at chain length to estimate soil roughness. Gallandt will send out a template that has the core measurements. Mohler would like to create soils with different tilth e.g. plow wet vs. dry. We would look at cultivation efficacy and hopefully show how tilth and quality influence performance. Bjorkman commented that the most important question is what are conditions when this tool works well or not, and how does the operator influence this and how do you tell a grower what the appropriate tool is for them to use? Gallandt discussed meta data collection. How big should our sample size be? How many quadrats and how big? Intra vs. inter-row collection? Or should we increase our sample size to ensure that we have a minimum number of individuals in our sample size. Eric used Ida gold mustard as a weed surrogate. What could we use as a surrogate weed for no-till? We discussed the resolution power in the weedy control and it was decided that we need to have some minimum number (~50/m2) in the quadrat or have a surrogate. It was suggested that we use both Japanese millet and Ida gold as surrogates to represent a monocot and a dicot.
Some decisions Use chain method for surface roughness, theta probe for soil moisture, bead and string for residue cover at a minimum. Gallandt asked how you can measure the effect of the tool on later weed emergence. It was suggested that discrete tool measurements in isolation from the main experiment might work best. Manipulate the field to create different situations? Mohler has done this to some degree with irrigation.
Objective 2. Weed Seed Maturation
Erin Taylor the AFRI proposal was not successful. MSU will continue to do the project. They have done this for 3 years. Taylor went through the objectives of proposal. Basically it involves four different groups of weeds (flower stalk, capsule or berry, asters, and grasses). Termination included cutting, chopping, or glyphosate. Pick at least 3 species and 3 different control timings flowering, 50% maturity, etc. Mohler commented that more species is the important thing rather than more sites with the same species - 2 to 3 sites per species would be more than enough. Paper recently came out on waterhemp timing of termination and seed production. MSU did 5 species, 3 kill methods and 4 termination times = took two weeks of student labor this winter to process seeds. Could this proposal succeed as a SARE proposal? Other issues; storage of terminated plants bagged vs. basket? Used no- see-um type mesh bags that they sewed themselves. Dont want to favor pathogen activity. MSU included velvetleaf, lambsquarters, Canada thistle and giant foxtail. Eric has some pre-made Japanese tea importer nylon bags that he uses for seed bank work. Mohler said he has better ones and will send around the contact info. Useful common data sheet Erin Taylor will come up with a bare minimum list and send it around.
Objective 3. Amendment Effects on Weed Seed Longevity (Mohler).
Mohler set up this experiment last fall at Cornell with support from the Bellinder, Hahn, DiTommaso and Taylor labs. They collected seed, air dried, threshed, cleaned and counted. Two hundred seeds/bag for BLs and 250 for foxtail. Placed seeds in mesh bags. Went into ground six inches deep in rye, hairy vetch, and no-cover crop treatments. Will mix in cover crops in the spring with seeds placed in the ground last fall, plant to sorghum-sudangrass next summer, and then fall cover crops again in late summer. Spring 2012, spring 2013, and spring 2014 will be harvest dates for seed bags. MSU doing a similar study. Taylor stated that Erin Haramoto who works with Brainard used washers with the bags and will use a metal detector to id and retrieve. MSU is doing this experiment in both field crops and vegetable crops headed by the Brainard and Renner labs. Mirsky has source of stainless steel staples and will send source information around. Chase will not be doing this year, Smith, MSU, and others not clear. If you decide to put in an experiment,email Mohler.
Idea from Curran, maybe we should have a methods discussion? Lots of opportunity to share experience in conducting different kinds of research. This was obvious from our discussion today.
We ended with a discussion about how we can do the tele-conference better next year. We will investigate the use of Adobe Connect, VTC, etc. for the 2013 meeting.
Accomplishments
See objectives 1-3 in the minutesPublications
None to report.Impact Statements
- Improved effectiveness of cultivation for weed management resulting in improved yields, greater harvest efficiency and higher net profits for farmers.
- Improved grower knowledge of how and when to remove weeds before they set seeds with consequent reductions in weed seed banks leading to better yields, reduced costs for weed management and higher net profits for farmers.
- A new method for reducing the density of weed seeds in the seed bank leading to better yields, reduced costs for weed management and higher net profits for farmers.
Date of Annual Report: 11/26/2013
Report Information
Annual Meeting Dates: 02/03/2013
- 02/03/2013
Period the Report Covers: 10/01/2011 - 09/01/2012
Period the Report Covers: 10/01/2011 - 09/01/2012
Participants
Curran, William (wcurran@psu.edu) - Penn State; Keene, Clair (CLK5285@PSU.EDU) - Penn State; Hahn, Russell (rrh4@cornell.edu) - Cornell; Bellinder, Robin (rrb3@cornell.edu) - Cornell, Bhashar, Vinay (vb259@cornell.edu) - Cornell; Renner, Karen (renner@msu.edu)- Michigan; Haramoto, Erin (haramoto@msu.edu) - Michigan; Taylor, Erin (hiller12@msu.edu)- Michigan; Gibson, Kevin (kvngbsn023@gmail.com) - Purdue; Mirsky, Steven (Steven.Mirsky@ARS.USDA.GOV) - USDA-ARS; Chase, Carlene (cachase@ufl.edu)- Florida; Gallandt, Eric(gallandt@maine.edu) - Maine; Servello, Fred (fred.servello@maine.edu)- Maine; Mohler, Charles (clm11@cornell.edu) - Cornell; VanGessel, Mark (mjv@UDel.Edu) - Delaware; Smith, Richard (richard.smith@unh.edu) - New Hampshire; Taylor, Alan (agt1@cornell.edu) - Cornell; Bjorkman, Thomas; (tnb1@cornell.edu) - CornellBrief Summary of Minutes
Election of Chair for 2013 Kevin Gibson is Chair for next year. Karen Renner is taking minutes today.Report from Administrative Advisor (Fred Servello): Fred thanked Bill for all of his efforts in organizing the meeting. The registration system took care of minimal expenses of the meeting. The communication system will be reviewed. Power points were submitted ahead of time that spurs the annual report getting completed. These power point presentations were sent to all NE participants to keep in a folder as a reference. The annual report for 2012 must include: 1) minutes from the 2013 meeting Karen will send to Bill 2) accomplishments of the 2012 fiscal year (narrative of accomplishments given by each state). Send your states narrative to Bill Curran in the next 30 days so he can compile and send our report in.
Selection of 2014 meeting date and location; Discussion of Philadelphia NE meeting next year the first week of January (dates not known by the group) or WSSA at Vancouver February 3-6. Chuck would like a longer meeting after the WSSA meeting ends. Meeting will be in Vancouver.
Presentations of 2012 Results and Discussion:
Objective 1: Determine how soil conditions affect efficacy and selectivity of cultivation implements for the control of various weed species. Two states are participating in this objective: Maine and Pennsylvania. The soil conditions variable differs between the two studies.
