Download Noxious Weed Management and Native Plant Ecology

Noxious Weed
Ecology
© J. Mohler
Why should I care about weeds?
1 spotted knapweed plant = 300 flower heads =
140,000 seeds = densities of up to 2 million plants
per acres
Spotted knapweed roots are involved in chemical
warfare. The roots exude a substance called
catechin, which acts as an herbicide to inhibit
competition from other plant species.
Invasive Weed Spread
Weed
Annual Spread
Reduced Grazing
Canada Thistle
10%
42%
Leafy Spurge
12%
59%
Spotted
Knapweed
24%
80%
Source: Living on the Land v. 1, UNCE/WSARE
Weeds Impact Wildlife
• Reduce wildlife forage
• Alter thermal and escape cover
• Change water flow and availability to
wildlife
• Elk lose productive winter & spring
ranges, resulting in a decline in
numbers and a marked change in
distribution patterns
• In some cases, noxious weeds increase
soil surface runoff and sedimentation
into streams, a process many scientists
believe is the beginning of
desertification.
source: www.weedawareness.org
What are noxious weeds?
Plants species that are deemed to be invasive
and possess the capacity to negatively impact
the state's natural vegetation communities
and agricultural lands.
Noxious Weeds are defined in state law as exotic species which may
render land unfit for agriculture, forestry, livestock, wildlife, or other
beneficial uses or that may harm native plant communities and are
determined by Rule of the Montana Department of Agriculture (MDA)
under the provisions of the Montana County Weed Control Act.
Individual counties may further designate species as Noxious Weeds in
their respective jurisdictions.
Noxious vs Nuisance Weed
Oxeye Daisy
Dandelion
The three D’s of noxious weeds
• Damaging to the
economy or
environment
• Difficult to
control
• Tend to Dominate
a site
Image: MSU Extension Bulletin 134
How do weeds ensure their success?
• Competitive - grow well in spite of interference from other
plants
• Adaptable - to changing conditions
• Persistent
-will return year after year
-reproduce vigorously
-spread seeds effectively
© J. Mohler
Phases of Invasion:
Introduction, Colonization, Naturalization
•
•
•
•
Prevention
Eradication
Containment
Restoration
Step 1 - Identification
Montana Weed Control Association
www.mtweed.org
Gallatin-Big Sky Weed Committee
www.bigskyweeds.org
Houndstounge
Step 2 - Understand Weed Biology
Annual
– One season for all stages of development
– Produce foliage, flower seeds, then die
Musk Thistle
Biennials
–
–
–
–
Require two seasons for completion of life cycle
First year: develop roots and low-growing leaves
Second year: flowers, sets seed and matures
Examples are houndstounge & musk thistle
Perennials
Canada Thistle
– Live more than two years
– Will produce foliage, seed, and reach maturity year
after year
– Examples are leafy spurge and Canada thistle
Reproduction
Annuals & biennials
• Seed
• Seed Bank
Creeping roots of Canada Thistle
Perennials
• Reproduce by seed and roots
• Canada thistle - Creeping horizontal roots
sprout new plants and can reach more than
nineteen feet in one season. These roots can
also go as deep as twenty two feet.
Seed Production & Seed Bank
Seed Production
• One spotted knapweed plant can produce up to 140,000 seeds, and seeds
have been shown to remain viable in the soil for up to 8 years
Seed Bank = the store of seeds in the soil
• Proportion of viable seed in seed bank decreases with decreased disturbance
frequency
• Seed predation: by birds, rodents, insects, worms, microbes
Denmark: 600 year old seeds
were found in a monastery.
11 seeds germinated!
How do weeds spread?
© J. Mohler
Dalmation toadflax was
planted in the gardens
around Mammoth in
YNP for table flower
arrangements. It quickly
escaped cultivation and
aggressively reproduced
in the surrounding area.
• Natural means
– wind
– water
– animals
• Mechanical means
– irrigation
– harrowing & spreading
manure
– construction/fill dirt
– vehicles
– tillage
– contaminated seed or feed
– ornamental plants
Disturbance
Disturbances open up habitat that is suitable for
pioneer species by making available light, water,
nutrients or bare soil that theses species require.
