WEED NEWS & INFORMATION BULLETIN FLATHEAD COUNTY WEED DEPARTMENT patches) SPOTTED KNAPWEED Montana Priority 28 WWW.FLATHEAD.MT.GOV/WEEDS WEEDSCOMPLIANCE@FLATHEAD.MT.GOV 406.758.5798 Noelings, Rathead County Flowers are pink or purple and fan-like with many thin petals protruding from a spotted bud that is reminiscent of decorative artichoke. Leaves are deeply and sometimes irregularly lobed and the many stems of the plant originate from the rosette - the base of the plant. These weeds can get larger but generally reach 2-3 feet tall and have a large taproot. In some studies this plant has shown to be allelopathic, meaning it leaches chemicals into the soil around it to prevent other plants from geminating, thus eliminating any competition for soil resources and light. A single knapweed plant can produce up to 140,000 seeds in I growing season. How to Treat Prevention Pre-Bloom/Regrowth Herbicide (repeat applications) Hand-pulling (only acceptable in small Grazing (sheep/goats) Mowing REMEMBER: If using herbicide, read the label. THE LABEL IS THE LAW. NOBLE YARROW Flathead County Priority 3 Noel Jinings, Flathead Courty Noble yarrow is an escaped ornamental perennial flower that can be extremely aggressive, taking over whole pastures. There is a native yarrow, but it is generally found in forested settings. The flowers of a yarrow plant are made up of flat topped clusters of small white flowers. Yarrow leaves are feathery and almost fer-like. The leaves are found in a clump at the base of the plant and sparsely up the stem. This plant tolerates all soil types and environmental conditions. Because yarrow is a thizomatous plant, it can be very difficult to control with mechanical methods. Yarrow is frequently found in store bought wildflower mixes. Use caution when purchasing and planting "wildflowers" from a seed packet. How to Treat Pre-Bloom Herbicide Tilling (has to occur repeatedly) Provide Competitive Forbs Hand-pulling >Burning Mowing ST. JOHNSWORT Montana Priority 28 1552178 Ohio State Weed Lab, The Ohio State University, Bugwood.org St. Johnswort, also known as goatweed, is an erect, multi-stemmed perennial that generally grows between 1-3 feet tall. The flowers are bright yellow-orange, bordered by black speckles, and are complimented by very recognizable rounded leaves than when held up to the sun, have distinct pin-hole markings. The stems are woody and tend to be reddish in color. Each plant can product between 15,000-30,000 seeds that can remain viable for 50+ years according to some records. Since these plants contain hypericin, ingestion by livestock, especially light skinned animals, can lead to the development of lesions and blisters, and delayed symptoms such as coma, convulsions and death after consuming this plant. How to Treat Pre-Bloom Herbicide (will need repeated) Tilling (regrowth can occur, must be repeated) Mowing (only if paired with herbicide app) Hand-pulling (only on small or new sites) Grazing (MUST be carefully managed) Burning COMMON TANSY Montana Priority 28 5474273 Rob Routledge, Saul College, Bugwood.org Common tansy plants are sturdy, aromatic perennials with large fern-like foliage and attractive yellow button flowers. Each plant can reach up to 5 feet tall and produces many flowering heads made up of dense clusters of %½ inch disk shaped flowers that bloom from July to September. The stems tend to be purplish-red, especially close to the ground, and are sometimes hairy. Each plant can produce around 50,000 seeds per season. Although generally found in moist areas, common tansy can grow along roadsides, trails, natural areas, pastures, forest areas, field margins, mining areas, and unmaintained gravel pits. How to Treat Prevention Pre-Bloom Herbicide Manual Removal(of small or new infestations) Mowing Grazing (ONLY goats/sheep-toxic to other animals) Tilling Baming (unless used prior to herbicide app) WEED NEWS & INFORMATION BULLETIN FLATHEAD COUNTY WEED DEPARTMENT patches ) SPOTTED KNAPWEED Montana Priority 28 WWW.FLATHEAD.MT.GOV/WEEDS WEEDSCOMPLIANCE@FLATHEAD.MT.GOV 406.758.5798 Noelings , Rathead County Flowers are pink or purple and fan - like with many thin petals protruding from a spotted bud that is reminiscent of decorative artichoke . Leaves are deeply and sometimes irregularly lobed and the many stems of the plant originate from the rosette - the base of the plant . These weeds can get larger but generally reach 2-3 feet tall and have a large taproot . In some studies this plant has shown to be allelopathic , meaning it leaches chemicals into the soil around it to prevent other plants from geminating , thus eliminating any competition for soil resources and light . A single knapweed plant can produce up to 140,000 seeds in I growing season . How to Treat Prevention Pre - Bloom / Regrowth Herbicide ( repeat applications ) Hand - pulling ( only acceptable in small Grazing ( sheep / goats ) Mowing REMEMBER : If using herbicide , read the label . THE LABEL IS THE LAW . NOBLE YARROW Flathead County Priority 3 Noel Jinings , Flathead Courty Noble yarrow is an escaped ornamental perennial flower that can be extremely aggressive , taking over whole pastures . There is a native yarrow , but it is generally found in forested settings . The flowers of a yarrow plant are made up of flat topped clusters of small white flowers . Yarrow leaves are feathery and almost fer - like . The leaves are found in a clump at the base of the plant and sparsely up the stem . This plant tolerates all soil types and environmental conditions . Because yarrow is a thizomatous plant , it can be very difficult to control with mechanical methods . Yarrow is frequently found in store bought wildflower mixes . Use caution when purchasing and planting " wildflowers " from a seed packet . How to Treat Pre - Bloom Herbicide Tilling ( has to occur repeatedly ) Provide Competitive Forbs Hand - pulling > Burning Mowing ST . JOHNSWORT Montana Priority 28 1552178 Ohio State Weed Lab , The Ohio State University , Bugwood.org St. Johnswort , also known as goatweed , is an erect , multi - stemmed perennial that generally grows between 1-3 feet tall . The flowers are bright yellow - orange , bordered by black speckles , and are complimented by very recognizable rounded leaves than when held up to the sun , have distinct pin - hole markings . The stems are woody and tend to be reddish in color . Each plant can product between 15,000-30,000 seeds that can remain viable for 50+ years according to some records . Since these plants contain hypericin , ingestion by livestock , especially light skinned animals , can lead to the development of lesions and blisters , and delayed symptoms such as coma , convulsions and death after consuming this plant . How to Treat Pre - Bloom Herbicide ( will need repeated ) Tilling ( regrowth can occur , must be repeated ) Mowing ( only if paired with herbicide app ) Hand - pulling ( only on small or new sites ) Grazing ( MUST be carefully managed ) Burning COMMON TANSY Montana Priority 28 5474273 Rob Routledge , Saul College , Bugwood.org Common tansy plants are sturdy , aromatic perennials with large fern - like foliage and attractive yellow button flowers . Each plant can reach up to 5 feet tall and produces many flowering heads made up of dense clusters of % ½ inch disk shaped flowers that bloom from July to September . The stems tend to be purplish - red , especially close to the ground , and are sometimes hairy . Each plant can produce around 50,000 seeds per season . Although generally found in moist areas , common tansy can grow along roadsides , trails , natural areas , pastures , forest areas , field margins , mining areas , and unmaintained gravel pits . How to Treat Prevention Pre - Bloom Herbicide Manual Removal ( of small or new infestations ) Mowing Grazing ( ONLY goats / sheep - toxic to other animals ) Tilling Baming ( unless used prior to herbicide app )