Gallandt Univ. of Maine. They are trying to determine why there is a high level of variability in mechanical weed control efficacy in farm fields. Is the variability in efficacy a function of environmental factors? Example: as you increase soil moisture do you decrease cultivation efficacy (slide 2). They seeded a surrogate weed and had 70 sample locations. They had two quadrants (wheel track side and non-wheel track side) per sample site. Soil moisture, texture, density, roughness, wheel track were the variables. Most disappointing data set Eric has ever collected . None of the statistics produced any significance in the data set. The explanatory variables had a lot of variability (moisture from 6 32%, texture from sand to clay loam). Average control by cultivation was 67%. Chuck commented that most of the data is in the middle of the histogram so not enough data in the tails. Next year suggestions: two cultivation tools and make a comparison. Two speeds and make a comparison. Two types of tines on a tine weeder would be interesting or a tine weeder and a rotary hoe. The goal is 67% across the whole field. The tail with poor control is of interest. Why do you have this tail? Maybe next year keep the in-row weed data separate (divide the quadrat into 3 sections). Maybe the tails are poor soil flow into the rows so the weeds are not being buried. Maybe next year not measure outside the row just focus in the row since it appears that wheel tracks didnt make a difference.
Maybe you should grid sample to develop variable zones and then cultivate across the system and see the variability based on EC, pH, SOM (use Veris MPX), N, P, K. Weed populations and safe sites are based on management practices that overrun inherent natural features of the field (slope, soil type). Grid sampling and developing VR zones will allow us to measure weed emergence and cultivation efficacy based on VR (KAR comment)
Bill Curran/Clair Penn State. High residue cultivator w/ 20 sweeps: John Deere 886. Two experiments: Rye (soybean) and hairy vetch (corn). Measured inter-row weed density. Had various cultivated treatments including one, two, or three cultivations w/ various timings. In 2011 soybean yields were greater in plots that had multiple cultivations. Rye mulch increased soybean yield (there was dry weather in 2011 so rye mulch improved soil moisture). Surrogate weed Ida gold mustard didnt work in no-till (poor emergence). In 2012 there was a benefit of three cultivations compared to two. There were more weeds in the rye in 2012 possibly because these plots had moisture so more weed emergence. There was poorer crop emergence in the rye mulched areas. Corn/vetch plots in 2012: needed more than one cultivation for weed control and mulch increased yield by 13 bushel. Soil moisture was also measured in soybean in 2012. Rye did not interfere with cultivation. PA will repeat the experiments in 2013. Pigweed is very sensitive to mulches so would not suggest seeding only this species. Residue stays fairly intact for treatments that are cultivated once. Corn data is analogous to Jane Mt. Pleasants work in a tilled system in the 1990s.
Objective 2. Determine the reproductive growth stage at which summer annual weeds can be terminated and still produce viable seeds and quantify the effect of method of life-termination on seed production.
Combined Locations: presented by Erin Taylor: 5 sites across states. Univ. of Ill will repeat the flowering timing in 2013. In 2012 they had no viable seeds produced when terminated at flowering time. Cornell had 3 species and all three kill methods. Cornell did a detailed greenhouse study and then did the summer study. Farnaz did this research and is presenting a talk at WSSA. Their work included 4 different stages of development based on appearance of capsule color on velvetleaf (yellow, yellow/green, dark green, black); Lambsquarters: 3 43 days after flowering and had 5 stages of development that were harvested; giant foxtail: 5 stages also 0 20 days after flowering. For velvetleaf when seeds are fresh they are viable; the faster rate of drying decreased viability for velvetleaf. For lambsquarters, plants that were cut and left (if inflorescence or whole plant cut) seeds were produced by13 days; this is in contrast w/ velvetleaf. Lambsquarters still produce viable seed when cut and laid in the field. They have data on black and brown seeds also that are not presented. The brown seeds have an undeveloped embryo and are not viable. The data presented is only the black seeds. For giant foxtail: the foxtail seeds lose viability when they dry (similar to velvetleaf). So a farmer should remove giant foxtail and common lambsquarters at the time of flowering by either kill method. Chopping velvetleaf reduced seed viability and velvetleaf has a longer time after first flowers are produced to remove from the field. Cornell also completed common ragweed and wild proso millet. Maine researched hairy galinsoga, crabgrass, and redroot pigweed. At the time of flowering, either cut or chop had a few seeds produced (none w/ glyphosate). Galinsoga is indeterminate so maybe at flowering there might have been a few formed seeds at flowering. Delaware had three kill methods, 3 timings, and 3 weed species. Jimsonweed 10 to 14 days between flowering and brown seed stage. Jimsonweed did not produce seed at the flowering stage. By brown seed set, viable seed was produced (10- 14 days after flowering). There were fewer viable seeds produced with glyphosate compared to the chop or cut method. For foxtail, at flowering data was similar to Farnezs data that viable seed was produced. Lambsquarters was difficult to differentiate flowering from immature seed. Michigan 2nd year of data. MI is the only site with seeds out overwintering for the second year. There was 2-3 weeks from flowering until maturity with jimsonweed. Foxtail seed flowering was still in the whorl, immature was still only green seed, mature was when 50% of the seeds were brown (this may differ by university on classifying immature and mature). Jimsonweed and velvetleaf: 90% more seed produced in mature capsules, compared to immature capsules.
Ideas: Determinate plants flowering based on day length so could we use this. Could GDD since emergence be used, or biomass or other variables be used as guidelines? We would like to give growers additional guidelines for removing weeds.
Objective 3 results - Determine the extent to which soil amendments such as green manures and compost affect seed mortality of various weed species.
Chuck Mohler there was no difference in seed survival over winter because of the cover crop species. They had over 50% overwinter survival of the seed.
Alan Taylor and Sarah Pollicove seed germination and viability testing developed for four weed species to have optimum percent germination without using PGRs or other chemicals to break dormancy. Then use TZ for tetrazolium test for small species and larger seed break physical dormancy. Velvetleaf: 35C 16/8 light/dark = 85% and then pierce seed by hilum to break physical dormancy; giant foxtail 20/30 and 16/8 light dark = 60% germ and then TZ test but staining should be throughout the embryo (see images from A. Taylor); lambsquarters same as giant foxtail = 64% and then TZ test and watch for lack of uniform staining (also the green and turgid embryo even though it doesnt stain is considered viable); Powell amaranth 20/35 with 10/14 dark/light 76% germination.
Thomas Bjorkman buried seed bags 4 deep. There is no sand in their bags. They were buried in late June and pulled out in August. A cover crop was incorporated and then a new set of seed bags were placed into the soil. Sudangrass and buckwheat were the two cover crops. They are seeing a high level of fatal germination (sprouting) in their studies with giant foxtail. Powell amaranth had only a few sprouted seeds, and fewer sprouting after buckwheat.
Erin Haramoto (Dan Brainard) Michigan the experiment is in SW MI on sandy soil with Powell amaranth and large crabgrass are the two species and the covers are rye, rye + vetch, and no cover. Dry residues are added to the bags and not green covers like other researchers. Seed bags are buried into growing cover crops in November and are removed in June. Some of the bags were mixed with dry cover crop residues and returned to the soil and reburied until August. Seeds are not analyzed for dormancy but just for viability. All seed that was TZ tested was dead. Powell amaranth 70% viable after being buried for 6 months; large crabgrass had only 19% viability. There was a trend for greater seed viability where there were cover crops. There was not a moisture difference, not a moderating temperature difference with cover/no cover. Microbial community in the seed bags are changing the microbial community in the bag.
Mark Shankle Mississippi has a burial study also.
Kevin Gibson Purdue buried bags this year (following Chucks protocol).
Erin Taylor (Karen Renner) have the experiment ongoing in the field also with three species and clover, rye, and no cover. They will have viability data only.
