Noxious

Definitions Weed – a plant in the wrong place Noxious Weed Invasive Non native Can be toxic Aggressive Hard to control

Review of Plant Life Cycles Annual Summer Winter Biennial Rosette Bolting

Perennial Rhizome Stolon Underground stems Simple Creeping

Control Methods Cultural Mechanical Chemical Biological Preventative IWM – no one method can stand alone

Noxious weeds Colorado Noxious Weed Law 35-5.5 A mandate for everyone to control weeds because they threaten the economic and environmental health of the state Definition by law Criteria for listing a noxious weed State Weed List

Delta County Noxious Weeds List Chart of life cycles Best management practices Obnoxious Weeds (Unlisted by undesirable)

Class I – Public and private lands Toadflax, yellow x Knapweed, diffuse x Scotch thistle x Houndstongue x Musk thistle x Hoary cress (Whitetop) x Leafy spurge x Common St. Johnswort x Knapweed, spotted x Common burdock x Knapweed, Russian x Canada thistle x

Class II – Public Lands Tamarisk (Saltcedar) x Poison hemlock x Sage, Mediterranean x Oxeye daisy x Russian olive x Jointed goatgrass x Purple loosestrife x Halogeton x Puncturevine x Field bindweed x

Additional Noxious Weeds X Dalmation Toadflax X Yellow Star Thistle x X X Plumeless Thistle x X Dyer’s Woad X X Bull Thistle x Mesa Montrose

Additional Common Weeds Common mallow Curly dock Prickly Lettuce Purslane Red Root Pigweed

Thistles with Spines Bull Thistle Musk Thistle Plumeless Thistle Scotch Thistle Yellow Starthistle Canada Thistle

Bull Thistle Biennial erect, many spreading branches Rosette first year, flowering stem second year Leaves: Green, sparsely hairy, with short prickles on the surface, cottony below Sharp spines on the margins Stems: Stout, 2 ft. to 5 ft. tall with spiny wings from leaves Flower: Terminal, more or less clustered, 1 1/2 to 2 inches wide, flowers dark purple, bracts spine tipped Roots: Short, fleshy taproot Seeds: Straw colored, striped lengthwise with brown or black, a protrusion at one end Reproduce by seed only .

Bull Thistle blooms June through the summer 2 nd year Greener than musk thistle Musk thistle flowers not vase shaped , but more open and less compact. Control plants before plants bolt Rosettes should be killed manually or with herbicides in the spring or fall Plants bolting removed manually or sprayed ASAP Flowering plants manually and mature flowerheads bagged to prevent seed spread. Control Methods: Severing the tap root at least 2" below the soil line before flowering is very effective Herbicides can be used in the rosette to early bolting stage Status in Mesa County: Scattered and occasional; in higher altitude pastures and disturbed sites.

Musk Thistle ( Carduus nutans )

Musk Thistle Carduus nutans Biennial 6 feet tall Leaves - dark green spined edges, lobed, wavy Rosette leaves spiny; white central vein very visible on the underside leaves clasp the stem;form "wings" along the stem below the leaf Flowers borne singly on long spineless stems flowers are deep pink to magenta and 1½ to 3 inches very broad green bracts below the petals When mature, the flowers "nod", hence the other common name, nodding thistle.

Musk Thistle Similar Species: Plumeless thistle, another noxious species, has spined wings along the stem under the flowerhead and the flowers may occur in clusters of 2-5 flowers Bull thistle, another noxious species, is shorter and the lobes of the leaves are pointed at right angles to the main vein None of our native thistles are similar to musk thistle.

Musk Thistle Control Timing: In the rosette and early bolting stage. Target: Prevent seed production. Methods: Severing the tap root at least 2" below the soil line before flowering is very effective Herbicides can be used in the rosette to early bolting stage Flowering plants should be chopped and bagged to prevent spread of seeds Several insects species are available for biological control. Status in Mesa County: Widespread in higher elevations of eastern Mesa County on roadsides and in pastures. Rarely found in lower elevations in Mesa County.

