Strategies for managing the weed seedbank and encouraging weed seed predation

Transcription

1 Strategies for managing the weed seedbank and encouraging weed seed predation Adam Davis USDA-ARS Global Change and Photosynthesis Research Unit Urbana, IL

2 weed seedbank Artwork: Cherie Earle

3 Artwork: Steve Deming

4 1. How prevalent is weed seed return? 2. Does it matter? 3. What can we do about it?

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10 Seed population density (seeds m -2 ) CONV AMARE CHEAL GRASS OTHER Time (yr) d ȮRG

11 Survey: weed seeds at harvest time 1. undispersed, standing 2. on soil surface 16 fields (8 corn, 8 sb) 30 samples/field 3. in soil seedbank 4. caught by combine

12 giant foxtail redroot pigweed velvetleaf Seeds m combine soil standing Seed pool surface combine soil standing Seed pool surface combine soil standing Seed pool surface 26 species total Davis 2008

13 Weed seedbank is persistent Years required for X % reduction in seed number 50% Common lambsquarters 12 Velvetleaf 8 Common chickweed 3 Smartweed 4 Redroot pigweed 4 Common ragweed 2.5 Crabgrass, giant foxtail < 1 Kochia < 1

14 Weed seedbank is persistent Years required for X % reduction in seed number 50% 99% Common lambsquarters Velvetleaf 8 56 Common chickweed 3 18 Smartweed 4 30 Redroot pigweed 4 26 Common ragweed Crabgrass, giant foxtail < 1 6 Kochia < 1 6

15 velvetleaf Seed germination (%) _ Burial time (yr) LOCATION Lincoln Scottsbluff Burnside et al. 1996

16 redroot pigweed 80 Seed germination (%) Burial time (yr) LOCATION Lincoln Scottsbluff Burnside et al. 1996

17 Why should we manage the weed seedbank?

18 Economic submodel control cost lost crop revenue Demographic sub-model seeds g small seedlings s cult large seedlings s s (1-g) f*s pred mature plants s hand Liebman and Davis (2009)

19 Physical control efficacy Handweeding efficacy Seedbank decline Seed predation 350 Cost ($/ha) in 5th yr = base value in model = realistic parameter range Lower level parameter x Liebman and Davis (2009)

20 DIAS Hand weeding intra-row weeds: hours per hectare in carrot and direct sown onion and leek Melander and Rasmussen, 2001

21 Relationship between weed density and time consumption for hand weeding DIAS Time hand-weeding (h ha -1 ) Intra-row weed number (m -2 ) Melander and Rasmussen, 2001

22 Do seed escapes matter? Davis and Williams Weed Sci. 55:

23 Yes. Wild proso millet fecundity in sweet corn had effects on following snap bean crop Rec ME Rec ME Fec Y Fec Y Pop CE Pop CE Davis and Williams Weed Sci. 55:

24 Ecological management of weed seedbanks cultural physical biological

25 Biological: I. Seed survival in soil seedbank intact decayed Chee-Sanford et al. (2006)

26 80 giant foxtail velvetleaf Weed seed mortality (%) y = x R 2 =0.27, P<0.05 y = x R 2 =0.29, P< Fungal 18S principal component 1 organic 3-yr rotation conventional 3-yr rotation old field conventional 4-yr rotation reduced input 4-yr rotation Davis et al. (2006)

27 Davis et al Weed Sci. 56:

28 Biological: II. Seed predation Photo: Adam Davis

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30 Common predators of weed seeds. We need more of these in our cropping systems!

31 Daily % seed removal * * * ** NS Wheat Wheat + red clover 9-Aug 29-Aug 18-Sep 8-Oct Seed recovery date Davis et al. (2003)

32 Annual rate of seed predation in field crops Urbana, IL

33 Weed seed predation over time (giant foxtail) % Seed loss to predation DAYS_ELAPSED CROP_05 corn soybean wheat/red cl

34 Weed seed predation over time (giant ragweed) % Seed loss to predation DAYS_ELAPSED CROP_05 corn soybean wheat/red cl

35 Can we maintain high seed predation rates throughout year by diversifying crops? 100 Seed predation (%) 50? 0 spring summer autumn winter corn, soybean small grain + legume alfalfa after Heggenstaller et al. (2006)

36 1.0 P(seed predation) Day of Year

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39 Lundgren et al. 2007

40 beetle banks

41 Cultural: I. Cover crops and mulches

42 Cultural: II. Weed suppressive crop cultivars crop yield loss: weed seeds: Williams et al. 2008

43 Cultural: III. Crop population and spatial arrangement

44 Cultural: IV. Crop rotation and diversification Schreiber 1992

45 Physical: I. Improved intrarow control efficacy to reduce hand-weeding costs Band-steaming reduced intra-row weeds in sugar beet Melander & Jørgensen 2005

46 More physical and thermal tools: intrarow

47 Physical: II. Tillage as one-time rescue for massive seed input Photo: Adam Davis

48 Percentage of seeds at depth Depth (inches) moldboard plow chisel plow rototiller disk no-till Mohler (2001)

49 Physical: III. Stale seedbed Physicalweeding.com

50 Physical: IV. Weed seed collection at harvest

51 Bibliography Davis, A. S., K. A. Renner, C. Sprague, L. Dyer and D. Mutch Integrated weed management...one year's seeding. Michigan State University Extension Bulletin E Pp Hartzler, R. G. and D. D. Buhler Weed seeds and the seedbank: implications for management. Iowa State University. IPM-48. Pp Menalled, F., J. Dauer, T. Fox and K. Renner Managing your farm to increase weed seed predation. Michigan State University. E Pp Menalled, F. D., M. Liebman and K. Renner The ecology of weed seed predation in herbaceous crop systems. ed. Pp H. P. Singh, D. R. Batish and R. K. Kohli.) Binghamton, NY: Haworth Press. *Scientific literature mentioned in presentation available upon request (contact Adam Davis: ) or John Masiunas: )