Other business
5:30 PM - Adjourn
Accomplishments
Outcomes: This was the first official year of the project, so outcomes are yet to be determined.<br /> <br /> Outputs:<br /> Penn State - In 2011, control was similar and 90% or better for treatments cultivated either 2 or 3 times. The single cultivation treatments had the lowest level of weed control and especially 4 weeks after planting providing less than 50% control. There was no difference in cultivation efficacy between the cover crop and no cover crop plots. There was no evidence of soybean stand reduction with cultivation timing or frequency. Soybean yield did differ with cultivation treatment and cover crop residue. In general, soybean no-tilled into a rye cover crop yielded more than the no cover crop treatments. Although not always significant, plots cultivated twice or three times tended to have higher yields than plots with single or no cultivation. In the future, closer monitoring of soybean stand, soil moisture, and weed-free controls will be included in these experiments.<br /> <br /> Michigan State (Renner et al.) - Multiple weed management strategies directed at seeds and weed seedlings improve weed control in organic and sustainable systems as compared to a single tactic, thereby improving food production, quality and net return to farmers. There are three objectives in this new multi-state project and we are involved with two of these objectives (2 and 3). They are: Objective 2) to determine the reproductive growth stage at which summer annual weeds can be terminated and still produce viable seeds and quantify the effect of method of life-termination on seed production, and 3) to determine the extent to which soil amendments such as green manures and compost affect seed mortality of various weed species. Understanding how production of viable seeds relates to the point in the life-cycle at which a weed is killed and the method by which it is killed will improve preventive weed management. Improved understanding of how organic matter amendments, including green manures and compost, affect seed survival following initial seed rain will allow growers to implement cropping systems that reduce weed seed banks and thus weed pressure in subsequent crops. <br /> <br /> For Objective 2, weeds were terminated at the early floral stages, when immature seed was present, and again at 50% maturity by pulling, chopping, or herbicide application. Plants were stored in bags in the field between crop rows until early November at which time the bags were retrieved and the weed seed tested for viability and dormancy. Our site has collected 2 years of data for our 5 weed species (common lambsquarters, giant foxtail, jimsonweed, velvetleaf, and Canada thistle). For all species, termination at the time of the first open flower did not result in viable seed production for any termination method. Terminating weeds with immature seeds reduced seed bank inputs compared to allowing seeds to mature. The best termination method to use appears to be species dependent. <br /> <br /> For Objective 3, 200 weed seeds (velvetleaf, common lambsquarters, and giant foxtail) were overwintered in mesh bags filled with 100 g of sand, buried to 15 cm. Bags were buried in cover crop plots with actively growing rye Wheeler, medium red clover Marathon, or no cover. There were 4 replications. Bags were exhumed prior to cover crop incorporation with a chisel plow. One set of bags was set aside to access overwinter survival. The other 5 sets of bags were re-bagged with a fixed amount of cover crop added from the respective plot. Due to the mechanical preparation of the field prior to organic dry bean planting, the new bags were stored buried 15cm deep in a no cover area of the field for a couple of weeks and placed back into the cover crop plots (again 15 cm deep) after dry bean planting. Pull times for our study were more frequent than those of the regional group. We pulled bags at 1, 2, 4, and 6 months after cover crop incorporation and have a final set ready to be pulled at 12 months after incorporation (next June). The seed bags retrieved thus far have been sieveds, counted, and tested for germination. We are currently conducting the final viability tests using tetrazolium chloride. <br /> <br /> (Brainard et al.) As expected, over-winter survival did not differ among treatments for any species, although high variability limited our ability to detect small differences. Overall, 70% of A. powellii seeds survived overwinter, and 19% of D. sanguinalis seeds survived. <br /> <br /> Cornell (Mohler et al.) - For objective 2, Results of greenhouse study<br /> Velvetleaf seeds began becoming viable during the second development stage stage (7-13 DAF), and reached 100% viability during the third stage (14-16 DAF). The rate at which full viability was approached differed significantly among treatments. In common lambsquarters, black-colored seeds were viable and poorly developed brown-colored seeds were not viable. This species did not produce seed at 3 DAF and seeds from 13 DAF had lower viability than later stages of development. <br /> <br /> For objective 3, As expected, over-winter survival did not differ among treatments for any species. For all species sufficient seeds remained in the spring to provide an adequate test of whether the incorporation of cover crop material affects seed survival.<br /> <br /> Maine - For objective 1, efficacy ranged from 6.7 to 100%, with mean and median values of 67 and 68%, respectively. Contrary to expectations, soil conditions failed to explain any portion of the considerable variation in efficacy. Mustard mortality was similar with or without tractor wheel traffic (P = 0.6708). Likewise, bivariate fits of mustard mortality with percent sand, bulk density, soil moisture, or surface roughness failed to detect any relationships between our dependent and explanatory variables.<br /> <br /> It was surprising that the large amount of variability in efficacy was not related to measured soil conditions, despite relatively large ranges in these explanatory variables. Sand, for example, ranged from 2 to 90%; bulk density ranged from 0.64 to 1.27 g cc-1; soil moisture ranged from 10 to 32%; and surface roughness from 62 to 90 on a relative scale.<br /> <br /> For objective 2, seed was not recovered from the glyphosate treated plants; often the plants as decomposed and were not recognizable, presumably due to the small size at the time of application, and the duration they remained in the field (Table 1). Cutting and chopping prevented viable seed production in both A. retroflexus, and D. sanguinalis. <br /> <br /> Two cut and two chopped H. galinsoga plants produced viable seeds (9 viable seeds for each treatment). Although we attempted to impose our treatments at the first appearance of an open flower, it is possible that our study plants had flowers that were more mature than this. H. galinsoga is day-neutral with regard to flowering, with each lateral branch terminating in a flower head (Warwick and Sweet, 1983). Viable seeds are formed as early as two weeks after flowering (Ivany and Sweet, 1973). <br /> <br /> Activities: <br /> <br /> Penn State - We are participating in the first objective of a three objective regional project (NE-1047). This objective is to determine how soil conditions affect efficacy and selectivity of cultivation implements for the control of various weed species. In PA, we are specifically evaluating the effectiveness of shallow high residue cultivation in no-till soybean and corn. In 2011, we conducted an experiment in central Pennsylvania in soybean and in both soybean and corn in 2012. Cash crops were no-till planted in 76-cm rows with banded herbicide application at planting. The main plot was cultivation treatment and a split plot was cover crop residue (cereal rye) vs. no cover crop residue. Data collection included crop stand count, weed density, late summer weed biomass, and crop grain yield. Cultivation treatments included once at 4, 5, or 6 weeks after planting, cultivation twice at 4 and 5, 4 and 6, or 5 and 6 weeks, and cultivation three times at 4, 5, and 6 weeks after soybean planting. Data for 2012 is still being processed. <br /> <br /> Michigan (Renner et al.) - Objective 2: We will choose one weed from each of group A (small seeded broadleaves), B (velvetleaf), C (Canada thistle) and D (grasses). Plants from each species will be terminated at the early floral stage for Groups A, B, and C or at the first appearance of the green seed head for Group D. Additional plants will be terminated when immature seed is present and again at 50% seed maturity. Collection times are based on the most advanced stage on a given plant. Three methods of termination will allow us to determine how method and timing of termination influence viable seed production. The termination methods are: pulling the plant (simulating hand pulling or hoeing), clipping/chopping (simulating mowing), applying the herbicide glyphosate. Each plant or collection of reproductive structures from a plant will be stored separately in a nylon-mesh residue bags or baskets. In early November of each year, the baskets and residue bags will be retrieved from the field, and seed production determined for each sample. Some seeds will be immediately tested for viability, while other seeds will be returned to the field surface and tested for viability in the spring. For each weed species, viability and germination will be analyzed using ANOVA in SAS to determine if termination methods and timings differ. <br /> <br /> Objective 3: Seeds of two or more weed species collected from local populations will be buried in fine mesh packets in each plot late in the fall of year 0 while cover crops are growing, but before any cover crop residue or other amendment has been incorporated. Each packet will contain several hundred seeds mixed with 100 g of fine sand and initially no amendment. Amendments will include a control treatment that receives no amendment, at least one legume cover crop, and at least one small grain cover crop. Cover crops will be planted at the appropriate time for each location. Packets will be buried at 15 cm, and enough packets buried to allow removal of one packet from each replication in each of the following two or more springs. Each spring before incorporation of cover crops and other amendments, all packets will be removed from the soil. One set will be set aside for analysis of surviving seeds. The other packets will be weighed, the sand and seeds mixed with amendment at a rate corresponding to the rate incorporated in the field plots, and the sand and seeds will then be returned to a packet, and reburied in the plot from which they came. The same crop or summer cover crop will be grown on all plots during the summer. To assess the number of seeds remaining in a packet, the sand-seed-residue mix will be spread shallowly in a dish, and partially decomposed seeds and empty seed coats will be destroyed when screening out the sand. The seeds will be counted and viability assessed by light pressure. Differences in seed survival between amendment treatments, burial periods and species will be assessed initially at the state level by time-series ANOVA of arcsine square root transformed seed survival proportions. <br /> <br /> Michigan (Brainard et al.) - Overwinter survival of buried weed seeds (Amaranthus powellii and Digitaria sanguinalis) was evaluated in a long-term trial examining the effects of cover crops (none, rye or rye-vetch) and tillage (moldboard plow vs strip-till) on weeds in a three-year vegetable crop rotation (sweet corn: snap beans: winter squash). Cover crop and tillage treatments have been imposed in the same plots since 2009. Seeds were buried following winter squash harvest in fall 2011, exhumed in spring 2012, and tested for viability. Sufficient additional bags have been buried to examine survival for 3 additional years.<br /> <br /> Initial Burial. Mesh bags (approx. 8 x 10 cm) were constructed from no see-um mesh (Outdoor Wilderness Fabrics) using nylon thread. Bags were filled with 100 g of sand that had been sieved through a 500 µ sieve (smaller fraction kept) mixed with 100 seeds of A. powellii or 200 seeds of D. sanguinalis. Bags were buried 15 cm deep in all 6 cover crop x tillage combinations, on 9 November 2011. Cover crops had already been established (10 September 2011)rye was seeded at 112 lbs/acre in rye only plots and at 56 lbs/acre in the rye/vetch plots with vetch at 20 lbs/acre. The field was disked prior to cover crop planting; no other weed management was used in the fall. <br /> Exhumation and viability testing. One bag of each species from each plot was exhumed on 4 June and stored until viability testing. Seeds were removed from bags by sieving through a 500 µ sieve. Seeds of A. powellii were then germinated at 30°C with 2 µM GA. Seeds of D. sanguinalis were germinated in deionized water at 30°C. Ungerminated seeds were assessed for viability by a combination of squeeze testing and TZ testing.<br /> <br /> Reburial. In moldboard plow treatments, all remaining bags were pulled prior to spring tillage, filled with a fixed amount of cover crop residue, and re-buried following tillage and planting the next day. Bags were filled with rye and vetch residue that had been collected prior to termination (9 May 2012), dried down, and coarsely ground in a Wiley mill. Pieces of ground residues were approximately 5-10 mm long. Experiment-wide, dry rye biomass averaged 6350 kg/ha in rye only plots and 6460 kg/ha with 1100 kg/ha vetch biomass in rye/vetch plots. For rye plots, we added 0.3 g of dry rye residue per bag; for rye and vetch plots we added 0.3 g dry rye and 0.05 g dry vetch residue. <br /> <br /> Cornell - For objective 2, three common summer annual weed species: velvetleaf, common lambsquarters, and giant foxtail were grown in a greenhouse greenhouse. The flowering phenology of each plant was recorded throughout the experiment, and individual capsules of velvetleaf tagged with flowering date. The experiment had three treatments: (a) plant cut at base and left to dry for 4 wk on the greenhouse bench, (b) individual capsules (velvetleaf), terminal infolorescence (common lambsquarters) or first seed head (giant foxtail) were cut from the plant and left to dry in the greenhouse for 4 wk, and (c) reproductive material removed from the plant and seeds evaluated immediately. Velvetleaf plants were harvested when two or more capsules were fully mature and capsule were classified into four developmental stages based on color.. Common lambsquarters and giant foxtail were harvested at 5 developmental stages based on days after flowering (DAF). Seeds were tested for germination and viability of non-germinable seeds assessed by piercing velvetleaf and staining giant foxtail and common lambsquarters with tetrazolium chloride. . This experiment was repeated in the field during the 2012 growing season but results are not yet available. Additional experiments were conducted on velvetleaf, common lambsquarters, giant foxtail, wild proso millet and common ragweed during the 2012 growing season following the standard Obj. 2 protocols. Treatments were (1) plants pulled, (2) plants chopped, and (3) plants painted with glyphosate. Plants were harvested (1) shortly after flowering, (2) at milk stage and (3)when mature seeds first appeared. Plants weere left in the field in mesh bags until November.<br /> <br /> For objective 3, Cover crop treatments of grain rye, hairy vetch and bare control were planted 11 Sep 2011 ina replicated block design with five replications. Plots were 20 x 45. Seeds of velvetleaf (200), common lambsquarters (200), Powell amaranth (200) and giant foxtail (250) were placed in 83 g of sand in 3 x 4 organza mesh bags and individually buried at the bottom of a 7 hole made with a bulb planter. This put the center of the bag at about 6 depth. On 17 May bags were dug up, brushed off, opened and material dumped into a pan. One set of samples were retained for analysis. These were placed in 6 pie pans and dried at 40 C in a forced draft oven for 24 hr to prevent seed germination. If originating from a cover crop plot, chopped cover crop material was mixed with the sand and seds of the remaining samples. Cover crop material was added at a rate equivalent to 600 g/m2 (calculation assumed a 2,000,00 lb/A furrow slice of 6 depth). The sand mix was replaced into new mesh bags and double baged to avoid rupturing bags during recovery. Plots were mowed, disked and then rototilled the same day. Samples destined for reburial were held in ice chests before and after opening. Bags were tied to three washers for 1 bolts and bags plus washers were reburied as before on 18 May 2012.