Noxious Weed Ecology J Mohler Why should I

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 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

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 info@bigskyweeds. org, 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/