NE1000: Improved Weed Control Through Residue Management and Crop Rotation

(Multistate Research Project)

Status: Inactive/Terminating

Project Menu

SAES-422 Reports

Annual/Termination Reports:

[03/02/2001] [04/04/2003] [04/17/2006]

Date of Annual Report: 03/02/2001

Report Information

Annual Meeting Dates: 02/11/2001 - 02/11/2001
Period the Report Covers: 01/01/2000 - 12/01/2000

Participants

J. Scott Angle, Admin. Advisor - MD;
Ed Beste - MD;
Nancy Creamer - NC;
Chris Reberg-Horton - NC;
Robin Bellinder - NY;
Chuck Mohler - NY;
John Teasdale - MD;
Eric Gallandt - ME;
Doug Doohan - OH;
Jim Burton - NC;
Antonio DiTommaso - NY

Brief Summary of Minutes

Minutes Attachment:

Attachment

Accomplishments

Cooperating Agencies and Principal Leaders: W. Asbil* - Kemptville College, Univ. of Guelph R. Ashley* - Univ. of Connecticut R. R. Bellinder* - Cornell Univ. C. E. Beste* - Univ. of Maryland J. Cardina* - Ohio State Univ. N. Creamer* - North Carolina State Univ. A. DiTommaso* - Cornell Univ. D. Doohan* - Ohio State Univ. E. Gallandt* - Univ. of Maine P. Johnston-Berresford* - Kemptville College, Univ. of Guelph C. L. Mohler* - Cornell Univ. J. R. Teasdale* - USDA-ARS Beltsville Progress of the Work and Principal Accomplishments: The year was a transition year between the old NE-92 project and the new NE-1000 project. Research continuing over from the NE-92 project is reported first. Rye variety trials begun under NE-92 are reported under NE-1000 since they meet objective 3 of the NE-1000 Project Outline and will continue under NE-1000. NE-92 objective 1, Cover crop management and objective 2, Cultivation. Combining cultivation and interseeded cover crops for weed control in transplanted cabbage, broccoli and tomato. Cabbage (NY): Cabbage was cultivated 10, 20, and 30 days after transplanting (DAT) and interseeded either at the second or third cultivation with hairy vetch or oat. Vetch was regulated with a low rate of clopyralid and oats with sethoxydim at the point when the cover crops reached the same height as the crop. Regulation was compared to non-regulation, handweeding, a chemical standard and a weedy check. Results indicated that with regulation, both vetch and oats could be seeded 20 DAT without yield reduction in cabbage. Unlike some previous trials, in 2000 unregulated vetch seeded 20 DAT significantly reduced yield. Oat needed regulation when seeded at both times to avoid yield reductions. Weed biomass was reduced 85 and 94% for both cover crops seeded at 20 and 30 DAT, respectively. Weed biomass suppression with cultivation alone 30 DAT (3x) was equivalent to that provided by the cover crops but when cultivated only 2 times, weed suppression by the cover crops was 22% greater. Fall-planted Broccoli (NY): This experiment was repeated in 2000 and will be done again in 2001. Broccoli was cultivated 0, 1, or 2 times at 10 day intervals, with or without rye inter-seeded at the final cultivation. Weedy, weed-free, and a chemical standard were included. A single cultivation 10 DAT was necessary and sufficient to avoid significant broccoli yield loss. Rye did not suppress yield when seeded at 10 DAT but did suppress yield when seeded at transplanting. When seeded 20 DAT rye did not establish well. Although pigweed (Amaranthus spp.) and hairy galinsoga (Galinsoga ciliata) that escaped cultivation did not suppress yield, they set seed prior to broccoli harvest. Tomato (MD): Lana woolypod vetch was seeded at three rates and purple vetch at two rates before or after cultivation 17 DAT processing tomato. Seeding before cultivation resulted in greater vetch biomass, but biomass was unaffected by seeding rate. Woolypod vetch produced significantly more biomass than purple vetch. When seeded before cultivation, woolypod vetch plus uncontrolled weeds reduced yield; other vetch treatments did not reduce yield. Vetch appeared to suppress weeds, but not significantly. NE-92 objective 3. Modeling and weed biology relevant to model paramaterization. Relation of seed size to emergence through rye residue An experiment was run in NY to test the ability of crop and weed species with different seed sizes to emerge through dead rye residue. Five weed species and 11 crop species ranging in seed weight from 0.5 to 414 mg were planted in small field plots and covered with 0, 0.25, 0.5, 1, 2 or 4 kg m2 of rye straw. For this year, as in previous years, the rate of decline in emergence with increasing mulch was a power function of seed mass. NE-1000 objective 1. Mechanical weed management in high residue. Rye was planted for this experiment in ME, NC, NY, OH, and ARS Beltsville. NE-1000 objective 3. Cover crop variety trials. Subterranean clover ARS Beltsville evaluated 451 accessions of subterranean clover at two sites in MD for vigor, winter hardiness and density of leaves and stems. Due to the mild winter (1999-2000) most varieties survived until spring. The best performing accessions were planted again in September 2000. Rye Commercially available cultivars of rye (nine in NC and 8 in NY) were evaluated for their ability to suppress weeds. The rye was planted in the fall of 1999 and biomass production, allelopathic activity, and weed suppression in the field were assessed in summer 2000. Unlike the 1999 results from NC but similar to 1999 results from NY, the varieties showed no difference in weed suppression in the field. Wrens 96 and Wrens Abruzzi produced most biomass in NC, whereas Aroostook was the most productive in NY and Wrens Abruzzi performed poorly. An extract bioassay (NC) and a straw bioassay (NY) both showed Wheeler as having the highest allelopathic activity. In both cases, only certain test species were affected. Concentrations of DIBOA, an important rye allelotoxin, were assessed in the NC experiment. By flowering, DIBOA concentrations were low in all varieties, indicating that allelopathy demonstrated in the bioassay was due to some other compound(s). Eleven commercial varieties were planted at MD, NC, NY, and ON in fall 2000 for evaluation in 2001. In addition, 280 rye accessions from the National Small Grains Collection were planted at NC. The best of these will be used to initiate a breeding program for cover crop rye. NE-1000 objective 4. Weed management in crop rotation. A faming systems trial at ARS-Beltsville initiated in 1996 continued to compare weed seedbanks, weed density and biomass in two, three and four year rotations with organic weed management. A long-term trial focused on potato in ME was modified to compare two and four year crop rotations each with and without soil amendment (cover crop green manure plus manure). Organic amendments increased potato yield 27% in 2000. Mechanical weed control was highly effective. Usefulness of Findings Inter-seeding trials will allow development of recommendations on best species, timing and methods for using inter-seeded cover crops to suppress weeds and improve soil in vegetable cropping systems. Results from the experiment relating seed size to emergence through rye residue will allow extension of the model reported in Teasdale and Mohler (2000) (see publications). This will generalize growers ability to predict the degree of weed suppression that can be expected from a given amount of mulch. Results from the rye variety trial will allow recommendations of best adapted varieties for use as weed suppressive mulch in various climatic zones within the region. Results from the subterranean clover trials are expected to extend the range for this highly weed-suppressive cover crop into colder climatic zones. The crop rotation experiments will allow recommendations on optimal crop sequences for maximum crop production and improved weed suppression with reduced herbicide inputs. Work planned for next year Work will proceed as specified in the Project Outline except for objective 1. For all objectives, additional locations will initiate work as indicated in the Project Outline. The experiment for objective 1, Mechanical management in high residue has been modified. Rye will be killed by mowing at heading to prevent regrowth and enable movement of the residue into the crop row. Tillage treatments will contrast chisel/disk vs. zone tillage. Movement treatments within zone-till will be: (a) residue not moved; (b) residue moved into the crop row at planting; (c) residue moved at 2 leaf corn or 1st trifoliate soybean; (d) residue moved at 4 leaf corn or 3rd trifoliate soybean or layby. These treatments will be split to compare in-row residue effects where the in-row weeds are removed prior to residue movement vs. in-row weeds not removed but buried by the residue. All treatments will receive inter-row cultivation.

