Current options – Chemical control of grassy weeds in range and pasture Gillette, WY - January 20, 2012
Brian A. Mealor Assistant Professor and Extension Weed Specialist
Bulbous bluegrass
Cheatgrass
Foxtail barley
Levels of management Strategy • A clear goal is defined • A path to the goal is envisioned • Limitations/challenges are discussed • Organization
Tactics • Tools for specific tasks or objectives • Steps within the path are appropriately implemented • Implementation
The best weed management tool
Overview • Herbicides labeled for control of grassy weeds in R&P • Considerations when using chemical control • What can we expect if using herbicide to manage these weedy species?
Why control grassy weeds? • Increase species diversity • Improve forage base • Protect desirable plant community – Reduce probability of altered fire regime – Big sagebrush not tolerant of fire
• Secondary invaders adapted to frequent disturbance events
Management principles 1. Prevention should be a priority 2. Correctly identify the target weed species 3. Understand the distribution of the weed 4. Evaluate current status (recovery potential) 5. Select a method of control suited for your situation 6. Implement 7. Evaluate your results 8. Continue to monitor and follow up
AGGRESSIVE MANAGEMENT?
Maintenance / prevention
Eradication of source populations
Long-term management
Restoration / Abandonment
• Density and size of invasion will also inform management strategy
SIZE Small
DENSITY
Large
Low
Monitor infestations; may need a change in management or may pull by hand
Monitor; grazing practices; monitor or manage escape routes
High
Eradicate spots; continue to monitor closely; promote sustainability of native vegetation (change in management)
Integrated weed management; restoration efforts
DESIRABLES
WEEDS
Cheatgrass management mindset Control cheatgrass long enough to allow perennial plants to recover/establish/grow (etc.) in hopes that perennial competition will reduce cheatgrass over the long-term
Can I use herbicides to control grassy weeds without killing other grasses?
Which herbicides are available to manage for these weeds in range and pasture?
Glyphosate (Roundup©) • Can be applied at low rates in early spring for suppression • Take care to apply when desirable vegetation is dormant to reduce injury • Can be used in re-seeding projects • 10-20 oz product per acre • ~ < $1 / oz
Imazapic (Plateau, Panoramic) • Pre- or post emergent (2-12 oz product / acre) – 4-8 oz pre-emergent in fall
• • • •
Maintain residual desirable plants No grazing restrictions Can re-seed following application Chemical needs to reach soil surface (litter will inhibit activity) for pre-emergent treatments • Split- applications in spring/summer suppress foxtail barley (Violett and Whitson, unpublished) • Sagebrush species display high tolerance at labeled rates • ~ $3 / oz
6 oz/a Plateau applied Oct. 6 2010
Imazapic + Glyphosate (Journey©) • Provides both pre- and postemergent control • Fall is ideal, spring applications can also be used • Spring – be careful with desirable plants • 16-32 oz product per acre • ~ $ 1.25 / oz
Rimsulfuron (Matrix ©) • Labeled for restoration of rangelands degraded by annual grass invasion • Fall applied pre-emergence activity at ~1-3 oz product / acre • Relatively safe on desirable species, longer replant interval • Low rates, but very high efficacy on cheatgrass and other annual grasses (i.e. medusahead), foxtail barley • ~$17 / ounce
Cheatgrass biomass production (growth)
Fall pre-emergent application Lingle, WY.
Propoxycarbazone (Canter R+P©) • Newly labeled rangeland product • Effective both pre-emergent and early postemergent • Somewhat active on foxtail barley as well • Early applications related to better control • 0.9-1.2 oz product per acre
1025-1113 C Utah State University â&#x20AC;&#x201C; Corey Ransom Foxtail Barley Control (97 DAT)
Untreated
Canter R & P (0.9 oz/acre) + Climb (2 oz/gal) + Super Spread MSO (1 qt/acre)
Canter R & P (1.2 oz/acre) + Climb (2 oz/gal) + Super Spread MSO (1 qt/acre)
Milestone (7 oz/acre)
0
10
Thank you: Corey Ransom and Dewayne Harper
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50 60 Percent Control
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Carbon County, Wyoming Foxtail Barley Control (47 DAT) Spring application
untreated check
Canter R+P 1.2 oz MSO 1 qt/a
Canter R+P 0.9 oz MSO 1 qt/a
Plateau 8 oz NIS 0.25 %
0
10
20
30
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50 60 Percent Control
70
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Sbatella et al. 2011
Sulfometuron + Chlorsulfuron (Landmark XP©) • Labeled for rangeland restoration • Effective both pre-emergent and early postemergent • Only range and pasture product with bulbous bluegrass specifically listed on the label • .75-1.5 oz product per acre
If I remove these weeds, will I have more good grasses?
It depends • Are desirable species still living in the cheatgrass? • If not, you may have to seed desirable species
Where high levels of cheatgrass control is achieved, and sufficient perennial grasses are on-site: Non-cheatgrass perennial forage can increase 200% or more (multiple Wyoming studies).
How might I predict recovery potential of the site?
What factors might affect my success?
Concerns • What type of return on investment (treatment cost) is needed? • How many years of control can we expect from a single treatment? • Can we permanently remove target weeds from our property?
Wrapup • Many options exist • Match the control strategy to the situation – More on that soon
• If perennial plants still exist in the system, the chance of recovery should be high • Cheatgrass-resistant native communities may not be possible
Brian A. Mealor
bamealor@uwyo.edu
307-766-3113
1. I have foxtail barley in my horse pasture and I have to feed more hay each year to keep my horse in good condition. There is a lot of foxtail barley, but there are still good grasses underneath it. What should I do?
2. I purchased a property which was farmed in the past and it is completely dominated by cheatgrass. I would like to have less cheatgrass and more desirable species. Any ideas?
3. I manage an allotment where there was a large wildfire this year. I would like to prevent cheatgrass from increasing. Only a small portion of the allotment had cheatgrass before the fire. What is the best approach to take?
4. I am beginning to see small patches of bulbous bluegrass on my ranch near some prairie dog holes, but I am not worried about it now. Do you think it will become a problem?