Plumeless Thistle Carduus acanthoides Annual highly branched tap rooted biennial thistle up to 4 feet tall Rosette leaves are 4 to 8 inches long, green, with spined lobes Stem leaves have "wings" that grow to the stems Flower stems also winged . The purple flowers are either solitary or in a cluster of 2-5 Flowers rarely white or yellowish Bracts under the petals are hairy and narrow .

Similar Species: Musk thistle has larger bracts and flowers, and the flower stems are not winged. Bull thistle is shorter and not as spiny with more compact flowers. Flowers of the rare native species, Cirsium perplexans , are borne singly rather than in clusters and the stems are not profusely winged. Cirsium traceyi (formerly C. undulatum and called wavy leaf thistle), another native thistle, is not profusely branched, has silver gray leaves and the stems are not winged.

Plumeless Thistle Control Timing: In the rosette and early bolting stages. Target: Prevent seed production. Methods: Severing the tap root at least 2" below the soil line before flowering is very effective Herbicides can be used in the rosette to early bolting stage Flowering plants should be chopped and bagged to prevent spread of seeds Several insects species are available for biological control. Status in Mesa County: Infestations have been found in Devil’s Canyon near Fruita and in Rifle (Garfield County). Otherwise it is not widespread in Mesa County

Scotch Thistle ( Onopordum acanthium )

Scotch Thistle Onopordum acanthium Biennial tap rooted To 12’ Rosette leaves very large (1 to 2 feet long and 6 to 12 inches wide) spined dense coating of white hairs Looks silvery green Flowers numerous magenta 2 “ or more Stems are winged, including those under the flowerheads Truly an enormous plant. Similar Species: No other thistles reach this size or have leaves or flowers this large.

Scotch Thistle Control Timing: In the rosette stage. Prevent seed production. Mechanical control very effective in the rosette stage root is severed at least 2 inches below the soil line Roots are very thick and may need to be chopped Herbicides must be applied to the rosette The older the plant gets, the more difficult it is to control with herbicides because the hairiness of the leaves prevents the herbicide from landing on the leaf surface The addition of a surfactant or adjuvant is recommended No biocontrol agents are available at this time. Status in Mesa County: A serious problem in the Collbran area. A small infestation was found on Glade Park. A few plants are found occasionally in lower elevations of Mesa County.

Yellow Starthistle Centaurea solstitialis

Yellow Starthistle Annual – long lived Winter Annual Tap root 2 feet tall rosettes 6 to 8 inches across like a dandelion distinct triangular tip Flowers Yellow; ½ wide; summer bloomer

Yellow Starthistle Seed production is very high Bracts at the base of the petals are armed with stout spines up to 1½ inch long No other part of the plant has spines Leaves are reduced and grayish green Plants are much branched and spindly looking.

Yellow Starthistle Similar Species: Curlycup gumweed is much greener, rosette leaves are less lobed, and the flower bracts are not armed with spines, but have curled bract tips Buffalo bur, a native weedy species, is often confused with starthistle. Buffalo bur has spines allover the leaf and stem surfaces, and has yellow bell shaped flowers. The leaves are broad and deeply lobed. Several other species in the aster family, such as wild lettuce, sowthistles, and dandelions, have yellow flowers but none are spined. Curlycup Gumweed Buffalo Bur

Yellow Starthistle Control Timing: rosette to early bolting stage. Prevent seed production. Mechanical control works well on small infestations but is labor intensive for large infestations Herbicides during the rosette to early bolting stage Repeat applications are necessary because the seeds germinate over the entire summer A seedhead fly, accidentally introduced to California, feeds on seeds but is currently not available Good pasture management is necessary to keep starthistle populations from exploding. Status in Mesa County: There is a large infestation south of the town of Mesa in the Coon Creek Estates area. A smaller infestation occurs on Glade Park on DS Road. Mesa County is actively involved in monitoring infestations and working with landowners on eradication of these patches.