Publications

<ul><li>Publications Issued or Manuscripts Approved During the Year:</li> Refereed Journal Articles (in print): 2 Proceedings Abstracts (in print): 3 <li> Refereed Journal Articles:</li> Bellinder, R. R., J. J. Kirkwyland, R. W. Wallace, and J. B. Colquhoun. 2000. Weed control and potato (Solanum tuberosum) yield with banded herbicides and cultivation. Weed Technology 14:30-35. Teasdale, J. R. and C. L. Mohler. 2000. The quantitative relationship between weed emergence and the physical properties of mulches. Weed Science 48:385-392. <li>Abstracts in Proceedings:</li> Teasdale, J. R. and C. L. Mohler. 2000. The physical properties of mulches contributing to weed suppression. Third International Weed Science Congress, Foz do Iguassu, Brazil, June 6 to 11, 2000, Abstracts, pp. 95-96 (No. 204). Mohler, C. L. 2000. Seed size controls the ability of seedlings to emerge through rye mulch. WSSA Abstracts, 2000 Meeting of the Weed Science Society of America 40:98, (No. 235). Reberg-Horton, C., N. G. Creamer and C. L. Mohler. 2000. The suppression of weeds by nine varieties of rye (Secale cereale). WSSA Abstracts, 2000 Meeting of the Weed Science Society of America 40:27-28, (No. 66). </ul>

Impact Statements

Date of Annual Report: 04/04/2003

Report Information

Annual Meeting Dates: 02/09/2003 - 02/09/2003
Period the Report Covers: 01/01/2002 - 12/01/2002