<br /> <br /> Maine - For objective 1, the University of Maine research group conducted a single field experiment related to Objective 1 in 2012. Cultivation efficacy and soil conditions were measured at 70 locations, randomly selected along five corn row transects in a 2 ha field of silage corn. The cultivator was a common, older model, 3-point-hitch-mounted, 4-row Case International Model 183 with Danish s-tines and 10 cm sweeps and gage wheels. Condiment mustard, Idagold, (Sinapis alba) was used as a surrogate weed. On June 20, 2012 (corn 10 cm tall, 2-leaf stage), Idagold was sown over the top of the corn at 5.5 kg ha-1 using an air seeder with 15 cm row spacing. Due to wheel tracks in this four-row system, our study rows were not in a uniform soil environment: wheel-tracked sides of the rows were more compact than areas lacking wheel traffic. Thus, paired samples were taken at each of 70 locations for a total of 140 samples. Soil surface roughness was measured on July 1; samples to measure bulk density and texture were collected on July 1-2. Soil moisture was measured, and pre-cultivation censuses performed on July 3, and the field was cultivated (mustard at 1-leaf stage); post-cultivation censuses were performed on July 5.<br /> <br /> For objective 2, the University of Maine research group tested cutting, chopping and glyphosate application effects on seed maturation in Galinsoga cilata, Amaranthus retroflexus, and Digitaria sanguinalis. Treatments were imposed on August 28-30, 2012; plants were collected from the field on November 7, 2012.<br /> <br /> Milestones: (year 1)<br /> <br /> Objective 1. Plant cover crops in fall. Till ground or roller-crimp cover crops and plant crops. Measure soil properties, count weeds in quadrats, assess crop stand; cultivate; count weeds in quadrats and assess crop stand after cultivation. Repeat for additional cultivations.<br /> <br /> Objective 2. Determine which labs will study which species. Plant crops and weeds in spring. Terminate sample plants at various phenological stages and confine plants in mesh to capture seeds as they mature. <br /> <br /> Objective 3. Plant cover crops, gather seeds, and bury seed packets in the fall. Run tests of initial seed viability. Recover seed packets in the spring, till plots, mix amendments into packets, rebury most packets. Assess seed viability in spring sample packets. Plant and maintain crops or cover crops over the summer and remove crops in the fall in time for cover crop planting. Collect and analyze Study B rapid assessment packet at 3 month intervals.<br /> <br />Publications
Keene, C.L. and W.S. Curran. 2012. Effectiveness of shallow high residue cultivation in no-till soybean. Proc. Northeast Weed Sci. Soc. 66.<br /> <br /> Taylor, E., K. Renner, and C. Sprague. 2012. Reproductive potential of summer annual weeds based on termination method and timing. North Central Weed Science Society annual meeting. 71. St. Louis, MO. Poster.Impact Statements
- Improved effectiveness of cultivation for weed management resulting in improved yields, greater harvest efficiency and higher net profits for farmers.
- Improved grower knowledge of how and when to remove weeds before they set seeds with consequent reductions in weed seed banks leading to better yields, reduced costs for weed management and higher net profits for farmers.
- A new method for reducing the density of weed seeds in the seed bank leading to better yields, reduced costs for weed management and higher net profits for farmers.
Date of Annual Report: 02/02/2015
Report Information
Annual Meeting Dates: 03/07/2014
- 03/07/2014
Period the Report Covers: 10/01/2013 - 09/01/2014
Period the Report Covers: 10/01/2013 - 09/01/2014
Participants
A series of online meetings were held. Participants at those meetings includedCarlene Chase, U. Florida
Bill Curran, Pennsylvania State University
Kevin Gibson, Purdue University
Steve Mirsky, USDA, ARS, ANRI
Karen Renner, Erin Haramoto, Erin Taylor, Dan Brainard, Michigan State University
Eric Gallandt, U. Maine
Fred Servello, U. Maine, Advis/Admin
Mark VanGessel, U. Delaware,
Alan Taylor, Thomas Bjorkman, Charles Mohler, Russell Hahn, Robin Bellinder - Cornell
Brief Summary of Minutes
Minutes: 2014 MeetingA series of online meetings were held in 2014 using Adobe Connect. The following primarily summarizes the final Adobe Connect meeting, which was held to discuss the 2015 meeting and select a new Chair.
Election of Chair for 2014-15 – Karen Renner agreed to serve as Chair for the next year.
2015 meeting information: the meeting will coincide with the 2015 Weed Science Society of America (WSSA) annual national conference in Lexington, KY. Suggestions for the meeting are as follows:
1. Start in the morning on the day WSSA starts (Monday) and conclude approximately 2 hours after lunch. Karen Renner will chair the meeting and Erin Hill will take notes.
2. Determine the need for a conference call to accompany the in-person meeting once attendance at WSSA is known.
3. Have everyone bring a list of presentations/abstracts and a separate list of publications from 2011 (beginning in October) through 2015.
4. Assign individuals to summarize Objectives 1 and 2 for the meeting. Gallandt and Curran summarize Objective 1. VanGessel and Renner summarize Objective 2 to date. Mohler report on their research from Obj. 2 for 2014.
5. Discuss Objective 3 data: Michigan, Cornell, others. Discuss what to do with the research data. Assign individual(s) to be lead author on the paper.
6. Discuss the direction of future research by this group. This work terminates September 2016 but we will have our objectives completed one year early. We can have the report written and hold until presentations/publications are completed in late 2015 and 2016 and then submit.
7. Consider asking the NC-1191 chairperson and secretary to the meeting to discuss the direction of that group which is on the same timeline for a proposal termination and new pre-proposal that we are. They may be meeting at WSSA (however they often meet in the summer). Their title is “Weeds as Phytometers in Changing Environments” (previously this group was NC-1026 Weed Population Dynamics for long term decision making… (or something like that).
OTHER NOTES:
Objective 1 (effect of soil conditions and cultivation implements on weed control): Two states participated in this objective: Maine and Pennsylvania. Since only two states participated and followed different protocols, this objective was not discussed during our meetings.
The researchers involved in Objective 2 (the effect of termination of seed production/viability) agreed to share results to present a poster at the 2015 WSSA meeting. Mark VanGessel agreed to lead this effort. The Michigan and Delaware research teams used similar methods and species and will work together to develop a paper. Michigan (Karen and Erin) will take the lead in developing that paper. The Cornell and U. Maine teams u used different species and are at different stages in their work so they will decide on how they want to proceed with field research and in developing an additional paper or papers.
Objective 3 (effect of soil amendments on seed mortality). Research is ongoing and will be discussed during the 2015 meeting. Methods vary among the research teams so a conversation should occur to clarify if a group paper will be developed.
There was a suggestion to focus the pre-proposal on the Northeast and weeds unique to the Northeast cropping systems. Currently participation includes IN, MI, IL and KY (Erin Haramoto will be an Assistant Professor there in August).
Several participants noted that soil amendments appear to have little or no effect on weed seed mortality. They suggested that if our data shows this there is no reason to continue further along the lines of Objective 3. Renner suggested having multi-state, multi – locations on organic grower farms burying seeds into amended systems and seeing the short-term effect (1-9 months after burial) on seed mortality. This may be of interest if we find a weed species or an amendment that influences seed mortality.
There was a discussion on including a soil biologist if we further pursue Objective 3 (and seed scientists) to determine how amendments influence seed mortality.