Canada Thistle Cirsium arvense Top Underside

Canada Thistle Identification: deeply rooted Perennial spreads from rhizomatous roots also produces large numbers of seeds Leaves Alternate on the stem and are spined along the edges Flowers purple small, about ½" to 3/4" in diameter grow in a cluster at the branch tips may have a sweet smell;visited by bees and other pollinators 1-4 feet tall and are usually in large clumps Similar Species: Several species of native thistles are mistaken for Canada thistle

Canada Thistle Control Timing: Spring and Fall Prevent seed production and stress root system. Control difficult Herbicides most effective with mowing Mechanical ineffective and may cause the plant to spread or produce more stems Seeding with competitive desirable grasses highly recommended See CSU Extension Service Fact Sheet No. 3108 for more information on control methods Biocontrol agents are available. Status in Mesa County: Problem in higher elevation forest lands, high country meadows, and along drainages.

Knapweeds Russian Knapweed Spotted Knapweed Diffuse Knapweed

Russian Knapweed Acroptilon [ Centaurea ] repens

Russian Knapweed Acroptilon [ Centaurea ] repens rhizomatous perennial weed silvery green up to 3 feet tall Rosette leaves lobed ; 3-5 inches long Stem leaves linear, not toothed, 1 to 2 inches long Flowers May to June. occasionally late summer Purple, ½ inch bracts below the petals - soft and greenish tan Roots are black and scaly Leaves of Russian knapweed release an allelopathic chemical to the soil, which prevents any other species from germinating from seed.

Russian Knapweed Similar Species: Diffuse and spotted knapweed have similar flowers, but both have fern-like leaves throughout and the bracts under the flowers differ from Russian knapweed. Purple aster ( Aster macaeranthera ) has very green leaves and the flowers have a yellow center. This plant blooms in the late summer and early fall.

Russian Knapweed in a Craw Space

Comparison Purple Aster, Diffuse Knapweed, Spotted Knapweed, Russian Knapweed

Russian Knapweed Control Timing: bud to bloom stage and late summer and fall Prevent seed production,stress roots Herbicides are the only method known that provides good control results Repeated pulling or digging may work for very small or new infestations, but must be done over a long period of time Tillage spreads small root pieces can sprout into new plants Planting competitive plants is necessary following herbicide application The soil must be tilled and left for a week or two before planting to allow the knapweed’s allelopathic chemical to dissipate CSU Extension Service Fact Sheet No. 3.111 details control methods and seeding recommendations.

Russian Knapweed Status in Mesa County: Widespread in lower elevations of Mesa County. Some patches are beginning to show up in higher elevations. Very abundant on the Dolores, Gunnison and Colorado Rivers. Occurs on roadsides, in degraded pastures and range, on neglected farmland, and in disturbed sites. Hoary cress and Russian knapweed are the County’s two most abundant noxious weeds. Toxicity : Russian knapweed is toxic to horses, causing nigropallidial encephalomalacia, a Parkinson’s-like neurological disease, that results in the inability to chew followed by starvation. Although toxicity to humans is undocumented, cases of tumors, illness from burning plants, and a garlic-like taste in the mouth have been reported. It is essential to wear gloves when working with this plant.

Spotted Knapweed Comparison: spotted knapweed (above) diffuse knapweed (below- white). Note the dark bracts sticking out from the flower bud on spotted knapweed (giving it its name: spotted), and the smaller more green bracts on the diffuse knapweed.

Spotted Knapweed Centaurea maculosa

Spotted Knapweed A biennial or short lived perennial profusely branched to 3 feet tall Plants have a stout tap root Rosette leaves strongly lobed or not and 3 to 6 inches long Flowers are pink to magenta, rarely white solitary on the tips of branches Bracts below the flower petals have dark, toothed margins that look like spots . Similar Species: Diffuse knapweed has a comb-like fringe on the bracts and no spots. Russian knapweed has soft, greenish-tan bracts without a fringe or spots.

Spotted Knapweed Control In the rosette or early bolting stage. Control target: Prevent seed production. Mechanical control may work for small infestations, but must be repeated because shoots can arise from the tap root Digging up the entire root is preferable but labor intensive Tillage at the rosette stage can be effective Herbicides are effective is applied to the rosette stage Mature flowers should be removed and bagged to prevent seed spread. Some biocontrol agents are available, including seed and stem feeders. Status in Mesa County: Very small infestations exist in Mesa County on Glade Park, on Silt Divide Road, on Lands End Road, and Highway 65 north of Powderhorn. Plants are found occasionally in lower elevations of Mesa County.