Participants

Brief Summary of Minutes

Minutes Attachment:

Attachment

Accomplishments

Objective 1. Mechanical weed management in high residue. In Maryland, an experiment was conducted in a field with two cover crop treatments, rye planted at 90 lb/A and rye plus crimson clover planted at 60 + 20 lb/A. Before planting soybeans, cover crops in a portion of this field were bailed and removed from the field. Soybeans were planted into the bailed areas or into the standing cover crops on May 22. On the same day, cover crops were flail mowed or rolled. The following treatments were established in the flail mowed area: 1) no rye movement, 2) rye moved into the row on the same day as, but after planting, 3) rye moved into the row on June 18 when soybeans were tall enough to remain uncovered, 4) rye moved out of the row on the same day as, but after planting, and 5) rye moved out of the row on the same day as planting and into the row on June 18. Plots were cultivated with a Buffalo high residue cultivator. Soybean stand was higher in rye than in rye plus crimson clover (246,000 versus 157,000 plants/ha). Stand was higher in the bailed than in the flail mowed and rolled treatments (281,000 versus 143,000 and 180,000 plants/ha, respectively). In both cases, higher stand reductions were associated with higher residue biomass levels. Weed cover within row was inversely correlated with soybean stand. Normally, higher residue levels would be expected to reduce weed emergence and growth but in this experiment the opposite occurred suggesting that the competitiveness of the soybean canopy was more important than the mass of cover crop residue in suppressing weeds. Mulch movement treatments 1 through 5 were all planted into similar residue levels followed by flail mowing so soybean stand was not an issue for comparison of these treatments. Weed cover in the row was lower in treatments 2 and 3 where mulch was moved into the row than in treatments 1, 4, and 5. However, weeds (primarily annual grasses) eventually developed to unacceptable levels in all plots by August. These results suggest that mulch movement can reduce weed pressure within the row. However, it is imperative that good crop stands become established since a competitive crop is apparently essential for this system to provide effective full season weed control. In New York, Rye was planted in the fall of 2001 for a complimentary experiment, but extremely wet weather prevented tillage until early June. At that time the soil moisture was highly heterogeneous and the prospective planting date was extraordinarily late. Consequently, the experiment was cancelled since it was unlikely to provide meaningful data. ?Aroostook? rye was planted on 9/26/02 at 111 lb/a with 100 lb/a of 15-15-15 fertilizer for a repeat of the 2001 experiment in 2003. Objective 2. Effects of mulch on soil moisture and weed emergence. Cover crop residues may affect weed establishment through changes in soil temperature and available soil water. In New York, trials evaluating the germination of seeds of barnyardgrass, giant foxtail, and velvetleaf in solutions of various osmotic potential were carried out. A significant (P < 0.05) species by osmotic pressure interaction was found. For the 3 trials combined, germination of velvetleaf was inhibited by moisture potentials below ?30 kPa whereas giant foxtail germination peaked at -100 kPa and then decreased steadily, especially at moisture potentials above ?300 kPa. The germination of barnyardgrass seeds appeared least negatively affected by increasing osmotic potential. Highest germination levels for this species peaked at the -300 kPa level with a surprising 40% of seeds germinating at the -1000 kPa level. By contrast, no velvetleaf seeds and only 3% of giant foxtail seeds germinated under these extremely dry conditions. The rate of germination was delayed by decreasing moisture potentials for all species. Technical difficulties related to the establishment of appropriate soil moisture potential levels in pots have delayed the start of trials assessing the effect of soil moisture potential on weed emergence in sealed pots. Objective 3. Cover crop variety trials. Subterranean clover Subterranean clover germplasm evaluations have identified very few lines that exhibit winter hardiness or vigor equivalent to or better than the current standard, Mt. Barker. Rye Maine. Eight rye varieties were tested at Stillwater, Maine, for winter survival, biomass production and weed suppression. All the varieties overwintered. Biomass production was consistently in the 4,000-5,000 kg/ha range except for ‘Maton‘ which produced an average of 6, 340 kg/ha. Weed suppression was fairly uniform amongst the plots, probably due to low weed pressure and droughty conditions. A wider testing of rye genetic material was planted in Orono in September of 2002. A total of 268 rye accessions from the National Small Grains Collection were planted to look at winter survival, heading date, and production of the allelochemical DIBOA (2,4-dihydroxy-1,4-(2H)benzoxazine-3-one). DIBOA will be quantified 3 times during the spring for all accessions using an experimental colorimetric technique adapted from wheat breeding programs. Maryland. On October 30, 2001, nine rye varieties were drilled in 19 cm row widths with four replications. Glyphosate, 1.7 kg/ha was applied on May 6 and rye was sickle bar mowed on May 20, 2002. Rye plant population was moderately influenced by seed size probably due to variable germination; however, erratic seed viability appeared to have a greater influence on plant population than seed size. ?Wrens Abruzzi? had the greatest biomass of 3,900 kg/ha dry weight, but not significantly different from the varieties listed in descending order of biomass as follows: ?Wrens 96?, ?Early Grazer? and ?Elbon?. The biomass of other varieties in descending rank were as follows: ?Wheeler?, ?Oklon?, ?Maton?, ?Aroostook? and ?variety not