Accomplishments
2014 NE-1047 Report<br /> Overview: We proposed a five year project (October 2011 to September 2016) that would 1) determine how soil conditions affect efficacy and selectivity of cultivation implements for the control of various weed species, 2) determine the reproductive growth stage at which summer annual weeds can be terminated and still produce viable seeds and quantify the effect of method of life-termination on seed production, and 3) determine the extent to which soil amendments such as green manures and compost affect seed mortality of various weed species. Although several investigators will continue to work individually on these objectives, multistate experiments following the same protocols are complete or will be completed in 2014 or by early 2015. A review of work conducted in 2014-15 is needed, primarily on the third objective, but the annual meeting in 2015 will focus on whether there is interest in continuing/renewing the project around the current objectives or developing a new line of research. Reports for 2013-14 were submitted by individual research teams, condensed, and are presented below. <br /> <br /> Objective 1: Determine how soil conditions affect efficacy and selectivity of cultivation implements for the control of various weed species. Two states participated in this objective: Maine and Pennsylvania. Since only two states participated and followed different protocols, this objective was not discussed during our meetings. The University of Maine research group conducted two field experiments related to Objective 1 in 2013. Cultivation efficacy and soil conditions were measured at 70 locations, randomly selected along five corn-row transects in a 2 ha field of silage corn. The cultivator was a common, older model, 3-point-hitch-mounted, 4-row Case International Model 183 with Danish s-tines and 10 cm sweeps and gage wheels. Condiment mustard, ‘Idagold,’ (Sinapis alba) was used as a surrogate weed. On June 11, 2013 (corn 10 cm tall, 2-leaf stage), Idagold was sown over the top of the corn at 5.5 kg ha-1 using a spin-spreader. Soil surface roughness was measured on June 26; samples to measure bulk density and texture were collected on June 26-27; soil moisture was measured on June 27. Pre-cultivation censuses performed on June 27, and the field was cultivated (mustard at 1- to 2-leaf stage); post-cultivation censuses were performed on June 29. Efficacy ranged from 5.8 to 100%, with mean and median values identical at 56%. This is 10% lower than efficacy in 2012 (mean and median efficacy in 2012 were 67 and 68%, respectively). Consistent with results from 2012, and contrary to expectations, soil conditions failed to explain any portion of the considerable variation in efficacy. Bivariate fits of mustard mortality with moisture, bulk density, soil moisture, surface roughness or texture failed to detect any relationships between our dependent and explanatory variables. It was surprising that the large amount of variability in efficacy was not related to measured soil conditions, despite relatively large ranges in these explanatory variables. Bulk density, for example, ranged from 0.7 to 1.47 g cc-1; soil moisture ranged from 20 to 37%; and surface roughness from 78 to 90 on a relative scale. Each census location was geo-referenced, and dependent as well as explanatory variables were subject to correlogram analysis to determine the effects of space. Correlation of mortality among census locations was generally low and consistent over the 80-meter distance range studied in this experiment. Soil parameters including surface roughness, bulk density and moisture likewise did not show a strong spatial signature for correlation over this scale (data not shown). Texture components, sand, silt and clay proportions, were, not surprisingly, negatively correlated among samples separated by 70 meters, but exhibited generally weak correlations at closer distances (data not shown). Completing two field seasons of research focused on site conditions, and having failed to detect any strong explanatory evidence from soil parameters studied, we aim to conclude this line of investigation and publish our results to date. In a separate field experiment condiment mustard was sown on four occasions, approximately at 3-day intervals, to establish a greater diversity in seedling size at the time of cultivation. Efficacy averaged 84%. As expected, efficacy was greatest for 1- and 2-leaf weeds (91 and 88%, respectively), intermediate for 3-leaf weeds (81%), and lowest for 4-leaf weeds (70%). This field experiment will be repeated in 2014, with the addition of several other surrogate weed species to initiate research on species-specific effects on efficacy variation. Specifically, we aim to examine two broadleaf and two grass species varying in seed mass and early seedling root:shoot allocation.<br /> <br /> Objective 2. Determine the reproductive growth stage at which summer annual weeds can be terminated and still produce viable seeds and quantify the effect of method of life-termination on seed production. Cornell University: Lambsquarters and giant foxtail were grown in soybeans summer of 2012 and killed at anthesis, when the first small green seeds formed or when the first black (LQ) or brown (GF) seeds formed. Plants were killed by chopping them into amall pieces, uprooting the plant or wiping the plant with glyphosate. Plants were placed in mesh bags to prevent loss of seeds and laid on the ground (chopped, uprooted) or left upright (glyphosate). Plants terminated at anthesis produced no or very few viable seeds. GF plants terminated at the first brown seed stage averaged about 4,000 viable seeds each and LQ plants averaged abut 2,000 each. Plants of GF terminated at the first green seed stage averaged over 400 seeds per plant when terminated with glyphosate but fewer than 10 if terminated by uprooting or chopping. LQ plants terminated at the first green seed stage averaged about 200 seeds regardless of treatment. Michigan State: Five summer annual species were terminated at three times (flowering, presence of immature seed, presence of mature seed) using three termination methods (cut at plant base, chopped into 10 cm sections, glyphosate). This project was conducted for two summers (2011 and 2012) with six replications each summer at the MSU Agronomy Farm in East Lansing, MI. At the time of termination plants were placed in mesh bags and either stored lying between soybean rows (cut and chopped samples) or left standing (glyphosate samples). All bags were retrieved in November of each year, at which time the viability of seeds recovered was determined using a combination of germination and tetrazolium testing. A subset of seed were returned to the field and retrieved again in March to determine the impact of overwintering on seed viability. Overall this study demonstrated that controlling escaped weeds during flowering is the best strategy for preventing additions to the seed bank. Canada thistle produced few viable seeds in both years of this study. Common lambsquarters, giant foxtail, jimsonweed*, and velvetleaf produced an average of 9,500, 390, 2,800*, and 370 seeds/plant when allowed to mature in corn and soybean fields. Controlling weeds when seeds were still immature reduced seed bank inputs by 80% or more compared to waiting until weeds had reached maturity. Rarely were differences among termination methods observed, however a trend in common lambsquarters towards increased seed production following a glyphosate application compared with cutting or chopping may warrant further investigation with an increased number of replications and multiple populations. Perhaps seed development is allowed to continue longer during the time it takes glyphosate sprayed weeds to desiccate and die. University of Maine: Due to budget and staffing limitations, the University of Maine research group did not conduct field experiments related to Objective 2 in 2013. University of Delaware: Methodology followed Michigan State; species examined were jimsonweed, giant foxtail, and velvetleaf. Unless weeds were killed at or very shortly after flowers, viable seeds were formed. Jimsonweed seed production was not consistently affected by termination methods. Velvetleaf and giant foxtail produced more viable seeds when cut than chopped or sprayed at the brown seed stage. <br /> <br /> Objective 3 results - Determine the extent to which soil amendments such as green manures and compost affect seed mortality of various weed species. <br /> Cornell – To explore the effects of cover crops on the