OREGON S TAT E UNI V ERSI T Y E X T ENSION SERV ICE

Fara Ann Brummer, Extension Sage Steppe Ecosystems Faculty Research Assistant, Lakeview County; Pete Schreder, Extension Agriculture and Rangeland Resources Specialist, Lakeview County, both of Oregon State University; Grace Haskins, Bureau of Land Management Weed Specialist, Lakeview, Oregon; and Jason Jaeger, Lake County Weed Management Area Coordinator, Lakeview, Oregon

RECOGNIZING AND IDENTIFYING

Three Invasive Annual Grasses in the Great Basin Desert

Downy Brome (Cheatgrass), Medusahead, and Ventenata

Invasive annual grasses are a threat to the Great Basin desert ecosystem. They compromise habitat diversity for important wildlife species such as the greater sage-grouse. They shorten the grazing season for livestock, and do not provide as much consistent forage biomass and quality as perennial native bunchgrasses. They tend to be much smaller, have less overall leaf area, and capitalize on early season moisture. In fact, one annual grass, medusahead, can reduce livestock carrying capacity by 50 to 80 percent. Invasive annual grasses typically have a shallow root system. Shallow root systems limit forage availability to early season use, particularly during drought years. Once these grasses gain a foothold, they can progressively dominate a system, as they germinate in the fall and generally “green up” earlier than our native grasses. Invasive annual grasses increase wildfire threat as they can provide an abundant source of dry “fine fuels” earlier in the season than native bunchgrasses.

The first step in managing these species is awareness of the annual grass and surrounding range conditions that are most at risk to invasion. Once an invasive annual grass has been identified in an area, strategies to limit their impact should be long-term and consistent to ensure the health of rangelands and pastures. The three major invasive annuals included in this publication are downy brome (cheatgrass), medusahead wildrye, and ventenata.

Fara Ann Brummer, Pete Schreder, Grace Haskins, and Jason Jaeger

E M 91 8 8February 2018

Map: Great Basin Landscape Conservation Cooperative

2

Nam

eTi

me

of G

erm

inat

ion/

Emer

genc

e/ S

eed

Dis

pers

alH

abit

at T

ypes

Gra

zing

Sui

tabi

lity

Non

chem

ical

Con

trol

Com

mon

ly U

sed

Her

bici

de C

ontr

olH

erbi

cide

Tim

e of

App

licat

ion

Dow

ny B

rom

e(C

heat

gras

s)(B

rom

us

tect

orum

)

Ger

min

atio

nFa

ll, fo

llow

ing

moi

stur

e ac

cum

ulat

ion

Emer

genc

e Ea

rly

fall

if m

oist

ure

is a

vaila

ble,

or i

n sp

ring

Esta

blis

hmen

t by

seed

, whi

ch is

pr

olifi

c. S

eed

can

be s

oil b

anke

d ov

er ti

me.

See

ds c

an p

ersi

st u

p to

5

year

s in

the

fiel

d.

Dis

turb

ed s

ites

ove

r a v

arie

ty

of s

oil t

ypes

Earl

y sp

ring

. (Pr

otei

n le

vels

ca

n be

20%

or m

ore)

. Se

edhe

ad a

wns

can

irri

tate

ey

es o

r cre

ate

abce

sses

in

late

sum

mer

. Can

be

graz

ed

in w

inte

r for

tar

gete

d co

ntro

l wit

h th

e us

e of

pr

otei

n su

pple

men

tati

on.

■

Pere

nnia

l gra

ss

esta

blis

hmen

t and

cov

er

■

Earl

y se

ason

gra

zing

wit

h ad

equa

te s

tock

ing

rate

■H

oein

g of

you

ng p

lant

s be

fore

see

dset

■

Mow

ing

can

redu

ce

seed

acc

umul

atio

n, b

ut

rem

aini

ng p

lant

s m

ay

regr

ow

■Se

ed b

uria

l by

tilli

ng

■

Bro

mac

il+

■

Gly

phos

ate+

■

Imaz

apic

+*

■

Tebu

thiu

ron+

Dep

endi

ng

on p

rodu

ct,

pre-

emer

gent

ap

plic

atio

ns

in fa

ll th

roug

h po

st-e

mer

gent

ap

plic

atio

ns in

sp

ring

are

mos

t eff

ecti

ve. C

heck

pr

oduc

t lab

el

and

cons

ult y

our

coun

ty o

r BLM

w

eed

spec

ialis

t.