specified?. All rye varieties, except ?variety not specified?, significantly reduced weed growth and ?Wrens Abruzzi?, ?Wrens 96?, ?Wheeler? and ?Oklon? provided the best weed control. Nitrogen fertilizer reduced weed suppression by rye straw biomass. Significant differences of anthesis over a 3 week period between rye varieties indicated varieties could be selected for specific spring periods for mechanical control after flowering. New York. A trial comparing 8 varieties of rye and a bare control treatment was repeated for a fourth year. Varieties differed greatly in density in late fall, with Maton, Aroostook, Elbon and Wheeler establishing well but Wrens 96 and Wrens Abruzzi establishing poorly. Aroostook, the most northerly adapted variety, produced about twice the biomass of Wrens 96 by May 25, but otherwise biomass production among varieties did not differ significantly. Powell amaranth (Amaranthus powellii) and dandelion (Taraxacum officinale) were the major weeds this year. Neither of these species, nor total weeds, showed any response to rye variety this year. Objective 4. Weed management in crop rotation. In Ohio, the effect of three intensities of weed management was evaluated in the second year of a 4-year rotation study involving red clover, field corn, soybean and sweet corn. Mechanical weed control (hand hoeing) provided better control of annual grasses than did low- and high-rate herbicide programs. Full rate herbicides did not improve annual grass control over that obtained with low rate, and in the case of field corn, decreased grass control. Due to severe drought sweet corn was not harvested. Yield of soybean and field corn were low but unaffected by weed management system. Although weed communities were clearly affected by management, in no instance was weed control with herbicides improved when high-rate programs were used, relative to control obtained with low-rate herbicides. Also in Ohio, a field experiment was established to 1) determine if No-seed Threshold (NST) and Critical Period of Competition (CP) were cost effective approaches to weed management during transition to organic and following certification; 2) to investigate the effects of NST and CP on crop performance during transition; and 3) to estimate the viable weed seed remaining in the weed seed bank each year. The field experiment was a 3-year rotation of winter wheat, oat/red clover, tomato, and cabbage. In 2001 and 2002, a total of 24 main plots and 48 subplots of cabbage and processing tomato were established. The total time taken to hoe/weed both NST and CP plots in cabbage and tomato crops during 2001 and 2002 was 20 h and 14 h, respectively. The additional hours taken to hoe/weed NST plots for each crop were 13 and 4 h for tomato, whereas those in cabbage were 12 and 3 in 2001 and 2002, respectively. In Maine, a three-acre systems comparison was established in the spring of 2001. In four contrasting systems, this 4-year project will determine the annual and long term effects of contrasting 2- and 4-year cover crop based vegetable rotations on weed population dynamics, selected soil quality parameters, and crop yield, quality, and system profitability. To determine whether these cover-cropping practices affect resident invertebrate seed predators, we characterized the activity-density of seed predators by pitfall trapping over a 72 h period. There was greater density-activity of Harpalus rufipes in vegetated plots compared to those recently tilled and planted to a fall cover crop of oat (e.g., compare None, tilled to Winter Squash and Red clover). To measure seed predation, 25 seeds of each of six weed species were placed in the field. Seed recovery after 10 days in the field was 89% with vertebrate + invertebrate exclosures, intermediate at 55% with the vertebrate exclosures, and least at 43% with no exclosure (P < 0.001). Weed dynamics continue to be followed in the Maine Potato Ecosystem Project. In 2002 density of germinable seeds, and thus potential weed pressure, was greater following soybean (10,218 germinable weed seeds per sq. m to 10 cm depth) than following each of the other crops in the rotation (Contrast P < 0.001; potato, 2863; barley, 4503; or forage, 2578 per sq. m. Weed control in potato was excellent across the pest management systems and was unaffected by soil management (grand mean 0.6 g per sq. m; median 0.0 g per sq. m). In New York, crop rotation research was sited on new land purchased by the University from a neighboring farmer. The site had been in continuous alfalfa for five years. Prior to planting, the plots were marked out and soil samples taken for characterization, weed seed germination, and elutriation. Sweet corn was subsequently planted in all plots and three different levels of weed control were initiated: 0 chemical control, 0.33X (1X rate applied to a 10 inch band), and 1X herbicide rates. Plots receiving no herbicides were cultivated four times, beginning with a broadcast flex-tine weeder, followed by a Buddingh in-row finger weeder, and then a between-row S-tine cultivator (twice). Plots receiving the 0.5X banded herbicide rates were cultivated twice with the S-tine cultivator. The broadcast 1X treatments did not require cultivation in 2002. Field counts and soil germination results both identified 12 species and 8 of these were found with both methods. The elutriation technique identified 19 species, all of which were found by both of the other two methods. Species not seen in field counts and germination tests were most frequently winter annuals. The germination soil samples were frozen and have just recently been returned to the greenhouse for an additional germination period. The most frequent species in the trial as a whole were, in order of magnitude, galinsoga, redroot pigweed, and common lambsquarters. Galinsoga was by far, the most numerous but counts ranged from 2 to 5 in OX treatments in Rep 1 to 85 to 400+ in the same treatments in Rep IV.