Diffuse Knapweed Comparison: spotted knapweed (above) diffuse knapweed (below- white). Note the dark bracts sticking out from the flower bud on spotted knapweed (giving it its name: spotted), and the smaller more green bracts on the diffuse knapweed.

Diffuse Knapweed Centaurea diffusa

Diffuse Knapweed annual or short lived perennial profusely branched grows to 2 feet tall Rosette and stem leaves are deeply lobed. Produces numerous white to pale lavender flowers bloom in early to mid summer Bracts below the petals are spine tipped, with comb-like spines, fringed appearance Plants break off at the base and become tumbleweeds, facilitating seed spread Similar Species Russian knapweed leaves are not lobed and its flowers are darker purple Spotted knapweed has spots on the bracts below the flowers

Diffuse Knapweed Control In the rosette or early bolting stages Prevent seed production Mechanical removal is effective on rosettes and plants in the early bolting stage Herbicides are effective tools if applied before flowering Once the plants have flowered, they should be removed manually and bagged to prevent seed spread. Status in Mesa County: A large infestation exists at the Garfield/Mesa County line on I-70. Scattered plants may exist along I-70 throughout Mesa County. A large infestation exists in the Bookcliffs on Bureau of Land Management land; it is being treated. A large infestation was found in 1998 on property owned by Public Service Company located east of 34 Road on C Road. This patch is being controlled with herbicides and is being monitored by the Mesa County Pest and Weed Inspector. A few dozen plants were found and removed in 2001.

Spurs & Burs Common Burdock Goatshead/Puncturevine Houndstongue

Common Burdock Description A biennial or perennial 3 to 8 feet in height, with many flowered heads. Flowering Period June to October. Habitat Fields and pastures. Bad for birds. Uses Plant is a diaphoretic, diuretic, alterative, and depurative. It is used externally in salves or as a wash for burns, skin irritations, and minor wounds.

Goatshead/Puncturevine Tribulus terrestris

Goatshead/Puncturevine Tribulus terrestris Annual, mat forming, trailing stems to 5 feet long Leaves : Opposite, hairy, divided into 4 to 8 pairs of leaflets Oval leaflets 1/4 to 1/2 inch long Stems : Prostrate, trailing, hairy, many branched from root crown Flower: 5 petals, yellow, in leaf axils, to 1/2 inch wide Roots : .

Goatshead/Puncturevine Roots:Fibrous Seeds : Fruit break into 5 sections with 2 to 4 seeds per capsule Capsules tack like structures wtih 2 sharp spines, resembling the head of a goat The burs may injure livestock and are the bane of bicyclists

Houndstongue Cynoglossum officinale

Houndstongue Biennial rough hairy leaves that can be 1-12 inches long and 1-3 inches wide. Flowers can be maroon or white, 1/4" in diameter, bell shaped Sseed pods (nutlets) are covered with hooked spines provide a mechanism for dispersal on clothing and fur The pods are flattened and somewhat heart shaped A common name locally is beggar’s lice. Similar Species: Other plants with sticky seeds, such as nodding beggar’s tick, western sticktight and catchweed bedstraw, can be confused with houndstongue. The shape of the seeds and/or the presence of stout straight spines can distinguish these from houndstongue.

Houndstongue Control Timing: In the rosette or early bolting stage. Target: Prevent seed production. Methods: Mechanical removal is very effective for small infestations, particularly after plants have bolted, when herbicides may not be as effective Rosettes should be killed manually or with herbicides in the spring or fall Plants that are bolting should be removed manually or sprayed as soon as possible Flowering plants should be removed manually and mature flowerheads bagged to prevent seed spread Beware to remove all seeds from clothing, shoes, shoelaces, etc. Status in Mesa County: Found in pastures and roadsides, higher elevations, primarily in higher elevations of eastern Mesa County. Toxicity: Houndstongue is extremely toxic to cattle and horses, less so to sheep. It produces alkaloids that cause liver damage

Houndstongue Toxicity Toxic, pyrrolizidine alkaloids Cause liver cells to stop reproducing Animals may survive for 6 mths after consuming a lethal dose Sheep more resistant to poisoning than cattle or horses.