Med

usah

ead

wild

rye

(Tae

niat

heru

m

capu

t-m

edus

ae)

Ger

min

atio

n M

ostl

y fa

ll, a

ltho

ugh

som

e ca

n ge

rmin

ate

in w

inte

r thr

ough

sp

ring

Em

erge

nce

Earl

y fa

ll th

roug

h sp

ring

, de

pend

ing

on m

oist

ure

cond

itio

ns

and

that

ch la

yer

Esta

blis

hmen

tB

y se

eds,

less

tha

n 6

feet

aw

ay

from

par

ent p

lant

. Mat

ure

seed

s ar

e di

sper

sed

from

July

–Oct

ober

. Se

eds

can

pers

ist 2

yea

rs in

the

fie

ld.

■

Soils

tha

t are

war

mer

, suc

h as

on

sout

h-fa

cing

slo

pes

and

burn

ed a

reas

■

Cla

y-do

min

ated

soi

ls

■

Mid

-spr

ing

■

Live

stoc

k w

ill g

raze

bef

ore

it fl

ower

s

■M

ay b

e gr

azed

in

win

ter w

ith

prot

ein

supp

lem

enta

tion

■

Hig

h si

lica

(6.4

% A

IA)*

may

lead

to lo

wer

inta

ke

rate

s.

■Se

edhe

ad a

wns

can

ir

rita

te e

yes

or c

reat

e ab

cess

es in

late

sum

mer

.

■

Pere

nnia

l gra

ss

esta

blis

hmen

t and

cov

er

■

Rem

ovin

g th

atch

laye

r by

raki

ng, p

resc

ribe

d bu

rnin

g,

or ti

llage

whe

re p

ossi

ble,

fo

llow

ed b

y re

seed

ing

■

Am

inop

yral

id+

■

Gly

phos

ate+

+

■Im

azap

ic+

■

Rim

sulfu

ron+

■

Sulfo

met

uron

*

Dep

endi

ng

on p

rodu

ct,

pre-

emer

gent

ap

plic

atio

ns

in fa

ll th

roug

h po

st-e

mer

gent

ap

plic

atio

ns in

sp

ring

are

mos

t eff

ecti

ve. C

heck

pr

oduc

t lab

el

and

cons

ult y

our

coun

ty o

r BLM

w

eed

spec

ialis

t.

Ven

tena

ta

(Ven

tena

ta

dubi

a)

Ger

min

atio

n: F

all (

soil

tem

pera

ture

bet

wee

n 48

o F –

84o F)

Emer

genc

e: F

all t

hrou

gh s

prin

g,

depe

ndin

g on

sit

e an

d ol

d ve

nten

ata

litte

r lev

el o

n si

teEs

tabl

ishm

ent:

See

d, w

hich

is

prod

uced

from

May

to A

ugus

t.

Seed

can

per

sist

up

to 2

yea

rs in

th

e fie

ld.

■

Are

as t

hat a

re w

et in

sp

ring

, and

dry

out

■

Cla

y-do

min

ated

soi

ls

■Sh

allo

w a

nd g

rave

lly s

oils

■

May

tak

e ov

er c

heat

gras

s an

d m

edus

haea

d si

tes

■

Mid

spr

ing,

app

roxi

mat

ely

2 w

eeks

to a

mon

th

late

r tha

n ch

eatg

rass

, an

d ty

pica

lly la

ter t

han

med

usah

ead

■

Silic

a (2

.7%

AIA

) may

co

ntri

bute

to c

oars

e na

ture

of p

lant

. Pla

nt

gene

rally

app

ears

un

pala

tabl

e to

live

stoc

k.

■

Imaz

apic

+

■

Rim

sulfu

ron+

■

Sulfo

met

uron

*

■

Sulfo

sulfu

ron

Late

fall.

Che

ck

prod

uct l

abel

an

d co

nsul

t you

r co

unty

or B

LM

wee

d sp

ecia

list.

+ H

erbi

cide

is a

ppro

ved

on B

LM-m

anag

ed g

roun

d on

wes

tern

U.S

. ran

gela

nds.

++

Her

bici

de is

app

rove

d on

BLM

-man

aged

gro

und

on w

este

rn U

.S. r

ange

land

s, b

ut m

ay N

OT

be a

eria

lly a

pplie

d.*

Cer

tain

form

ulat

ions

of t

his

chem

ical

may

not

be

aeri

ally

app

lied

on B

LM m

anag

ed g

roun

d on

wes

tern

U.S

. ran

gela

nds.

+* R

esis

tanc

e ha

s oc

curr

ed in

Gro

up 1

and

2 h

erbi

cide

s in

the

Pac

ific

Nor

thw

est.

Che

ck w

ith

your

loca

l BLM

offi

ce o

n sp

ecifi

c fo

rmul

atio

ns a

nd lo

cal r

estr

icti

ons.