Publications

Complete Listing of NE-1000 Publications Refereed Journal Articles (in print): 15 Proceedings Abstracts (in print): 8 Theses: 1 Refereed Journal Articles: 1. Bellinder, R. R., J. J. Kirkwyland, R. W. Wallace, and J. B. Colquhoun. 2000. Weed control and potato (Solanum tuberosum) yield with banded herbicides and cultivation. Weed Technology 14:30-35. 2. Brainard, D.C. and R.R. Bellinder. 2001. Effect of cultivation and interseeded cover crops on weed suppression and cover crop establishment in transplanted kale and broccoli. Brighton Crop Prot. Conf. (Weeds) 2001 1:321-324. 3. Caldwell, B. and C.L. Mohler. 2001. Stale seedbed practices for vegetable production. HortScience 36:703-705. 4. Conklin, A.E., M.S. Erich, M. Liebman, D. Lambert, E.R. Gallandt, and W.A. Halteman (2002). Effects of red clover (Trifolium pratense) green manure and compost soil amendments on wild mustard (Brassica kaber) growth and incidence of disease. Plant and Soil 238:245-256. 5. Liebman, M. and E.R. Gallandt (2002). Differential responses to red clover residue and ammonium nitrate by common bean and wild mustard. Weed Science 50:521-529. 6. Liebman, M., and C.L. Mohler. 2001. Weeds and the soil environment. Pp. 210-268, in, Ecological Management of Agricultural Weeds, M. Liebman, C.L. Mohler and C. Staver. Cambridge University Press, Cambridge. 7. Liebman, M., C.L. Mohler and C. Staver. 2001. Ecological Management of Agricultural Weeds, M. Liebman, C.L. Mohler and C. Staver. Cambridge University Press, Cambridge. 8. Mohler, C. L. 2002. Mechanical weed control in agriculture. Encyclopedia of Pest Management, Supplement 2., David Pimentel, ed. Marcel Dekker: New York. Electronic publication at www.dekker.com. 9. Mohler, C.L. 2001. Enhancing the competitive ability of crops. Pp. 269-231, in, Ecological Management of Agricultural Weeds, M. Liebman, C.L. Mohler and C. Staver. Cambridge University Press, Cambridge. 10. Mohler, C.L. 2001. Mechanical management of weeds. Pp. 139-209, in, Ecological Management of Agricultural Weeds, M. Liebman, C.L. Mohler and C. Staver. Cambridge University Press, Cambridge. 11. Mohler, C.L. 2001. Weed evolution and community structure. Pp. 444-493, in, Ecological Management of Agricultural Weeds, M. Liebman, C.L. Mohler and C. Staver. Cambridge University Press, Cambridge. 12. Mohler, C.L. 2001. Weed life history: Identifying vulnerabilities. Pp. 40-98, in, Ecological Management of Agricultural Weeds, M. Liebman, C.L. Mohler and C. Staver. Cambridge University Press, Cambridge. 13. Mohler, C.L., M. Liebman, and C. Staver 2001. Weed management: The broader context. Pp. 494-581, in, Ecological Management of Agricultural Weeds, M. Liebman, C.L. Mohler and C. Staver. Cambridge University Press, Cambridge. 14. Sawma, J. T. and C. L. Mohler. 2002. Evaluating seed viability by an unimbibed seed crush test in comparison with the tetrazolium test. Weed Technology 16:781-786. 15. Teasdale, J. R. and C. L. Mohler. 2000. The quantitative relationship between weed emergence and the physical properties of mulches. Weed Science 48:385-392. Abstracts in Proceedings: 1. Gallandt, E.R. (2001) Controlling Problem Weeds with Cover Crops. New England Vegetable and Berry Growers Conference Proceedings. 2. Mohler, C. L. 2000. Seed size controls the ability of seedlings to emerge through rye mulch. WSSA Abstracts, 2000 Meeting of the Weed Science Society of America 40:98, (No. 235). 3. Mohler, C.L. and J.C. Frisch. 2001. Measurement and modeling of depth changes of weed seed surrogates during tillage. WSSA Abstracts, 2001 Meeting of the Weed Science Society of America 41:113-114 (No. 274). 4. Nurse, R.E. and A. DiTommaso. 2002. Influence of photoperiod on barnyardgrass seed germination and seedling vigor. Proceedings of the 56th Annual Meeting of the Northeastern Weed Science Society of America, 56:3. 5. Nurse, R.E. and A. DiTommaso. 2003. Influence of seed pretreatment with sodium hypochlorite on seed germination and radicle elongation in three annual weed species. Proceedings of the 57th Annual Meeting of the Northeastern Weed Science Society of America, 57:123. 6. Reberg-Horton, C., N. Creamer, J. Burton, N. Ranells, and C. Mohler. 2001. Bioassay and field evaluation of rye cultivars for allelopathy. WSSA Abstracts, 2001 Meeting of the Weed Science Society of America 41:109-110 (No. 274). 7. Reberg-Horton, C., N. G. Creamer and C. L. Mohler. 2000. The suppression of weeds by nine varieties of rye (Secale cereale). WSSA Abstracts, 2000 Meeting of the Weed Science Society of America 40:27-28, (No. 66). 8. Teasdale, J. R. and C. L. Mohler. 2000. The physical properties of mulches contributing to weed suppression. Third International Weed Science Congress, Foz do Iguassu, Brazil, June 6 to 11, 2000, Abstracts, pp. 95-96 (No. 204). Thesis: 1. Brainard, D. C. 2002. Weed management implications of a broccoli-winter rye intercropping system. Ph.D. Dissertation, Cornell University Press, Ithaca, NY 14853, 136pp.

