Current options – Chemicalcontrol of grassy weeds in

range and pastureGillette, WY - January 20, 2012

Brian A. Mealor

Assistant Professor and

Extension Weed Specialist

Bulbousbluegrass Foxtail

barley

Cheatgrass

barley

Levels of management

Strategy

• A clear goal is defined

• A path to the goal isenvisioned

Tactics

• Tools for specific tasks orobjectives

• Steps within the path areappropriately• Limitations/challenges

are discussed

• Organization

appropriatelyimplemented

• Implementation

The best weed management tool

Overview

• Herbicides labeled for control of grassyweeds in R&P

• Considerations when using chemicalcontrolcontrol

• What can we expect if using herbicide tomanage these weedy species?

Why control grassy weeds?

• Increase species diversity

• Improve forage base

• Protect desirable plant community

– Reduce probability of altered fire regime– Reduce probability of altered fire regime

– Big sagebrush not tolerant of fire

• Secondary invaders adapted to frequentdisturbance 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)4. Evaluate current status (recovery potential)

5. Select a method of control suited for yoursituation

6. Implement

7. Evaluate your results

8. Continue to monitor and follow up

Restoration /Abandonment

Long-termmanagement

Eradication ofsource populations

Maintenance /prevention

AGGRESSIVEMANAGEMENT?

• Density and size of invasion will also informmanagement strategy

SIZE

Small LargeSmall Large

DENSITY

Low Monitor infestations; mayneed a change in managementor may pull by hand

Monitor; grazing practices;monitor or manage escaperoutes

High Eradicate spots; continue tomonitor closely; promotesustainability of nativevegetation (change inmanagement)

Integrated weed management;restoration efforts

DESIRABLESDESIRABLES

WEEDSWEEDS

DESIRABLESDESIRABLES

Cheatgrass managementmindset

Control cheatgrass long enough toallow perennial plants toallow perennial plants torecover/establish/grow (etc.) in hopesthat perennial competition will reducecheatgrass over the long-term

Can I use herbicides to controlgrassy weeds without killing

other grasses?other grasses?

Which herbicides are availableto manage for these weeds in

range and pasture?range and pasture?

Glyphosate (Roundup©)

• Can be applied at low rates in early spring forsuppression

• Take care to apply when desirable vegetationis dormant to reduce injuryis 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 beused

• Spring – be careful with desirable plants• 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 ozproduct / acre

• Relatively safe on desirable species, longer• Relatively safe on desirable species, longerreplant interval

• Low rates, but very high efficacy on cheatgrassand 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 post-emergent

• Somewhat active on foxtail barley as well• Somewhat active on foxtail barley as well

• Early applications related to better control

• 0.9-1.2 oz product per acre

Canter R & P (0.9 oz/acre)+ Climb (2 oz/gal)

+ Super Spread MSO (1 qt/acre)

Untreated

1025-1113 CUtah State University – Corey Ransom

Foxtail Barley Control (97 DAT)

0 10 20 30 40 50 60 70 80 90 100

Milestone (7 oz/acre)

Canter R & P (1.2 oz/acre)+ Climb (2 oz/gal)

+ Super Spread MSO (1 qt/acre)

Percent Control

Thank you: Corey Ransom and Dewayne Harper

Carbon County, WyomingFoxtail Barley Control (47 DAT)

Spring application

untreated check

Canter R+P 1.2 ozMSO 1 qt/a

0 10 20 30 40 50 60 70 80 90 100

Percent Control

MSO 1 qt/a

Canter R+P 0.9 ozMSO 1 qt/a

Plateau 8 ozNIS 0.25 %

Sbatella et al. 2011

Sulfometuron + Chlorsulfuron(Landmark XP©)

• Labeled for rangeland restoration

• Effective both pre-emergent and early post-emergent

• Only range and pasture product with bulbous• Only range and pasture product with bulbousbluegrass specifically listed on the label

• .75-1.5 oz product per acre

If I remove these weeds, will Ihave more good grasses?have more good grasses?

It depends

• Are desirable species still living in thecheatgrass?

• If not, you may have to seed desirable• If not, you may have to seed desirablespecies

Where high levels of cheatgrasscontrol is achieved, and sufficientperennial grasses are on-site:

Non-cheatgrass perennial forage canNon-cheatgrass perennial forage canincrease 200% or more (multipleWyoming studies).

How might I predict recoverypotential of the site?potential of the site?

What factors might affect mysuccess?success?

Concerns

• What type of return on investment(treatment cost) is needed?

• How many years of control can we expectfrom a single treatment?from a single treatment?

• Can we permanently remove target weedsfrom 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,• If perennial plants still exist in the system,the chance of recovery should be high

• Cheatgrass-resistant native communitiesmay 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 eachyear to keep my horse in good condition. There is a lot of foxtail barley, butthere are still good grasses underneath it. What should I do?

2. I purchased a property which was farmed in the past and it is completelydominated by cheatgrass. I would like to have less cheatgrass and moredesirable species. Any ideas?

3. I manage an allotment where there was a large wildfire this year. I would3. I manage an allotment where there was a large wildfire this year. I wouldlike to prevent cheatgrass from increasing. Only a small portion of theallotment 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 nearsome prairie dog holes, but I am not worried about it now. Do you think it willbecome a problem?