Invasive Weeds & Endangered Species Interactions: Can Herbicides Facilitate a Positive Outcome?

Transcription

1 Invasive Weeds & Endangered Species Interactions: Can Herbicides Facilitate a Positive Outcome? George Beck, Scott Nissen & Jim Sebastian Dept Bioag Sciences & Pest Mgmt Colorado State University

2 Broadleaf Herbicides & Desirable Forbs Are buffer zones always biologically necessary around threatened or endangered species? Selectively controlling weedy forbs among desirable forbs Difficult with many older herbicides 2,4-D, dicamba Particularly high rates needed to control many invasive perennial weeds Research has shown selectivity does not just occur between grasses and forbs Also within forbs

3 Broadleaf Herbicides & Desirable Forbs Rice, P.M. J.C. Toney, D.J. Bedunah, & C.E. Carlson Plant community diversity and growth form responses to herbicide applications for control of Centaurea maculosa. J. Applied Ecol. 34(6): Treated spotted knapweed infested grassland and early seral forest Sprayed 1989; plots split and one-half retreated 1992 Picloram (280 g/ha), clopyralid (280 g/ha), clopyralid + 2,4-D ( g/ha) Early v. late season applications

4 Broadleaf Herbicides & Desirable Forbs Rice et al. 1997: Cover, standing crop, species richness: Grasses increased 1 to 2 yr post treatment then leveled to same as untreated plots Forbs declined 1 to 2 yr post treatment then increased to same as untreated plots Early season spraying caused greater forb decrease and grass increase than late season spraying

5 Western fringed prairie orchid; Platanthera praeclara

6 Leafy Spurge Control Near the Western Prairie Fringed Orchid Western prairie fringed orchid Platanthera praeclara Federally listed threatened species Leafy spurge encroaching into WPFO habitat Competition from leafy spurge threatens orchid survival Sieg, C.H. & A.J. Bjugstad Proc. 13 th N.American Prairie Conf. p USFWS Platanthera praeclara recovery plan. Wolken et al J. Range Manage. 54:

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8 Leafy Spurge Control Near the Western Prairie Fringed Orchid Erickson et al. 2006: Sprayed quinclorac (Paramount) or imazapic (Plateau) directly onto western fringed prairie orchid September when senescing Quniclorac 842 & 1121 g ai/ha Imazapic 140 & 210 g ai/ha At 10 & 22 months after application measured Survival & fecundity of orchids Whether remained vegetative or flowered; Plant height Number of flowers & seed production

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10 Leafy Spurge Control Near the Western Prairie Fringed Orchid Neither imazpic or quinclorac influenced orchid survival imazapic caused stunting, decreased flower & seed production

11 Percent Herbicide Effects on Western Prairie Orchid Flowering 10 MAT ab b a a ab ns a a b b b ns Imaz 140g Imaz 210g Quin 842g Quin 1121g 0 Flowering 2000 Flowering 2001 Vege 2000 Vege 2001 Untreated

12 Herbicide Effects Western Prairie Orchid Flowering 22 MAT No differences among treatments 2 nd year after spraying All effects on flowering by imazapic disappeared 2 years after initial treatments applied

13 Herbicide Effects on Western Prairie Flower Height, Raceme Length, and Flower Number Quniclorac had no effect WPFO height, raceme length & flower number 10 and 22 MAT Imazapic decreased WPFO height by ~43% at 140 & 210 g/ha 10 MAT Effect disappeared 22 MAT Imazapic decreased WPFO raceme length ~78% 10 MAT; 58% 22 MAT at 210 g/ha Imazapic decreased WPFO flower number by ~73% 10 MAT 70% 22 MAT at 210 g/ha

14 Number seeds per capsule Herbicide Effects on Western Prairie Orchid Seed Set 12 MAT a a Imaz 140g % 7% Imaz 210g Quin 842g b b Quin 1121g Untreated % b 0% 0%

15 Herbicide Effects WPFO Conclusions Quinclorac safe to use if WPFO present when controlling leafy spurge Imazapic caused temporary stunting and decreased fecundity WPFO Most symptoms disappeared 2 nd year following treatment

16 Russian Knapweed Control & Native Forb & Shrub Establishment Experiment established May, 2009 Strip-strip plot four replications; P= herbicide treatments Aminopyralid at 126 g ai ha -1 Untreated control 16 native seeded species 10 forbs 4 shrubs 2 cool season perennial grasses Herbicides applied May 14, 2009 Native species seeded April 2010