For m

ore

deta

iled

info

rmat

ion,

con

tact

you

r loc

al E

xten

sion

age

nt, w

eed

man

agem

ent s

peci

alis

t, o

r cou

nty

wee

d m

aste

r.

3

Med

usah

ead

(Tae

niat

heru

m c

aput

-med

usae

)

Phot

o: F

ara

Bru

mm

er, ©

Ore

gon

Stat

e U

nive

rsit

yLe

aves

are

ver

y na

rrow

wit

h fin

e sh

ort

hair

s on

the

sur

face

and

leaf

mar

gins

. Ro

ots

are

very

sha

llow

. The

pla

nt c

an

ofte

n ha

ve a

cha

ract

eris

tic

yello

w-

gree

n co

lor.

Phot

o: G

race

Has

kins

, BLM

Med

usah

ead

wit

h de

velo

ping

see

dhea

ds. N

ote

the

coar

se, p

rom

inen

t aw

ns.

Phot

o: G

race

Has

kins

, BLM

An

inva

ded

site

on

the

sage

brus

h st

eppe

. Dry

med

usah

ead

plan

ts h

ave

a du

ll bu

ff c

olor

. Lit

ter a

ccum

ulat

ion

from

pre

viou

s ye

ars’

gro

wth

is

com

mon

and

bre

aks

dow

n sl

owly

.

Phot

o: M

att L

avin

, © M

onta

na S

tate

Uni

vers

ity

Foxt

ail (

Hor

deum

juba

tum

) may

als

o ap

pear

sim

ilar,

but t

he le

aves

are

qui

te

larg

e co

mpa

red

wit

h m

edus

ahea

d. It

al

so m

atur

es m

uch

earl

ier i

n sp

ring

, an

d it

inha

bits

diff

eren

t sit

es s

uch

as

was

te p

lace

s, o

ld c

orra

ls, a

nd h

oldi

ng

area

s.

Phot

o: M

att L

avin

, © M

onta

na S

tate

Uni

vers

ity

Squi

rrel

tail

(Ely

mus

elo

moi

des)

, at fi

rst g

lanc

e,

may

look

like

med

usah

ead

whe

n it

s se

eds

are

deve

lope

d, b

ut t

he a

wns

are

not

as

shar

p, a

nd t

he

head

s m

ay d

roop

. Als

o, s

quir

relt

ail i

s a

pere

nnia

l bu

nchg

rass

, not

an

annu

al. L

eave

s ar

e m

uch

wid

er

than

med

usah

ead

.

Dow

ny B

rom

e (C

heat

gras

s) (B

rom

us te

ctor

um)

Phot

o: F

ara

Bru

mm

er, ©

Ore

gon

Stat

e U

nive

rsit

yLe

aves

are

wid

e an

d so

ft to

th

e to

uch,

wit

h sm

all h

airs

on

bot

h si

des. Ph

oto:

Mat

t Lav

in, ©

Mon

tana

Sta

te U

nive

rsit

yFl

ower

ing

head

s dr

oop

dow

n as

the

y m

atur

e w

ith

seed

s.

Phot

o: M

att L

avin

, © M

onta

na S

tate

Uni

vers

ity

The

shar

p aw

n on

the

mat

ure

seed

head

is s

trai

ght a

nd lo

ng.

Phot

o: M

att L

avin

, © M

onta

na S

tate

Uni

vers

ity

A c

heat

gras

s-in

fest

ed lo

wer

ele

vati

on

sage

brus

h st

eppe

sit

e.

Phot

o: M

att L

avin

, © M

onta

na S

tate

Uni

vers

ity

Japa

nese

bro

me

(Bro

mus

japo

nicu

s) is

a lo

ok-a

like

to c

heat

gras

s. H

owev

er,

once

see

dhea

ds d

evel

op, t

he a

wns

are

sho

rter

and

can

hav

e a

bend

in

them

. Onc

e th

ey d

ry, t

hey

ofte

n be

nd o

ut a

t rig

ht a

ngle

s. Ja

pane

se b

rom

e ca

n al

so b

ecom

e w

eedy

, lik

e ch

eatg

rass

.

4

Ven

tena

ta (N

orth

Afr

ica

Wir

e G

rass

) (Ve

nten

ata

dubi

a)

Phot

o: F

ara

Bru

mm

er, ©

Ore

gon

Stat

e U

nive

rsit

yD

urin

g it

’s v

eget

ativ

e st

age,

ven

tena

ta h

as a

lo

ng li

gule

and

dar

k no

de.

Phot

o: F

ara

Bru

mm

er, ©

Ore

gon

Stat

e U

nive

rsit

yV

ente

nata

has

an

open

pan

icle

an

d ap

pear

s ve

ry ri

gid

whe

n dr

ied.