Impact Statements

Rye varieties may be selected for optimum weed suppression

Date of Annual Report: 04/17/2006

Report Information

Annual Meeting Dates: 02/13/2006 - 02/13/2006
Period the Report Covers: 01/01/2005 - 12/01/2005

Participants

Robin Bellinder, NY; Toni DiTommaso, NY;
Russ Hahn, NY; Chuck Mohler, NY;
John Teasdale, ARS-Beltsville; Dan Brainard, NY;
Jim Parochetti, CSREES; Mark VanGessel, DE

Brief Summary of Minutes

1. Introductions
The following individuals were present and introductions were made:

Robin Bellinder, NY Toni DiTommaso, NY
Russ Hahn, NY Chuck Mohler, NY
John Teasdale, ARS-Beltsville Dan Brainard, NY
Jim Parochetti, CSREES Mark VanGessel, DE

2. Elect secretary for 2006 (to become chairperson 2007)
Chuck Mohler, NY, agreed to serve as Secretary for 2006. Responsibilities of the Secretary include (A) recording Minutes of the annual meeting and (B) submission of the Minutes from the Annual Meeting to the Chairperson one month from the date of the meeting.

3. Approval of minutes of last years meeting. We neglected to do this.

4. Report from Administrative Advisor (Dr. William Vinson, WV)
Dr. Vinson was unable to attend the meeting.

5. Report from CSREES Liaison Member, Dr. Jim Parochetti
Jim reported that the Presidents 2007 budget includes substantial changes to Hatch funds, including regional projects. Under the proposed budget, 44.4% of Hatch funds would be distributed to states according to the formula. The remaining 55.6% of funds would be used for MultiState projects (up from the current 25% of Hatch funds). However, these MultiState funds would be distributed through a competitive grants program rather than through the experiment stations as is currently done. Projects would meet federally identified needs and would be both mult-state and multi-disciplinary. Projects already approved by the time the budget is adopted would, in theory at least, not be affected, and our new project may well be approved before the budget. Also, the change in the way Hatch funds are handled may not be approved by Congress this year, though Jim seemed to feel that some change along these lines was likely eventually. The report generated considerable discussion.

6. Meeting location and format for next year. We did not choose a meeting location for next year. Based on the poll taken last year regarding whether to meet in conjunction with WSSA or NEWSS, it seems likely that we will meet in conjunction with WSSA, but we will need to decide that.

7. Research Presentations
Project Reports from the following participants were presented, reviewed, and discussed:

1. R. Bellinder, Cornell University
2. C. Mohler, Cornell University
3. D. Brainard, Cornell, University
4. R. Hahn, Cornell University

8. Future Directions

Because so few people involved in the new project from outside NY were in attendance, discussion of objectives and procedures for that project was postponed. Dan Brainard and Chuck Mohler will complete revision of the proposal based on reviewers comments and circulate that within the next two weeks.

Meeting concluded at 4:30 pm, Mon. Feb. 13, 2006.