ID by Photograph Thistles Knapweeds Spurs & Burs

Yellow Flowers Yellow Toadflax Dalmation Toadflax Dyer’s Woad St. Johnswort

Yellow Toadflax ( Linaria vulgaris ) Toadflax shown displacing native flora in the Silverton area. Silverton

Yellow Toadflax ( Linaria vulgaris ) Identification: A creeping perennial that grows to 2 feet tall and is often profusely branched. The flowers look like typical snapdragons, with a pale yellow spur and darker yellow to orange throat. The numerous leaves are linear and pointed. Also called butter and eggs, this is a very persistent plant. Similar Species: Dalmation toadflax has heart-shaped leaves and the stems that are not branched. Many ornamental snapdragons look like toadflax, since it is in the same family. Yellow toadflax has linear leaves. Our native toadflax has blue flowers. .

Yellow Toadflax Control Timing: Before flowering and in the fall. Control target: Prevent seed production and stress root system. Control Methods: This is a very difficult plant to eradicate. The extensive root system must be stressed continually. Mechanical control is often not effective on larger patches, and may spread root pieces. Herbicides are effective but choice of product and control timing is very important. CSU Extension Service Fact Sheet No. 3.114 has more details on control of Dalmation and yellow toadflax. Status in Mesa County: A few small infestations occur at Vega State Park. One small patch was eradicated at the County owned boat take-out on the Gunnison River near Whitewater. A small patch was found on Skipper’s Island in 2001

Dalmation Toadflax Linaria genistifolia ssp. dalmatica

Dalmation Toadflax creeping rooted perennial pale green waxy leaves clasp the stem heart-shaped with a pointed tip 1 – 3 inches long bright yellow "snapdragon-like" flowers with orange spot on the lower lip Flowers are 1 inch long (excluding the 1/2-inch spur), yellow, often tinged with orange or red, Plants flower from midsummer to fall Seeds are produced in a ½-inch pod and are irregularly wing angled.

Dalmation Toadflax introduced as an ornamental from Europe, and is now rapidly invading dry rangeland from 5,000 to 6,500 feet. CONTROL A biological control agent (defoliating moth) is available, but its effectiveness has been very good in Idaho. Well adapted to arid sites can spread rapidly once established Because of its deep, extensive root system, waxy leaf, and heavy seed production, this plant is difficult to manage Dalmatian toadflax may be controlled with Tordon 22K at 2 pt/A sprayed at flowering or in fall

Dyer’s Woad ( Isatis tinctoria )

Dyer’s Woad Member of the Mustard family Non-native winter annual, biennial or short-lived perennial 1 to 4 feet tall Leaves are alternate, simple, petiolate, bluish-green with a whitish vein on the upper surface of the blade Flower has a flat top with yellow petals Fruit is a purplish-brown pod containing one seed. Thick tap root can exceed 5 feet deep It is found in disturbed sites and spreads to range and croplands by seed from late spring to mid-summer. Currently not known in Colorado, Dyers woad is a serious problern in Utah.

St Johnswort Hypericum perforatum

St Johnswort TOXICITY RATING: Low to moderate. ANIMALS AFFECTED: Cattle, sheep, goats, horses, and swine. DANGEROUS PARTS OF PLANT: All parts. CLASS OF SIGNS: Sunburn, skin slough, eye irritation.