survival of weed seeds in the soil, in Nov 2011 we buried mesh bags of common lambsquarters (LQ), Powell amaranth (PA), velvetleaf (VL) and giant foxtail (GF) seeds mixed with sand into plots of rye, hairy vetch or a bare control. Bags were recovered in May 2012 and either evaluated for viability or the contents mixed with the equivalent of 600 g per sq m of chopped cover crop and reburied. All plots had sorghum-sudangrass harvested as forage in the summer and were no-till planted with the same cover crops in Sep. Samples were recovered in May 2013 and treated as in 2012. Sorghum-sudangrass was again grown summer 2013 and cover crops planted in Sep. A third set of bags will be recovered in 2014, and a second set of seed bags was buried in Nov 2013. Viability did not differ between treatments in samples recovered in 2012. For 2013 samples, VL seeds survived better in rye than in hairy vetch or control. Marginally significant trends indicated LQ and PA seeds may have survived better in control than in hairy vetch, with intermediate survival in rye. This may be due to release of N from hairy vetch triggering inappropriate germination these nitrate sensitive species. Similarly, we (Bjorkman, Taylor) sequentially buried bags containing pigweed or foxtail seeds into living and killed buckwheat and sudangrass. Collected bags and assayed for sprouted, non-dormant, and dead seeds. Weed seed mortality was not affected by living cover crops or by their resides after the crops were terminated. Event the cyanide release from sudangrass during decomposition had no effect. Small changes in dormancy were observed but not enough to use for weed management. Purdue University: Methods followed those described above but lambsquarters, velvetleaf, and redroot pigweed were buried and recovered. Weed seed survival and germination was not affected by the cover crop treatments. Michigan State University (Brainard, Haramoto): Survival of buried weed seeds (Amaranthus powellii and Digitaria sanguinalis) was evaluated in a long-term trial examining the effects of cover crops (none, rye or rye-vetch) and tillage (moldboard plow vs strip-till) on weeds in a three-year vegetable crop rotation (sweet corn (2009, 2012): snap beans (2010, 2013): winter squash (2011, 2014)). Cover crop and tillage treatments have been imposed in the same plots since 2009. Seeds were buried following winter squash harvest in fall 2011, exhumed in spring 2012 and spring 2013, and tested for viability. Sufficient additional bags have been buried to examine survival for 2 additional years. One bag of each species from each plot was exhumed on 29 May 2013. Bags were stored at 4°C until they were opened, spread into a thin layer, and dried at room temperature. Seeds were separated from the sand and residue by sieving through a 500 µ sieve and stored at room temperature until viability testing. Seeds of both species were then germinated at 30°C with 2 µM GA. Ungerminated seeds were assessed for viability by a combination of squeeze testing and TZ testing. Seeds were characterized as germinated, dormant (did not germinate but were TZ viable), or dead; germinated and dormant seeds were considered viable. In moldboard plow treatments, all remaining bags were pulled prior to spring tillage, filled with a fixed amount of cover crop residue, and re-buried following tillage and planting the next day. Bags were filled with rye and vetch residue that had been collected prior to termination (15 May 2013), dried down, and coarsely ground in a Wiley mill. Pieces of ground residues were approximately 5-10 mm long. Experiment-wide, dry rye biomass averaged 2400 kg/ha in rye only plots and 2940 kg/ha with 560 kg/ha vetch biomass in rye/vetch plots. For rye plots, we added 0.13 g of dry rye residue per bag; for rye and vetch plots we added 0.13 g dry rye and 0.027 g dry vetch residue. Results. In 2013, more viable AMAPO seeds were recovered from ST than from MBP; 43% of AMAPO seeds recovered in ST were still viable while only 4% of those recovered from MBP were viable. Within each tillage type, the cover crop species did not affect AMAPO viability. Seeds within MBP were excavated and mixed with cover crop residue (or just mixed to stimulate tillage for plots without cover crops) in June 2012, while those in ST were buried continuously since November 2011. It is possible that removal and reburial of seeds in MBP treatments promoted more fatal germination than ST treatments due to greater exposure to light, oxygen or other germination stimuli. In 2013, no effects of tillage or cover crop on DIGSA viability were detected, and survival was less than 10% in all cases. Large variability in DIGSA survival—especially in strip-tillage treatments—limited our ability to detect significant differences. Michigan State University (Renner, Hill): Lambsquarters, giant foxtail, velvetleaf were buried as described above but a higher rate of cover crop biomass, equivalent to 6.2 g DW per bag, was used and bags were recovered at 0, 1,2,4,6, and 12 months. Legure cover crops did not increase weed seed mortality compared to the no cover-crop treatment. High rates of rye appeared to increase weed seed persistence. <br />Publications
Kordbacheh, F., C.L. Mohler, A. DiTommaso, and H. Rahimian Mashhadi. 2013. Effects of different cutting methods and timing on seed viability and germination of three annual weed species. Abstracts from the Joint Annual Meeting of the Weed Science Society of America and Northeastern Weed Science Society. February 4-7, Baltimore, MD. No. 195.<br /> <br /> Mohler, C.L., B. Caldwell, C. Marschner, and A. DiTommaso. 2013. Mortality of weeds due to tine weeding and inter-row cultivation in corn and soybeans. Abstracts from the Joint Annual Meeting of the Weed Science Society of America and Northeastern Weed Science Society. February 4-7, Baltimore, MD. No. 248.<br /> <br /> Bellinder, R. 2013. Herbicide research report for processing vegetables. Proceedings of the Empire State Producers Expo January 22-24, 2013, Syracuse, NY.<br /> <br /> Bellinder, R. 2013. Evaluating new herbicides for cabbage—2012. Proceedings of the Empire State Producers Expo January 22-24, 2013, Syracuse, NY.<br /> <br /> Mohler, C. L. 2013. Webinar: Crop rotations for Diversified Farms. NRCS, Portland OR Office. Given June 8, 2013. On line at http://conservationwebinars.net/webinars/crop-rotations-on-diversified-farms<br />Impact Statements
Date of Annual Report: 06/25/2015
Report Information
Annual Meeting Dates: 03/24/2015
- 03/24/2015
Period the Report Covers: 10/01/2013 - 09/01/2014
Period the Report Covers: 10/01/2013 - 09/01/2014
Participants
Erin Hill; Kevin Gibson (past chair 2014); Chuck Mohler; Robin Bellinder;Toni DiTommaso; Russ Hahn; Steven Mirsky; Carlene Chase; Alan Taylor; Eric Gallandt; Bill Curran; Markah Frost (Brainard group); Thomas Björkman; Mark VanGessel; and Karen Renner (Chair 2015)
Brief Summary of Minutes
MINUTES NE-1047 Conference Call MeetingTuesday, March 24, 2015
11:30 am EST
Meeting convened at: 11:35 am
Members attending: Erin Hill, Kevin Gibson (past chair 2014), Chuck Mohler, Robin Bellinder, Toni DiTommaso, Russ Hahn, Steven Mirsky, Carlene Chase, Alan Taylor, Eric Gallandt, Bill Curran, Markah Frost (Brainard group), Thomas Björkman, Mark VanGessel, and Karen Renner (Chair 2015)
Members not attending: Erin Haramoto, Dan Brainard, Fred Servello
Objective updates:
Objective 1: Determine how soil conditions affect efficacy and selectivity of cultivation implements for the control of various weed species. (Bill and Eric)
Bill Curran (poster): Clair Keene thesis project. This work is done and being written up in Claire’s thesis with expected defense in late summer 2015. Topic: high-residue cultivation as part of IWM for inter-row weed control in no-till soybean and corn. Residue/no residue did not really impact results (though it was a small amount of residue due to management with herbicides sprayed 1 week before planting, 2-3,000 lbs dry matter). Timing and frequency of cultivation were the most important. High residue cultivators are different than conventional cultivators, intended to use later in the season for control of larger weeds. Results: Run twice to get good weed control. This project was done for 3 years (2 corn; 3 soybean) and so this work is complete. Farmers are not interested in adopting this practice. No-till farmers do not want to disturb the soil at all. Trash wheels included on no-till planter. Banding herbicides worked well; no negative interactions with cover crop residue. They plan to publish a paper in a refereed journal from this research.