Accomplishments

Objective 2: Effects of mulch on soil moisture and weed emergence. In NY, a procedure was developed to examine effects of soil moisture on seed germination. Field soil was equilibrated to -10, -100, -300, -500 or -1000 kPa using a pressure plate. Prepared soil in Petri dishes was sown with weed seeds, covered with soil, and germination compared with seeds in PEG solutions. Petri dishes were sealed or left open and placed in a germination cabinet at 100% relative humidity. Constant weight of soil showed no moisture loss or gain in open dishes. PEG overestimated germination relative to closed dishes for Powell amaranth and common lambsquarters at intermediate soil moisture potentials, but underestimated germination for those species at -1000 kPa. Open dishes had lower germination than closed dishes at -300 or -500 kPa for Powell amaranth, velvetleaf and giant foxtail, even though moisture loss or gain was negligible in both treatments. Objective 4: Weed management in crop rotation. In NY, a manual on crop rotation planning was reviewed and revision was begun. Also in NY, a vegetable crop rotation x weed management intensity field trial was continued into the 4th of 5 years with the following crops in production this year: sweet corn, beet, cabbage and potatoes. In the spring, crop rotations involving continuous sweet corn had lower weed seed bank densities than those involving cabbage. Crop rotations involving cultivation without herbicides (0x) had almost 3 times the weed seed bank as those involving broadcast (1x) or banded herbicides (1/3X). Yields of beets were significantly reduced under 0 x treatments. Hairy galinsoga (Galinsoga ciliata) was the dominant weed species, accounting for greater than 50% of all seeds in all crop rotations. Galinsoga, pigweed, and lambsquarters densities were over three times greater in 0x treatments compared to 1/3x and 1x treatments; whereas there were no significant differences in grass species densities. In 2006, beans will be grown in all crop rotation treatments, allowing assessment of crop rotation and historic weed management intensity on crop yields. In Maine, a cropping systems study was continued, comparing no cover cropping in two year rotation of broccoli and winter squash, to fall cover cropping, a two-year red clover cover crop followed by the cash crops, and short duration cover cropping with periods of summer fallowing in alternate years with cover crops. Soil quality improved by cover cropping, as evidenced by decreases in bulk density and increases in water holding capacity, water stable aggregates, and particulate organic matter in select cover-cropping systems. Similar benefits of a preceding red clover cover crop were noted when the above ground biomass was removed prior to incorporation, indicating important contributions from the below ground biomass and opening up many questions regarding the role of roots in sustainable cropping systems. Despite an overall decline in the total weed seed bank in three of the four systems over the four years, common lambsquarters, a particularly pernicious species in most northeast cropping systems, increased in each of the systems. However, compared to a system without cover crops, common lambsquarters increased only slightly in the disturbance-intensive, alternate year cover crop system. The perennial cover crop system, despite an abundance of invertebrate seed predators, experienced no net reduction in the germinable weed seedbank over the four-year period. Abundant weed seed rain in the winter squash, as well as within select cover crops, prevented greater progress in depleting the weed seedbank in these cover cropping systems, and suggests that fall weed seed rain management should be carefully considered as part of a comprehensive weed seedbank management plan. Cover crop-based weed management systems appear to attract and retain significantly greater numbers of Maines dominant invertebrate weed seed predator, the ground beetle Harpalus rufipes. We decided to focus most of our work on H. rufipes, as it was the most abundant species throughout the duration of our research. On average, background H. rufipes populations were three times higher in fields planted with a pea-oat cover crop than in fallow fields. Pea-oat fields acted as refuges for beetles released in fallow fields. Within one week, greater than half of all beetles released in fallow fields moved into pea-oat fields. Over 90% of beetles released in pea-oat fields did not move into other fields. This finding supports the use of vegetated refuges as a way to preserve H. rufipes during periods of intense disturbance. In contrast, the presence or absence of a cover crop did not affect the abundance of H. rufipes adults emerging from pupation in the soil during June and July. This suggests that other factors are responsible for determining where immature H. rufipes develop. We also 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. We will also evaluate other differences amongst the systems (weed density, aboveground biomass, temperature, humidity, etc.) that may have also contributed to higher H. rufipes populations in the pea-oat/rye-vetch rotation. The impact of disturbance independent of cover cropping is currently under investigation at both Rogers and Aroostook Farms. Adult H. rufipes density is measured following disturbance (chisel plow, moldboard plow, or rototillage) versus an undisturbed control. No significant differences have been detected between control and disturbance treatments, though higher adult densities have been observed in the chisel plowed and rototilled plots. Furthermore, greater numbers of adults emerging from pupation have been noted in the control plots versus the three disturbances combined. This observation suggests that the softer-bodied newly emerged adults may be more sensitive to disturbance than the fully sclerotized adults. We will analyze this data further when this study concludes at the end of September 2005. New Objective 1. Reducing rates of natural product herbicides. Greenhouse trials were initiated to test the effects of acetic acid concentrations of 15, 20 (WeedWorks product), 25, and 30% on common lambsquarters (Chenopodium album L.), velvetleaf (Abutilon theophrasti Medic.), and powell amaranth (Amaranthus powellii S.) at the cotyledon, 2-, and 4-leaf stages. Applications were made at 34 and 68 gallons per acre (GPA). All treatments included yucca extract at 0.1% dilution, and each treatment was replicated 4 times. An additional trial evaluated the recommended and 2X recommended rates of three organically approved adjuvants, NaturL Oil (0.2, 0.4%), Yucca extract (0.1, 0.2%), and Humasol (2.5, 5%), when added to 20% acetic acid at 34 GPA. Velvetleaf proved least susceptible to injury compared to powell amaranth and common lambsquarters. Survival rates increased with increasing weed size for all weed species, particularly once the weeds were at the 4-leaf stage. Fifteen percent acetic acid applied at 34GPA was often not effective beyond the cotyledon stage; although 15% acetic acid applied at 68 GPA provided consistently better control. With the addition of selected adjuvants to 20% acetic acid at 34 GPA, there was some improvement in control of velvetleaf, lambsquarters, and pigweed. New Objective 2. Effects of cover crop planting date and method of incorporation on weed suppression A trial was initiated to examine the effects of (i) buckwheat cover crops on in-season weed growth, and (ii) buckwheat residue on emergence and growth of weeds in a subsequent wheat crop. In-season weed suppression by buckwheat in the field ranged from 97-99%. Freshly incorporated buckwheat residue suppressed emergence and growth of wheat as well as 7 out of 8 weed species. The most sensitive species were Powell amaranth, corn chamomile and shepherds purse. Several experiments were initiated to assess possible mechanisms of suppression. Initial results suggest that buckwheat residue interactions with nitrogen availability and fungal pathogens play a significant role in the suppression by buckwheat residue of certain weed species. New Objective 3. Effects of soil nutrients on crop-weed competition and weed management. An experiment examining effects of gypsum amendment on weeds was begun for the proposed new Multi-state project. Gypsum was applied at 480 lb/a or not to 40 by 60 plots in a randomized block design. Organically managed soybeans did not differ in yield (43 bu/a), weed density (38 /m sq), or weed biomass (20 g/sq m). The experiment will be continued on the same plots.