White Flowers Field Bindweed Hoary Cress/Whitetop Oxeye Daisy Poison Hemlock

Field Bindweed Creeping perennial from Europe Member of the Morningglory family Reproduces not only by seed but by its horizontal roots as well. The root system and rhizomes are extensive, white in color, and fleshy. Field bindweed stems are prostrate (grows low to the ground) and twining, smooth, and can grow up to 6 feet long Leaves are 1 to 2 inches long and are distinguishable by their arrow-head shape. Flowers are rounded and white to pale pink in color The flowers are about ¾ to 1 inch broad

Field Bindweed Seeds are pearl-shaped, dull, and brown in color One plant can produce anywhere between 30 and 200 seeds, the number produced is variable on environmental conditions. Seed viability can be retained over a period of at least 30 to 40 years in the soil It is extensively found in pastures, lawns, gardens, cultivated fields, waste areas, roadsides, and rangelands Field bindweed thrives on disturbance, especially cultivation and/or overgrazing.

Hoary Cress/Whitetop Cardaria draba perennial mustard extensive root system up to 2 feet tall Plants form a dense, contiguous patch Leaves slightly toothed, upper leaves clasping the stem Numerous small white flowers form a flat-topped flowerhead Seed pods are heart shaped and contain 2 seeds each Similar Species: There are many white flowered mustards in our area. None of them have a dense, flat topped flowerhead, however. Perennial pepperweed, or tall whitetop, is much taller, the flowerheads are less dense than hoary cress, and it blooms in mid to late summer.

Hoary Cress/Whitetop Control Timing: Before or at very early bloom. Target: Prevent seed production. Methods: Herbicide applications can be very effective on hoary cress when applied at the proper time Roundup (glyphosate) applied as a 2% solution at the flower stage has resulted in fairly good control. 2,4-D applied at 3 qts/acre 2 to 3 times per year for 3 years has also been somewhat effective. Noncrop herbicides such as Escort and Telar are probably the most effective as long as some rainfall occurs after application to activate the products Tillage or hand grubbing break up root pieces, which can sprout into new plants No biocontrol agents are available. Status in Mesa County: Widespread in lower elevations of Mesa County but spreading to higher area such as Collbran. Hoary cress and Russian knapweed are the County’s two most abundant noxious weeds.

Oxeye Daisy ( Chrysanthemum leucanthemum )

Oxeye vs Shasta Daisy Has a dipple

Oxeye Daisy ( Chrysanthemum leucanthemum ) Pperennial, white flowered daisy Ccreeping roots Growing to 2 feet tall. Leaves have toothed edges and are 2-5 inches long, getting smaller toward the top of the plant The flowers are 1½ inches in diameter and borne singly on the ends of branches. Similar Species: Shasta daisy is a common ornamental daisy with larger leaves and flowers. Two noxious weeds, scentless and Mayweed chamomile have fern-like leaves and have flowers with an inflated disk (central part of the flower).

Oxeye Daisy Control Timing: In the spring before flowers appear and in the fall. Target: Prevent seed production and stress root system. Methods: Herbicides have been shown to be the most effective control method Mechanical removal may stimulate shoot production from the rhizomatous roots No biocontrol agents are available for this weed. Status in Mesa County: Fairly common in pastures in higher elevations of Mesa County, and in some flowerbeds in lower elevations. Oxeye daisy may still be found for sale as seed, in wildflower seed mixes, or as bedding plants It is illegal to sell this species in Colorado.

Poison Hemlock Conium maculatum L.

Poison Hemlock Conium maculatum L. Member of the Parsnip family It is a biennial introduce from Europe may grow up to 9 feet tall fleshy stout taproot forms a rosette of fern-like, pinnately divided leaves during the first year of growth Stems of poison hemlock have purple spots at all growth stages The white flowers are borne in umbrella shaped cluster, each supported by a stalk. Poison hemlock tends to get started along ditches and waterways, and will occur along the borders of pastures and crop land. All plant parts are poisonous to human sand most domestic livestock According to legend this plant furnished the “cup of death” given to the Greek philosopher Socrates Children have been poisoned by using the hollow stem as a whistle Adults have been poisoned by mistaking the plant for parsley This plant is most common in western Colorado from 5,000 to 9,000 feet.

Poison Hemlock Conium maculatum

Green or Purple Flowers Halogeton Leafy Spurge Jointed Goatgrass Purple Loosestrife

Halogeton Halogeton glomeratus

Halogeton A lethal dose for sheep is about 1 1/2 pounds of green plant Poisoning usually occurs in late fall or early winter, since snow or rain washes out the poison. The poison is not cumulative; a toxic dose must be eaten at one time. The animal becomes dull and cannot move 2 to 4 hours after eating a lethal dose; death may follow within 6 to 10 hours.