Eric Gallandt: They did 3 years looking at cultivation efficacy vs soil/residue parameters…not a lot of success. They are interested in switching to the potential for natural populations of weed seedlings to be the source of variability in cultivation success (first year of research in 2014). They evaluated the early growth rate of four weed species, cotyledon through 6-8 leaves and included growth rate, root/shoot partitioning, root architecture. They are processing the data to determine how these parameters influence cultivation efficacy or variability in efficacy. Ex. Crabgrass with one leaf has a large root system…efficacy of cultivation drops off quickly as growth in crabgrass progresses.
Objective 2: Determine the reproductive growth stage at which summer annual weeds can be
terminated and still produce viable seeds and quantify the effect of method of life-termination
on seed production.
Erin Hill and Karen Renner: We presented our poster from WSSA. This work is done and is currently in the process of being submitted as a manuscript to Weed Science in April 2015. Mark VanGessel: Presented poster from WSSA. The poster focused on the short amount of time between flowering and viable seed formation, and concluded that there are about 2 weeks to control weeds after flowering before seeds form. Next step is formulating a fact sheet and make it available on a site such as eOrganic. Mark would like to include photos of the flowering stages of these species. Eric G. will send photos of Hairy galinsoga. This project was completed in 2013. No future trials related to this project are projected for 2014.
Robin Bellinder: Completed common ragweed data set in 2013 and 2014. The 2014 data is still being processed. She is interested in the possibility of included the common ragweed data set in the MSU and DE publication (common ragweed was not a species in MI or DE).
Objective 3: Determine the extent to which soil amendments such as green manures and compost affect seed mortality of various weed species.
Erin Hill and Karen Renner (report): We gave a brief summary of our report, highlighting the differences with the other Universities (shorter pull times, higher cover crop rates, organic system with more disturbances). This work is complete. It was included in Erin Hill’s dissertation and was recently submitted as part of an article to Weed Science.
Thomas Bjorkman (report): Gave a summary of his report. They were interested in knowing if a growing cover crop and/or a decomposing cover crop kill weed seeds? Weed seeds included foxtail (ended up being dead) and redroot pigweed. Buckwheat and sorghum sudangrass did not appear to impact weed seed mortality in their research.
Markah Frost, Dan Brainard, Erin Haramoto (report): Report will be sent out to the group was sent out at 3 p.m. today. The last seed bags were pulled up in 2014 and they are in the final phases of processing seed bags. Powell amaranth and large crabgrass were the two weed species studied; cover crops included rye and rye + hairy vetch under two tillage regimes (i.e. strip tillage and moldboard plow). Strip tillage increased longevity of P. amaranth seeds compared to moldboard plow; large crabgrass had low viability across all experimental treatments. Faucets of this project may continue, but they are uncertain at this time.
Chuck Mohler (slides): Run 1 done, Run 2 underway but will not be done until spring 2016.
Trtmts- Rye, hairy vetch, bare ground control (planted in same plots in all years)
Species- Powell amaranth, C. lambsquarters, velvetleaf, giant foxtail
Pull times- 6 months, 1.5 and 2.5 years after burial (Run 1 fall 2011, Run 2 fall 2013)
Results
Mortality often higher following hairy vetch (proposed mechanism=release of N stimulating germination deep in the soil)
No pattern following rye, inconsistent
Questions to the group
Is the statistical analysis appropriate (i.e. logistic regression)?
Convert to % of initial (% mortality)- Erin Hill and Bill
Eric- Logistic regression, doesn’t require replications, more x values is what is wanted.
How do we know we have enough x values to compensate for replications?
Steven- modeled as a % of the total, if the span of x values desired isn’t covered then it would be appropriate
Carlene- analyzing count data using Proc GLIMMIX (Chuck using GENMOD)
Conclusion: need to consult with a statistician on this data set
Carlene Chase- Initially had bags in the ground, but lack of personnel led to dismissing the project. Currently working on another related project, looking at cover crops to suppress weeds during the off season (summer time) and for Sting nematode control in strawberry (see report emailed out). Cover crops included: sunhemp, hairy indigo, American joint vetch, and short-flower rattlebox. Good results for weed suppression, in addition to data analysis did an evaluation of stakeholder interest. They were interested in these cover crops and mixtures. Stakeholders want a cover crop that they can get $$ for. Last year they used the cover crops in a 4-way mixture and also included sesame. Sunhemp dominated the mix.
Annual report is due 60 days following the annual meeting. Kevin sent a report in for 2013-2014. Karen needs to send in the report for 2014-2015 by May 25 if there is no summer annual meeting. This project terminates in September 2016. Someone from this group will need to chair the group in 2016 and write the final report. If the group plans to rewrite a renewal – this should be started in July/August of this year with the renewal turned in spring 2016.
Summer meeting:
Who can go? What dates work well? Where? Focus on future direction.
Summary: Reaction not overwhelming to continue. The number of people who would participate depends on the focus area. It sounded like we need to float project ideas around and then based on who is interested in setting up a meeting time and place, if enough interest is generated.
Do we want to collaborate or merge with NC1191 group?
Summary: Uncertain if we want to collaborate. It would depend on their chosen focus.
Individual comments
Eric: Enthusiasm is high during the writing year, then without extra support we aren’t able to carry out all of the plans. Interest depends on the focal area. Keeping it very focused is important.
Mark: Like idea of concept, rewarding, but moving forward we need to write a proposal that even those with limited resources could participate and contribute. Keep it focused so that when we are all done the outcomes align and can be written together. Maybe just have one objective with a uniform protocol. We need to be able to come out of this with a manuscript.
Chuck: Does not plan to participate; technically retired for the past 4 years.
Toni: Cover crop impact on weed seed mortality was not significant enough to reduce the weed seed bank. He doesn’t want to keep on with this portion of the project because of the results.
Russ: Unlikely to participate in future projects.
Bill: Inquired about what the NC group was doing.
Steven: Happy to participate if the subject matter is of interest. There is probably no need to continue with the seed decay portion. He would like a simple common experiment. Summer meeting would work, depends on where. Beltsville would be good.
Alan: Enjoys multi-state projects and sees the benefits. Some funding opportunities come to them as a result of participating in the multi-state project. Specifically participated because 2 of 3 objectives had a seed component which is why he was invited on. If the new focus is nonseed, Alan will not likely participate.
Carlene: Would rather spend time working on a grant together. Same comment that focus needs to be simple. Focus would need to be applicable to FL cropping systems. Would like to collaborate, but is not counting on it because of the differences.
Dan/Markah: Get in touch with him in mid-May to see his interest in future participation.
Kevin: His interest is waning. Initially had resources, but couldn’t continue. Future participation would really depend on what the topic was.
Chuck: Propose an idea, send it around, see who is interested, and then those that are interested need to rally together.
Erin/Chuck: What are we already doing that would be of interest with multiple locations?
Carlene: Has interest in developing weed seed suppressive soils over time. Can we do it? Maybe we aren’t affecting the soil microbial biomass as much as we would like to in the short-term, but in long-term we may. Interested in soil health over time, how does this impact the weed suppressiveness of the soil over time? After 4 years there may be additive results. Look at reduced tillage practices and expect that it will have longer lasting impacts. Cover crop mixtures also of interest, but will have to work well in the south as well as in the north.
Meeting concluded at: 1:05 pm EST
Minutes submitted by Erin Hill