Publications

Brainard, D. C., A. DiTommaso and C. L. Mohler. 2005 Ecotypic variation in seedcharacteristics of Powell amaranth from habitats with contrasting crop rotation histories. Proceedings of the 59th Annual Meeting of the Northeastern Weed Science Society 59:142. Gallandt, E. R. 2005. Experimental substrate affects rate of seed removal in assays of invertebrate seed predation. Weed Technology 19:481-485. Gallandt, E. R., T. Molloy, R. P. Lynch, and F. A. Drummond. 2005. Effect of cover cropping systems on invertebrate seed predation. Weed Science 53:69-76. Haramoto, E. R., and E. R. Gallandt. 2005. Brassica cover cropping: I. Effects on weed and crop establishment. Weed Science 53:695-701. Haramoto, E. R., and E. R. Gallandt. 2005. Brassica cover cropping: II. Effects on growth and interference of green bean and redroot pigweed. Weed Science 53:702-708. Mohler, C. L., J. C. Frisch and C. E. McCulloch. 2006. Vertical movement of weed seed surrogates by tillage implements and natural processes. Soil and Tillage Research, in press. Mohler, C. L. 2005, Weeds and weed management on eleven northeastern organic farms. Proceedings of the 59th Annual Meeting of the Northeastern Weed Science Society 59:141. Shearin, A. and S.C. Reberg-Horton. 2005. Cover crop management impacts on the weed seed predator Harpalus rufipes. Proceedings of the Annual Meeting Northeastern Weed Science Society 59: 77. Shearin, A. F., S.C. Reberg-Horton, E.R. Gallandt, and F.A. Drummond. 2005. Cover crop and cultivation impacts on the weed seed predator Harpalus rufipes. Programs and Abstracts of the Annual Meeting American Society for Horticultural Science. Hortscience 40(1): 1102.

Impact Statements

Better understanding of the effects of soil moisture on weed seed germination will improve our ability to model germination processes in field conditions. This will allow improved advice to growers as to the conditions under which weed management practices like blind cultivation and use of pre-emergence herbicides are likely to fail. It will also improve recommendations on the timing of weed management practices.
Planning good crop rotations is difficult, particularly for organic producers and diversified vegetable growers. The manual will provide information and a planning procedure for facilitating development of good rotations, even in complex situations. The vegetable crop rotation studies should facilitate better understanding of shifts in species density and composition resulting from different crop rotations and intensities of weed management. Information from these study will help growers plan their crop rotation sequences, and better understand the long-term consequences of their weed and soil management strategies.
Information on natural product herbicides should be helpful for providing another tool for organic growers to improve weed management while minimizing soil disturbance. Improved understanding of the effects of adjuvants and rates on specific weed species should also reduce the costs of natural product herbicides and make them an affordable option for organic growers.
Information from buckwheat studies should facilitate management of weeds while improving soil quality, reducing reliance on tillage and cultivation, and improving crop yields.
Many organic growers believe that application of gypsum improves weed management. Determining whether this is the case will either improve weed management on farms not using gypsum or reduce input costs on farms that do use it.