GBNPSI Pest Management Update
Grass pests (mostly)
Bob Hammon
Colorado State University
Tri River Area Extension
Grand Junction CO
Aphids in Native Grasses
Gary Puterka
USDA/ARS
Stillwater OK
Russian Wheat Aphid
Diuraphis noxia
• RWA has caused $250,000,000+
in damage to western US wheat
since it arrived in 1986
• Occasional problem in new
seedings of wheatgrass/wild rye
• Some wheatgrasses ,wild ryes
and bromes are oversummering
hosts
• They provide habitat for
holocyclic reproduction
– important in biotype
development
1.5 mm
Dtrit 4x
D. frequens
on Blue Wild Rye
D. tritici
on wheat
D. mexicana
on Mountain Brome
D. noxia
on wheat
Diuraphis Damage
Symptoms
• Linear streaking on leaves
• Red, white, yellow
• Leaf rolling
• Feeding on newest leaf
• Symptoms from a single aphid
• Wheatgrasses, wildryes, mt brome, winter
annual grasses
• New seedings most vulnerable
• prior to 1st seed crop
• RWA populations will vary wildly
• Other species show population stability
Severe RWA damage to ‘Luna’ Pubescent WG
Holocyclic Reproduction in RWA
1st eggs found in April 2007
wheat, intermediate WG, Elymus
Holocyclic population in spring 2009
Mt brome seed field
Why is sexual reproduction in RWA important?
• More than 40 biotypes were found after holocyclic reproduction in 2007
• Source of genetic diversity responsible for overcoming wheat resistance
Diuraphis mexicana aka D. nodulus
• Present distribution: UCEPC
• Perennial pest of some
B. marginata accessions
• ‘Garnet’ is infested
• ‘Teton’ is not
• Sprays are applied annually
at UCEPC
• pre heading
• Ass’n w/powdery mildew?
D. mexicana damage to Mt Brome, UCEPC
Western Wheat Aphid
Diuraphis tritici
• A significant wheat pest in CO &
MT in 1910’s
• Disappeared until 1990’s
• RWA triggered search
• Found in mt brome seed fields
• Present in some accessions
• ‘Teton’, not ‘Garnet’ at UCEPC
• UP & Routt/MB at WCRC@RM
• Occasionally found in wheat
Head Smut Research
Manuel Rosales
Upper Colorado Environmental Plant Center, Meeker CO
Presently Manager, Tucson Plant Materials Center
Head Smut
Ustilago bullata
• Present in several Bromus spp
• ‘Bromar’ susceptible to smut
– Infection rate near 100%
– Severely limited seed production
• ‘Garnet’ selected for resistance
– resistance quickly broke down
• Production limiting pathogen!
Head Smut Control Study
Upper Colorado Environmental Plant Center, Meeker CO
Manuel Rosales
2007
Clean
Seed
2008
Infected
Seed
Clean
Seed
Infected
Seed
% Infected seed at harvest
Untreated
0.0
64.7**
0.0
34.3
Dividend
2.1
11.7
0.0
0.77
Vitavax
1.1
1.1
0.0
0.27
Flea Beetles in Elymus glaucus
Chaetocnema subconvexa
Chaetocnema subconvexa
• Recently described species (1996)
– Dr Shawn Clark, BYU
• Widespread in NW CO wheat
• Caused enough damage in Elymus glaucus
at UCEPC to justify plow-out
• Larvae cause damage, not adults
– They are unknown!!!
• Weak growth, no seed heads
– monitor for adults in June/July
– sweep net or vacuum sampler
– adult control before egg laying
Checkered Melon
Leaf Beetle
Paranapiacaba tricincta
• Abundant in blue grama
& galleta
– 5 per sweep
• Adults known as forb
leaf feeders
• Pollen feeders in grass
seed fields
• Larvae are unknown
• Grass root feeders?
Pyemotes Itch Mites
• ‘Alma’ blue grama
– Not ‘Hachita’ or ‘Lovington’
•
•
•
•
Seed handlers with dermatitis
Only on stored seed
Mites found on seed bags
Predatory, move when food
supplies are exhausted
• Anyone else with similar
experience?
400X magnification
ID by Dr David Walter
Royal Alberta Museum
Edmonton AB
Other Insects to Watch For
Ebony bugs in Penstemon
• flower, bud & foliar
feeding
• overwintering in
seed pods
• other scrophs?
Scale & Mealybugs in Atriplex
The Irregular Wax Scale
Ceroplastes irregularis Cockerell
Chenopod Ensign Coccid
Orthezia annae Cockrell
Call for Bugs
If you see insect issues with any species of seed
production, let me know!
Collect specimens –
live if possible, with host plant
KEEP OUT OF SUN / keep dry
refrigerate short term storage
call to work out transportation
Photograph (site, damage, insect)
Document (date, location, host, damage)
Bob Hammon
Area Extension Agent (Entomology / Agronomy)
Colorado State University, Tri River Area Extension
Grand Junction CO
bob.hammon@mesacounty.us
Western Colorado Insects; http://wci.colostate.edu