What to Do About Weeds Developed by: Susan Donaldson University of Nevada Cooperative Extension UNCE, Reno, Nev.

Topics to be covered  What is a weed?  Why worry about weeds in pastures and landscapes?  How weeds are regulated  Weed biology  Factors that lead to plant invasion  Preventing invasion and spread of weeds  Identifying weeds  Control - mechanical, cultural, biological, and chemical  Common weeds in your area

What’s a weed? UNCE, Reno, Nev.

USDA-ARS

MSU Extension Service

Wow! The wide open continent of North America offers great potential for advancement. Today: America, The Land of Opportunity 1900: Arrived from Europe I think I’ll settle down here. This looks like a good place to raise a family Way to go! UNCE, Reno, Nev.

Invasive weed spread UNCE, Reno, Nev.

Weed impacts  Decreased grazing potential  Economic losses from refusals of hay shipments  Decreased crop yields  Cost of control UNCE, Reno, Nev.

Weed impacts  Decreased property values  Loss of wildlife and fish habitat  Impairment of wetland functions  Increased erosion  Toxicity UNCE, Reno, Nev.

Weed impacts  Increased habitat for vermin such as mosquitoes  Impacts to recreation  Altered fire regimes  Lowering of water table depths  Etc…. RGJ reader, Reno, Nev.

How are weeds regulated, and what are your legal responsibilities?

The three D’s of noxious weeds  Damaging to the economy or environment  Difficult to control  Tend to Dominate a site

How weeds grow

Dicot (Broadleaf) Two true leaves Broad leaves have net-like veins Coarse tap root Monocot (Grass) One seed leaf Parallel veins Fibrous roots

Plant life cycles  Annual  One season for all stages of development  Produce foliage, flower seeds, then die Yellow starthistle UNCE, Reno, Nev.

Plant life cycles  Summer annuals  Live from spring to fall  Examples are foxtail, pigweed  Winter annuals  Germinate in fall and winter  Examples are cheatgrass and mustard

Plant life cycles  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 mullein and musk thistle UNCE, Reno, Nev. Musk thistle

Plant life cycles  Perennials  Live more than two years  Will produce foliage, seed, and reach maturity year after year  Examples are perennial pepperweed and Canada thistle UNCE, Reno, Nev. Dandelion

Reproduction  Annuals and biennials  Seed  Seed bank

Reproduction  Perennials  Simple: Reproduce by seed and pieces of root, such as dandelions  Bulbous: Produce seed, bulblets and bulbs, such as wild onion  Creeping: Produce seeds, rhizomes (underground stems), stolons (above ground stems), or creeping roots

Creeping roots of perennial pepperweed UNCE, Reno, Nev.

Identifying weeds  Don’t be afraid to ask for help!

Plant parts for grass identification NRCS, Bozeman, Mont.

Plant parts for broadleaf identification NRCS, Bozeman, Mont.

Have you correctly identified the weed? Tumble mustard Spotted knapweed Perennial sowthistle

Are you really sure??? Yellow starthistle Dandelion

How do weeds ensure their success?  They take advantage of the characteristics of sites, including:  Exposed or disturbed soil (grading road shoulders)  Turfgrass, range, pasture or groundcover that is weakened by disease, pests, or poor management  Places where a desired species is not well- adapted to its environment

How do weeds ensure their success?  They are very competitive  Grow well in spite of interference from other plants UNCE, Reno, Nev.

How do weeds ensure their success?  They are persistent  Will return year after year  Reproduce vigorously  Spread seeds effectively UNCE, Reno, Nev.

How do weeds ensure their success?  They are harmful  Can alter the site they grow in by accumulating salts, changing water table depths, increasing erosion, increasing wildfire frequency, etc. UNCE, Reno, Nev.

How do weeds spread?  Natural means  Wind  Water  Animals UNCE, Reno, Nev.

How are we spreading weeds?  Irrigation  Roadside shoulder work  Construction/ fill dirt  Vehicles  Tillage  Contaminated seed or feed  Livestock management UNCE, Reno, Nev.

What can we do? Practice Integrated Pest Management (IPM) IPM is a sustainable approach to managing pests that combines biological, cultural, physical and chemical tools in a way that minimizes economic, health, and environmental risks

UC Davis Hand removal of weeds Sticky traps and other physical traps

Components of an IPM program  Planning  Setting action thresholds  Monitoring and detection  Identification  Implementation  Evaluation ridall.com

IPM tools for weed management (IWM)  Prevention  Eradication  Mechanical controls  Cultural controls  Biological controls  Chemical controls

Building a weed management plan CONSIDER THE:  Identity of the weed  Biology of the weed  Extent of the problem  Environmental conditions of the site  Ultimate objectives for the site  Most economical solution UNCE, Reno, Nev.