Halogeton Mediterranean annual Many erect stems Stems are blue-green in spring, turning yellow or red in fall It reproduces by seed only fleshy, tube-like leaves occur alternately and in bunches along the stem They end abruptly and are tipped with a delicate needle-like spine Tufts of cottony hairs occur at the leaf attachment Flowers are green , inconspicuous and born in the leaf axil. Seeds are of two types: black , which germinate during first growing season after produced, and brown , which are dormant but viable for several years. The plant is toxic to livestock, especially sheep, from high oxalate content, and is easily dispersed by vehicles and road grading equipment.

Halogeton History A native of Russia, it was introduced into the United States in about 1930, and apparently was first identified in Nevada in 1934. It now covers millions of acres in Nevada, Utah, and Idaho, and is found also in Montana, Wyoming, Oregon, and California.

Leafy Spurge Euphorbia esula perennial extensive, deep, creeping rootstocks Roots are dark brown with pink shoot buds Leaves are linear and about 1-1½ inches long Flowers are inconspicuous and green At the base of the true flowers, and emerging before them, are bright yellowish-green bracts that are often mistaken for the flowers It is very important to distinguish these two stages for timing control work Seeds are in a pod, which when dry expels the enclosed seeds up to 15 feet The plants have a milky latex sap which is very toxic. Many plants have milky latex sap don’t not used as a diagnostic tool

Leafy Spurge Control Timing: When bracts are present but before true flowers emerge and in the fall. Target: Prevent seed production and stress root system. Methods: Herbicides are the most effective method of control for leafy spurge Small infestations should be sprayed immediately and repeatedly after allowing regrowth to occur. CSU Extension Fact Sheet No. 3.107 details control methods. Grazing by goats has worked well in some situations Several species of Apthona flea beetles have proved to be very effective in some parts of the country

Leafy Spurge Large infestations are the best candidates for release of biocontrol agents Application of herbicide to the perimeter of a infestation may be necessary to keep the weed from spreading while the beetles establish and build their numbers. Status in Mesa County: Current infestation is in the Plateau Valley area. A small infestation was found in 2001 west of the town of Mesa. A small, dwindling population also occurs in Unaweep Canyon, near the Divide Road turnoff. Toxicity: The milky sap of leafy spurge can cause skin and eye irritation in humans and other animals. It can cause death of livestock. The toxicity remains even after the plants are dried. Caution must be taken when handling this weed

Jointed Goatgrass Aegilops cylindrica Compared to Wheat

Jointed Goatgrass Aegilops cylindrical A native to Asia, is a serious problem in wheat producing areas of the United States It hybridizes with wheat and outcompetes the crop for nutrients and water. Spikes, grassike Shallow, Fiberous root system 3,000 seeds per plant Winter annual

Purple Loosestrife ( Lythrum salicaria )

Purple Loosestrife Perennial with creeping, rhizomatous roots grows up to 10 feet tall A wetland invader, it thrives in moist conditions. Leaves are lance shaped with veins that do not reach the edge of the leaf but parallel the edge The very showy purple to magenta flowers grow on long stalks and have 5-7 petals each The ribbed stems are square or 6-sided Also called purple lythrum Similar Species: An uncommon native loosestrife is shorter and more delicate, with fewer flowers. Gayfeather or blazing star, a native plant, has coarse, more linear leaves that are much narrower than loosestrife. Fireweed, a common native plant, has only 4 petals per flower, a round stem and the flower heads form an elongated triangle.