Natural = hurricanes, fires,
floods, pests, & diseases
Man made = building
roads, construction,
grazing, etc.
Step 3: Understand
Weed Management
Prevention is the first line of
defense to keep weeds from
occurring or increasing.
Eradication is the removal of
weeds from an area so they will
not recur unless reintroduced.
Control reduces a weed population
to a manageable level
Noxious weed reality check
– in general, it takes
several years of repeated
management to reduce or
eliminate the population.
Preventing Invasion & Spread of Weeds
•
•
•
•
Minimize soil disturbance and bare ground
Don’t overgraze pastures
Avoid driving in weed infested areas
Don’t transport flowering plants that you cannot
identify
• Pull small patches before seed is formed
• Collect burs / seeds that stick you to & your dog and
throw away!
• Carefully remove weeds that have flowered – cut and
bag flowers & seeds!
Eradication
• Removal of all weeds of a given species from an area so
they will not recur unless reintroduced
• Must deplete seed bank of viable weed seeds by
controlling all seedlings
• Requires yearly management for multiple years
• Must revegetate the area with competitive vegetation
The best time to control weeds is in the first
growing season, when they are all “annuals”.
Control
• Mechanical controls
• Biological controls
• Chemical controls
Mechanical Treatments
•
•
•
•
Cultivation/tillage
Hoeing
Burning
Hand-pulling – always
wear gloves & bag
those weeds!! Best for
tap rooted plants.
• Mowing
Mowing weeds
• Weeds can adapt to mowing…and even be encouraged to
spread!!! Canada thistle & leafy spurge send up more tillers,
spotted knapweed adapts by spreading low to the ground.
• The best time to mow is just before the target weed reaches
the flowering stage (reduces seed production & seed bank)
• If already gone to seed, you may be spreading the weed seeds
around!
• A combination of mowing and spraying can be a good 1-2
punch!
• Don’t mow lower than 3-4 inches, as you’ll set your grasses
back
Biological Treatments
Biological control is the use of one
organism to suppress another
• More effective in combination with other treatment
• Can reduce herbicide use
• Goal is not total elimination, just to lower general
equilibrium
• Remember: the weed is their food, so bio controls
goal is not to eliminate the weed!
• Slower acting control
• Great for areas where spraying is not an option:
wetlands, riparian areas, steep slopes
Photos: Living on the Land v.1,
UNCE/WSARE
Chemical Treatments
Wear protective clothing:
Eye protection
Long sleeve shirt
Chemical resistant gloves
Long pants
Rubber boots
Always read & follow the label
• Select the correct herbicide for the weed species you
have!!
• Understand when& where to apply herbicides
• Correctly apply herbicide through calibration
• Mix & handle herbicides property
• Safely store & dispose of herbicides
To be effective, a herbicide application must have:
• Proper placement – appropriate dose, proper calibration
• Even distribution – depends on nozzle shape & size,
nozzle position, pressure
• Proper timing – apply when weeds are most susceptible
(bolting stage or time of active growth)
Caution!! Herbicide Carryover
Herbicides can persist in
hay, manure, compost, &
grass clippings.
These herbicides eventually break down
through exposure to sunlight, soil
microbes, heat, and moisture.
Depending on the situation, the herbicides
can be deactivated in as few as 30 days,
but some field reports indicate that
breakdown can take as long as three to
five years.
Herbicide carryover
can kill your garden!
© J. Mohler
A healthy stand of desirable / native vegetation is your best
defense against weeds!!
The mark of a healthy landscape is species diversity grasses, forbs, shrubs, trees
Native Plants
Once established, native plants are
easy to maintain because they are
adapted to Montana temperatures,
rainfall patterns, and soil conditions.
They resist local pests and disease.
Native plants reduce soil erosion,
build soil structure, and absorb
rainfall.
Native plants are preferred by native
birds and wildlife for food &
shelter.