Method 1 of IWM: Prevent the invasion and spread of weeds  Plant clean, weed-free seed  Avoid spreading weed seeds with manure  Sanitize tillage and harvest equipment prior to moving them from one field to another  Plant and maintain desirable plant species  Consider crop rotation to slow weed spread

 Minimize soil disturbance and bare ground  Don’t overgraze pastures  Apply the appropriate amount of water  Avoid driving in weed- infested areas Method 1 of IWM: Prevent the invasion and spread of weeds USDA NRCS

Method 1 of IWM: Prevent the invasion and spread of weeds  Don’t transport flowering plants that you cannot identify  Pull small patches before seed is formed  Carefully remove weeds that have flowered  Report new infestations

Reporting  State Weed Specialist, Department of Agriculture  Your local Cooperative Extension office

Method 2 of IWM: 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  Only feasible for small, new invasions  Must revegetate the area

Method 3 of IWM: Mechanical Control  Cultivation  Hoeing  Bulldozing  Burning  Hand pulling  Mowing UNCE, Reno, Nev. CSUCE

Method 3 of IWM: Mechanical control  Mulching  Solarizing (use clear plastic for maximum affect)  Repeated tillage can help reduce seed populations UNCE, Reno, Nev.

Method 4 of IWM: Cultural control  Cultural control involves using land management tools that make it difficult for weeds to be successful  Shading  Water and nutrient management  Correct seeding rates

Method 5 of IWM: Biological control  Biological control is the use of one organism to suppress another  Can reduce pesticide use  Agents can be free or purchased  Can effectively and economically suppress pests  Does not eradicate a weed UNCE, Reno, Nev.

Method 5 of IWM: Biological control  Characteristics of successful biocontrol agents:  Prolific  Thrive and become widespread in all habitats and climates that the pest weed occupies.  Good colonizers of new areas. Leaf eating beetle (Diorhabda elongata) on tamarisk NDOA

Tamarisk biocontrol NDOA

Method 6 of IWM: Chemical control UNCE, Reno, Nev. CSUCE

Manage pastures to minimize weeds USDA NRCS Herbicides Prevention Proper fertility and species Dense vegetation, no bare spots Managed grazing

Pesticides: an all-inclusive term covering all “cides”  Herbicide  Fungicide  Insecticide  Rodenticide  …

Naming herbicides  Chemical name  N-(phosphonomethyl)glycine  Common name  Glyphosate  Trade or brand name  RoundUp , Aquamaster , Glypro , Rodeo , etc.  Brand  Monsanto

To spray or not to spray?

To spray or not to spray? Consider:  The goals for the site  The site conditions  Accessibility  Proximity to surface water  Depth to groundwater  Presence of rare species  Etc.

Herbicide properties  Effectiveness against target species  Behavior in the environment  Toxicity  Safety

Twelve steps to follow before using herbicides: 1.Identify the weeds 2.Determine their life cycles 3.Consider all control alternatives 4.Select the chemical based on effectiveness, safety, and price

Twelve steps to follow before using herbicides: 5.Read the label carefully and make sure the herbicide is labeled for the pest and the site 6.Determine the best time to apply the chemical 7.Is the chemical restricted-use- only?

Twelve steps to follow before using herbicides: 8.Consider proximity to water, nearby trees or shrubs, soil composition, tendency to contaminate water supplies 9.Check the weather 10.Have you read and do you have a copy of the MSDS?

More things to consider! 11.Are you applying the appropriate amount by the best method? 12.Do you understand all necessary safety requirements, and have you followed them carefully? (gloves, hat, eye protection, long sleeves, long pants, shoes, etc.)

Personal protective equipment MU Extension

What’s wrong with this picture?

Pesticide toxicity  Caution  Warning  Danger Less toxic More toxic

More things to consider! Have you kept mixing and storage areas away from waterbodies and wells? UNCE, Reno, Nev.

Contain chemicals when mixing  Don’t mix on the same patch of soil time after time  Try to mix on an impervious surface  Be prepared for spills

Cleaning containers  Check label for directions  Follow triple-rinse procedure  Apply rinsate on areas as indicated on the label

NEVER mix or rinse pesticides in the street! UNCE, Reno, Nev.