Purple Loosestrife Control Timing: Before flowering in the spring, and in the fall Mature flowerheads must be removed before the first frost. Target: Prevent seed production and stress root system. Methods: Mechanical control can be effective for small infestations but must be repeated, often for five years or more Timing of herbicide applications is important Spring applications just before flowering, to prevent flowering and seed set Fall applications anytime before a hard freeze, but flowerheads must be removed to prevent spread of seeds Formulations of the herbicides glyphosate and 2,4-D that are labeled for aquatic use are effective An adjuvant or surfactant should be added for better penetration of the chemical Several biocontrol agents are available but establishment is dependant on proper regulation of water levels, and may work better in drier habitats. Status in Mesa County: Large infestations occur along Tiara Creek on the Redlands. Smaller infestations occur along Goat Draw on Redlands Parkway, and on two private properties north of Fruita. Over 70 plants or small infestations were found on the Colorado River in 2001. The spread of the weed to riparian areas along the River are of extreme concern to public lands managers.

Tamarisk or Salt Cedar ( Tamarix parviflora, T. ramosissima )

Tamarisk or Salt Cedar ( Tamarix parviflora, T. ramosissima ) Identification: A small tree or shrub growing up to 20 feet tall, with feathery leaves and tiny purple to white flowers May be deciduous or evergreen, but mostly deciduous in our area. This plant grows in riparian areas and wetlands, often depleting surface water and lowering ground water levels Salt is released from the leaves when they drop in the fall, making the soil in the understory highly alkaline. Can transpire 200 gallons per plant per day and can dry up ponds and streams

Tamarisk Prevent seed production and stress root system. Control methods: Brush hogging, pulling out by the roots, and burning lead to less successful control due to the vigorous regrowth that occurs Cutting down the shrub or tree and painting the stump surface immediately afterward with an herbicide (cut stump treatment) is the most effective control method Herbicide must be applied within 10-15 minutes of cutting to prevent excessive resprouting from the stump Follow up herbicide application is needed to treat sprouts from the root system This usually will only be necessary for 2-4 years All branches and trunk pieces must be removed from the site to prevent sprouting Tamarisk branches touching wet ground have been known to sprout and send down new roots. Chipping or burning the slash is recommended

Tamarisk The cut stump method is best done in the fall or winter after the tamarisk leaves have fallen, to make removal of the slash easier The basal 12-18 inches of the trunks of small plants with smooth bark can be sprayed with herbicide (basal bark treatment) Rough barked plants should get the cut stump treatment Foliar sprays during the growing season must cover the entire leaf surface to be effective and will take 3-4 years of repeated treatment to be successful Two predatory insects have been evaluated and one of them is in the experimental release stage as of 2001. A leaf feeding beetle is currently under experimental release near Pueblo, Colorado, and other sites in the West. Future releases on the Colorado River near Grand Junction are expected. Several years of defoliation by the insects is necessary to kill the plant.

Tamarisk Status in Mesa County: Tamarisk is a plant that is preferred to be controlled, rather than mandatory for control, in Mesa County. It is widespread throughout the county in most riparian zones of permanent and ephemeral streams. Although thought to be a lower elevation plant, tamarisk has been found on Douglas Pass in Garfield County and near McClure Pass in Gunnison County.

Russian Olive Eleagnus angustifolia Fast growing tree 10-25 feet 1-2inch woody thorns Leaves narrow 3-4 inches long, covered with scales that make them look silvery Flowers yellow in clusters Fruits like small olives Can outcompete native vegetation

Anthemis cotula (Mayweed chamomile)

Redroot Pigweed Amaranthus retroflexus

Common Mallow annual to short-lived perennial with prostrate to semi-erect stems, 10 to 60 cm long; long-stalked rounded leaves with heart-shaped base and 5 to 7 broad shallow-toothed lobes; white to pale lilac flowers; seeds in round, flat button-like disk of 12 to 15 smooth nutlets similar to round-leaved mallow ( Malva pusilla ) which has roughened ridges on nutlets White to pale lilac flowers 12 to 15 nutlets in button-like disk

Purslane Portulaca oleracea Prostrate annual

Mediterranean Sage Salvia aethiopis L

Mediterranean Sage Non-poisonous Biennial or short lived perennial Aggressive invader of rangeland 2-3’ tall 7-10” rosette of gray-green wooly leaves Multi branched Stout taproot

Mediterranean Sage White to yellow white flowers in wooly clusters 100,000 seeds per plant

Noxious

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Noxious