The

hea

ds d

o no

t nod

lik

e ch

eatg

rass

.

Phot

o: T

im P

rath

er, ©

Uni

vers

ity

of Id

aho

The

seed

head

on

vent

enat

a ha

s a

dist

inct

ivel

y be

nt a

wn.

Phot

o: F

ara

Bru

mm

er, ©

Ore

gon

Stat

e U

nive

rsit

yA

ven

tena

ta in

vade

d m

eado

w. V

ente

nata

freq

uent

ly h

as a

lim

e gr

een

colo

r dur

ing

it’s

ear

ly g

row

th.

Phot

o: F

ara

Bru

mm

er, ©

Ore

gon

Stat

e U

nive

rsit

yA

dom

inat

ed s

ite

can

accu

mul

ate

litte

r, w

hich

has

bee

n fo

und

to s

elf-

perp

etua

te V

ente

nata

.

Phot

o: C

arol

W. W

itha

m

Ven

tena

ta c

an

be c

onfu

sed

wit

h an

nual

hai

rgra

ss

(Des

cham

psia

da

ntho

nioi

des)

th

at h

as a

sim

ilar

appe

aran

ce w

hen

it

deve

lops

see

dhea

ds.

How

ever

, ann

ual

hair

gras

s is

a n

ativ

e,

and

nonc

ompe

titi

ve

wit

h ot

her g

rass

es.

It h

as t

wo

flore

ts p

er

spik

elet

, com

pare

d w

ith

vent

enat

a th

at

can

have

thr

ee. A

lso,

it

lack

s th

e da

rk re

d to

bla

ck n

odes

foun

d on

ven

tena

ta s

tem

s.

5

© 2018, Oregon State University. Extension work is a cooperative program of Oregon State University, the U.S. Department of Agriculture, and Oregon counties. Oregon State University Extension Service offers educational programs, activities, and materials without discrimination on the basis of race, color, national origin, religion, sex, gender identity (including gender expression), sexual orientation, disability, age, marital status, familial/parental status, income derived from a public assistance program, political beliefs, genetic information, veteran’s status, reprisal or retaliation for prior civil rights activity. (Not all prohibited bases apply to all programs.) Oregon State University Extension Service is an AA/EOE/Veterans/Disabled.

Published February 2018

Additional Resources:

Oregon State University Extension, Pacific Northwest’s Least Wanted List: Invasive Weed Identification and Management (EC 1563)

USDA NRCS Plant Materials website: https://plants.usda.gov

Ecologically Based Invasive Plant Management: website, manuals, and information at http://www.ebipm.org/

Medusahead Management Guide for the Western States. University of California, Weed Research and Information Center, Davis. www.wric.ucdavis.edu

References:

1. Bansal, S., R. Sheley. 2016. Annual Grass Invasion in Sagebrush Steppe: The Relative Importance of Climate, Soil Properties and Biotic Interactions. Oecologia. 181: 543–557

2. Cook, W., L. Harris. 1952. Nutritive Value of Cheatgrass and Crested Wheatgrass on Spring Ranges of Utah.

3. Davies, K.W. 2008. Medusahead Dispersal and Establishment in Sagebrush Steppe Plant Communities. Journal of Rangeland Management and Ecology. 61: 110–115

4. DiTomaso, J.M., G.B. Kyser et al. 2013. Weed Control in Natural Areas in the Western United States. Weed Research and Information Center, University of California. 544 pp

5. Hironka, M. 1961. The relative rate of root development of cheatgrass and medusahead. Journal of Range Management. 14, 263–267.

6. Kyser G.B., J.M. DiTomaso, K.W. Davies, J.S. Davy, B.S. Smith. 2014. Medusahead Management Guide for the Western States. University of California, Weed Research and Information Center, Davis. 68 p. www.wric.ucdavis.edu.

7. Miller, H.C., D. Clausnitzer, M.M. Borman. 1999. Medusahead. In Sheley, R. L. and J.K. Petroff (eds.). Biology and management of Noxious Rangeland Weeds. Oregon State University Press, Corvallis, OR.

8. Peachey, E., editor. 2017. Pacific Northwest Weed Management Handbook. Corvallis, OR. Oregon State University. http:pnwhandbooks.org/weed.

9. Wallace, J., T. Prather. 2016. Herbicide Control Strategies for Ventenata dubia in the Intermountain Pacific Northwest. Invasive Plant Science and Management, 9(2):128–137

10. Wallace, J., P. Pavek, T. Prather. 2015. Ecological Characteristics of Ventenata dubia in the Intermountain Pacific Northwest. Invasive Plant Science and Management. 8: 57–71