17 Gayfeather Liatris punctata Common yarrow Achillea millifolium Penstemon spp.

18 Common yarrow Achillea millifolium

19 Gayfeather Liatris punctata

20 One-sided Penstemon Penstemon secundiflorus

21 Russian Knapweed Control & Native Forb Establishment Plants/m a a a b a b a a Amino 126 g ai/ha Untreated Data fall 2010; compare within species RK control: mean aminopyralid=71%; untreated=0%

22 Louisiana sage

23 Louisiana sage Artemisia ludoviciana

24 Fourwing saltbush; Atriplex canescens

25 Fourwing saltbush Atriplex canescens

26 Winterfat; Krascheninnikovia lanata

27 Winterfat Krascheninnikovia lanata

28 Russian Knapweed Control & Native Shrub Establishment 10 9 a 8 Plants/m a a Amino 126 g ai/ha Untreated 2 1 a 0 a Louisiana sage a Winterfat a Fourwing saltbush a Mean shrubs Data fall 2010; compare within species RK control: mean aminopyralid=71%; untreated=0%

29 RK Control & Native Forb & Shrub Establishment Summary Species richness is the number of species in a given area (% species established in area): untreated controls: Forbs 8%; shrubs 0%, grasses 50% Aminopyralid 126 g ha -1 71% Russian knapweed control Forbs 63%; shrubs 56%; grasses 100%

30 Aminopyralid Effects Established Native Forbs & Shrubs Two Experiments initiated summer 2009 Steamboat Springs, CO 3 Timings July 10; Sep 4; Oct 16 3 rates aminopyralid 53 g ha -1 + non-ionic surfactant (0.25% v/v) 126 g ha -1 + non-ionic surfactant (0.25% v/v) 126 g ha -1

31 Western indian paintbrush Castilleja occidentalis

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33 Western Indian Paintbrush Castilleja occidentalis

34 Five nerve sunflower Helianthella quinquenerva

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36 Five nerve sunflower Helianthella quinquenerva

37 # species per plot Aminopyralid Effects Total Species Richness ns a a 53 g nis Jul 126 g nis Jul 126 g Jul 53 g nis Sep 126 g nis Sep g Sep g nis Oct 126 g nis Oct 126 g Oct Untreated

38 Native Forb and Shrub Tolerance to Aminopyralid (Milestone Herbicide) Applications for Invasive Weed Control Mary B. Halstvedt* and Vanelle F. Peterson, Dow AgroSciences LLC., Billings, MT and Mulino, OR; Travis Almquist, Luke Samuel, Rodney G Lym, North Dakota State University, Fargo; K. George Beck, Colorado State University, Ft. Collins; Roger L. Becker, University of Minnesota, St. Paul; Celestine A. Duncan, Weed Management Services, Helena, MT; Peter M. Rice, University of Montana, Missoula. Trademark of Dow AgroSciences LLC

39 Experiments Established at 10 Locations Celestine Duncan, Weed Management Services Rod Lym, North Dakota State University Peter Rice, University of Montana Roger Becker, University of Minnesota George Beck, Colorado State University

40 Four Ranking Catagories T=Tolerant: Minimal symptoms - may be slight cupping but less than 15% MT = Moderately tolerant: Symptoms include cupping/yellowing and can inhibit flowering, with recovery the first growing season after application 15-50% stand reduction MS = Moderately Susceptible: Injury could be significant the first year may reduce stand by 50-75% S = Susceptible: Severe Injury the season of application and stand reduction the year after greater than 75% - and may kill established plants. However, certain plants may reseed from the seed bank.

41 Results of 68 Forbs Evaluated 2 YAT Significant recovery Tolerant M Tol MS Suceptible Tolerant M Tol MS Suceptible 1 YAT 2 YAT

42 Milestone Transline Tordon 22k Garlon 3a Vanquish 2,4-D amine 2,4-D LV4 Paramount Telar XP Escort XP Plateau Curtail Redeem R&P Grazon P&D Overdrive Cim Max Check Conclusion Robust Spurge Woods Rose Penstemon Blue Flax Gay feather *Data subjected to analysis of variance and means separated by Tukey s HSD (α=0.05) *Different colors signify statistical differences between counts in control v treated plots. *Green signifies an increase in the population, white no change and red a decrease.

43 Overall Conclusion Herbicides an important part of ecologically-based weed mgmt Newer herbicides more selective than older ones & effects are transient Exercise care to choose compounds will control target without permanent injury to desirable forb, shrubs, & grasses Continue to evaluate against native forbs & shrubs Spray buffers may not be generally necessary Evaluate case by case using sound applied science Buffers continuous source of invasive weeds Ultimately an invasive weed will displace T&E plant species