© J. Mohler
Xeriscape
• It integrates the principals of several conservation initiatives
such as:
– Reduces water, energy, and chemical usage
– Reduces maintenance (cost & time)
– Wildlife habitat enhancement
– Invasive weed management
– Promoting native plants
Landscaping with native plants
• Many resources available online
– Montana Native Plant Society
– www.bigskyweeds.org – on “Weed ID & Control” page
Canada thistle (Cirsium arvense)
• Asteraceae (Sunflower family)
• Colony-forming perennial
• Reproduces vegetatively by rhizomatous roots or by
seeds
• Leaves are spine-tipped and wavy
• Flowers are both male and female on separate plants
Hoary alyssum (Berteroa incana)
• Brassicaceae (Mustard family)
• Annual, biennial, or short-lived perennial
forb
• Tap root
• Reproduces from seeds
• Plants first form a basal rosette or leaves,
followed by an upright, central stem 1-3
feet tall
• “Hoary” comes from rough hairs on
stems, leaves, & fruit
• Numerous white flowers with four
deeply divided or notched petals
• Toxic to horses
Houndstongue (Cynoglossum officinale)
• Boraginaceae (Borage family)
• Biennial forb with a tap root
• Reproduces by seeds/burr-like nutlets
• Velvety leaves lack teeth or lobes – rough to the
touch
• Flowers have five reddish-purple petals
• Toxic to horses
Musk thistle (Carduus nutans)
• Asteraceae (Sunflower
family)
• Biennial, perennial forb
• Flower heads droop on the
stem when fully developed,
giving musk thistle its other
common name, “nodding
thistle.”
• Seeds are carried on the wind
with the aid of a pappus of fine
bristles. The seeds may remain
viable in the soil for as long as
a decade.
Spotted knapweed (Centaurea maculosa)
• Asteraceae (Sunflower family)
• Short lived perennial,
sometimes biennial
• Flowers are pinkish-purple, one
per stemmed branch, ~300 per
plant
• Floral bracts are tipped with
dark comb-like fringe
• Deep taproots help this plant
compete for water and other
essential nutrients
• Secondary compounds may
cause allergic reactions in some
people
Oxeye daisy (Chrysanthemum leucanthemum)
• Asteraceae (Sunflower
family)
• Showy perennial herb
• Reproduces by seed or
vegetatively by rhizomes
• Leaves have rounded
teeth, widest at the tip
• Flowers consist of white
ray flowers (long petals)
and yellow disk flowers
(center of the flower
head).
Shasta Daisey on left, Oxeye daisy on right
Yellow toadflax (Linaria vulgaria)
• Scrophulariaceae (Figwort
family)
• Perennial
• Reproduces by seeds and
underground rootstalks
• Leaves are pale green, numerous,
narrow, pointed at both ends
• Flowers are 1” long with bearded
orange throat
Review
• Identify weeds correctly
• Create a management plan that
takes into account the biology
and ecology of the property
• Promoting healthy/competitive
vegetation
• Use all the tools in the weed
management tool box!
© J. Mohler
Review
Properly use herbicides
• Select based on the noxious weeds present
• Calibration – a must for proper application
• Apply at the right time
• Follow the label – it’s the law
If you don’t know – get help!!!
Adaptive Management
Successful weed management requires constant vigilance!
Successful weed eradication requires yearly
treatment for many years.
Help Available
Gallatin-Big Sky Weed Committee
www.bigskyweeds.org
[email protected], 406-209-0905
Click on “Weed ID & Control” page for info on pet safety, how to calibrate a sprayer,
herbicide carryover, “cheat” sheets for each noxious weed species, etc.
Gallatin County Weed District 582-3265
- Cost share
- Sprayer rental
- Property inspections
- Enforcement & compliance
Montana Weed Control Association www.mtweed.org
Acknowledgements
Adapted with permission from Living on the Land: Stewardship for Small Acreages, copyright
2001 University of Nevada Cooperative Extension/WSARE, UNCE CM-03-07
Additional sources:
Montana Weed Control Association
http://www.mtweed.org/
Montana's Statewide Noxious Weed Awareness and Education Campaign
http://www.weedawareness.org/
Center for Invasive Plant Management
http://www.weedcenter.org/
Montana State University Department of Animal & Range Sciences
http://animalrange.montana.edu/
Colorado State University’s Guide to Poisonous Plants
http://www.vth.colostate.edu/poisonous_plants/