Managing the weed seedbank

Transcription

1 Managing the weed seedbank Christian Willenborg 1, Sharavari Kulkarni 2, Lloyd Dosdall 2, John Spence 3 1 Department of Plant Sciences, University of Saskatchewan; 2 AFNS, University of Alberta; 3 Ren. Resources, University of Alberta

2 Outline What is the seedbank? Sources of seedbank inputs Considerations for managing the seedbank Control Methods Chaff Collection Seed Destructor Seed Predators

3 Fate of Seeds Germinate Dormant Die (aging) Die (predators)

4 Questions for management How prevalent is weed seed return? Does it matter? What can we do about it? management Photo: Cress seeds Photo: Breanne Tidemann

5 Seed Capacity/Production Van Acker and Bartlinski, 2006 Species Maximum Minimum Field Mean Quackgrass (seed) Volunteer wheat Foxtail barley Wild Oat Cleavers Wild buckwheat Volunteer canola Chickweed Canada Thistle (seed) Curled dock Wild mustard Dandelion G. Foxtail P. sowthistle (seed) Kochia Lamb s quarters Redroot pigweed Stinkweed Low Med High V. High

6 Seed bank Longevity does it matter? Species Maximum Minimum Practical Kochia 2 yrs 0 yr 0-2 yrs Volunteer wheat 3 yrs 0 yr 0-2 yrs Foxtail barley 7 yrs 1 yr 1-2 yrs Canada Thistle (roots) 2 yrs 1 yr 1-2 yrs Dandelion 2 yrs 1 yr 1-2 yrs Quackgrass (seed) 4 yrs 1 yr 1-3 yrs Cleavers 5 yrs 1 yr 1-3 yrs Annual sowthistle 5 yrs 1 yr 1-4 yrs Canada Thistle (seed) 21 yrs 1 yr 2-3 yrs Perennial sowthistle (seed) 5 yrs 2 yrs 2-5 yrs Volunteer canola 14 yrs 1 yr 3-5 yrs Wild Oat 7-9 yrs 3 yrs 4-5 yrs Chickweed 10 yrs 6 yrs 5-10 yrs Wild buckwheat >6yrs 6 yrs 6-10 yrs G. Foxtail 30 yrs 4-5 yrs 5-15 yrs Lamb s quarters 39 yrs 6-8 yrs 8-20 yrs Redroot pigweed 40 yrs 10 yrs yrs Stinkweed 30 yrs 8 yrs yrs Curled dock 80 yrs 10yrs yrs Short Med Long V. Long Van Acker and Bartlinski, 2006

7 Species Seed Longevity Seed Production Problem Rating Rating Rating Quackgrass (seed) L L 1 Volunteer wheat L L 1 Foxtail barley L L 1 Wild Oat M L 2 Cleavers L M 2 Canada Thistle (seed) M M 3 Kochia L H 3 Volunteer canola M M 3 Dandelion L H 3 P. sowthistle (seed) M H 4 Wild buckwheat H M 4 Chickweed H M 4 G. Foxtail H H 5 Curled dock VH H 6 Wild mustard VH H 6 Lamb s quarters H VH 6 Redroot pigweed VH VH 7 Stinkweed VH VH 7 V. Low L. Low Low Med M. High High V. High Van Acker and Bartlinski, 2006

8 Additional Considerations New weed? Tough to control weed? Herbicide Resistant? Dispersal?

9 Additional Considerations New weed? Tough to control weed? Herbicide Resistant? Dispersal? Seed burial?

10 Proportion seeds consumed Kulkarni et al. (2015) Seed burial depth (cm)

11 Davis (2008) Weed Sci.

12 Managing the seedbank Chaff collection Seed destructors Seed predators

13 Chaff management

14

15 Photos: Bart Lardner Grazing Crop Residues

16 Harrington Seed Destructor Tideman et al. (2017). Weed Sci. 65:

17 Concerns Cost? New silver bullet? Ultimately, weed seeds will still fall Weed biology Timing of seed shed? Height Weed Evolution? to ground! youtube

18 Cumulative seed shatter (%) Seed Shatter G.D.D (base 5 C) Burton et al. (2017).

19 Wildlife Solutions Seed Predators Xtension.org

20 % seed predation Seed Predators Seed predation can be responsible for up to 90% seed loss (Honek et al. (2005) Ground beetles and crickets greatest sources of loss in fields youtube Westerman et al. (2005). Weed Res.

21 Activity-density Outbreaks of Amara Floate and Spence (2015) b) Vegreville P. melanarius A. littoralis A.quenseli Amara spp. H.affinis Week Kulkarni et al. (2017). Ag. Ecosyst. Environ. Photo Courtesy: B. Berry

22 Seed Predators - carabids Site Parameters Index of Association X k Seedling density Seed density Leduc 2011 (Grid 1) Omnivorous Carabid Activity 0.56* 0.30 density Major species: P. melanarius 0.41* 0.25 Vegreville 2011 (Grid 2) Leduc 2012 (Grid 3) Omnivorous Carabid Activity 0.72* 0.23 density Major species: A. littoralis 0.70* 0.32 Omnivorous Carabid Activity 0.73* 0.42 density Major species: P. melanarius 0.71* 0.30 St. Albert 2012 Omnivorous Carabid Activity (Grid 4) density Major species 1: P. melanarius and A. littoralis *indicates significant association at P < * * 0.18 Kulkarni et al. (2017). Ag. Ecosyst. Environ.

23 Weed Species Seed Preferences Velvetleaf Giant Foxtail C Waterhemp A Lambsquarters B Seeds consumed (%) Van der Laat et al. (2015). Weed Science

24 Weed Species Seed Preferences T. Arevnse C S. Arvensis B B. Napus A Seed removal (% week -1 ) Kulkarni et al. (2016). Weed Science

25 Seed Preferences

26 Strategies to Enhance Seed Predation

27 Encouraging Seed Predators 1. Diversified Crop Rotations Iowa State Heggenstaller et al. (2006). J. Appl. Ecol.

28 Encouraging Seed Predators 2. Beetle Banks MacLeod et al. (2004). Agric Forest Entol.

29 Encouraging Seed Predators 3. Cover Crops Prairie Creek Seed

30 Seed Predators are prey Besgroup.org

31 Encouraging Seed Predators 4. Decrease Tillage Seed predators require: -food -water -overwintering habitat -shelter from adversity

32 Encouraging Seed Predators 5. Canopy Closure Row Spacing Spatial Arrangement

33 Acknowledgements