Safety tips  Each time you use a pesticide, read the directions!  Never eat, drink, or smoke while applying pesticides or before cleaning up.  After applying pesticides, remove your clothes and wash them; then thoroughly wash hands, face, and body.

Safety tips  Work outdoors with good light and ventilation when mixing or loading pesticides.  Never mix or apply pesticides on windy days.  If you splash or spill a pesticide while mixing or loading, stop immediately. Remove contaminated clothing and wash thoroughly. Control, contain, then clean up the spill.

How do herbicides work?  Interfere with or disrupt biochemical or physiological processes in susceptible plants  Often affect a specific enzyme or reaction  Example: amino acid inhibitors - glyphosate

Chemical control  Selective  Kills only a specific plant or type of plant  Most common types are broadleaf vs. grass USDA NRCS ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!

Chemical control  Examples of selective herbicides  2,4-D (Weed-b-Gone , Weedar 64  )  picloram (Tordon , retricted use, persistent)  chlorsulfuron (Telar , Glean  ; may be used pre- emergence)  triclopyr (Garlon 3A  ) ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!

Nonselective herbicides  Kills most or all of the vegetation in the area covered  May be pre-mergent or postemergent chemicals ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!

Chemical control  Examples of nonselective herbicides  glyphosate (Roundup  )  imazapyr (Arsenal  ; use pre-emergence or postemergence; has a long residual in high pH soil) ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!

Herbicide Action Preemergent herbicides  Applied to soil  Kills plants as they germinate and pick up chemical in young roots  Must be watered or tilled in  May have some post- emergent activity Postemergent herbicides  Must be applied to living plant tissue  Little or no soil activity

Site of action Contact Herbicide  All parts of the plant must be covered to kill entire plant  Usually quick acting  Most often used for annuals Systemic Herbicide  Applied to plant tissue  Is translocated through the plant to the roots  Takes time to work  Used for perennials

Herbicide formulation  How a product is packaged  Active ingredients (to kill target plant)  Other ingredients (aid in application, stability, absorption, inert ingredients)  Liquid and dry formulations

Spray adjuvants and surfactants  Added to spray mixes to facilitate the mixing, application, or effectiveness of the herbicide  Many herbicides require or suggest surfactant use  Some formulations already include adjuvants (ex.: Roundup Pro  )

Adjuvant types  Activators (enhance activity)  Surfactants (nonionic, etc. – most widely used)  Oil adjuvants (petroleum oil concentrates)  Utility adjuvants  Wetting agents (spreaders)  Dyes  Drift/foaming control agents  pH buffers  Water conditioners  Etc.

Methods of application  Foliar application  Spot, wick, boom, aerial  Basal bark/stump application  Soil application What’s he doing wrong?

Weed treatment in riparian areas  Select the most effective treatment methods for the site  If herbicides are used, be sure the label allows application adjacent to or in the water  Consider wipe application to minimize spray drift UNCE, Reno, Nev.

RESTRICTED USE PESTICIDE (GROUND AND SURFACE WATER CONCERNS) THIS PRODUCT IS A RESTRICTED-USE HERBICIDE DUE TO GROUND AND SURFACE WATER CONCERNS. USERS MUST READ AND FOLLOW ALL PRECAUTIONARY STATEMENTS AND INSTRUCTIONS FOR USE IN ORDER TO MINIMIZE POTENTIAL FOR ATRAZINE TO REACH GROUND AND SURFACE WATER. GROUNDWATER ADVISORY Atrazine can travel (seep or leach) through soil and can enter groundwater which may be used as drinking water. Atrazine has been found in groundwater. Users are advised not to apply atrazine to sand and loamy sand soils where the water table (groundwater) is close to the surface and where these soils are very permeable, I.e. well drained. MIXING/LOADING INSTRUCTIONS This product may not be mixed/loaded, or used within 50 ft. of all wells, including abandoned wells, drainage wells, and sink holes. Operations that involve mixing, loading, rinsing, or washing of this product into or from pesticide handling or application equipment or containers within 50 ft. of any well are prohibited, unless conducted on an impervious pad constructed to withstand the weight of the heaviest load that may be positioned on or moved across the pad. This product may not be mixed or loaded within 50 ft. of intermittent streams and rivers, natural or impounded lakes and reservoirs. This product may not be applied aerially or by ground within 66 ft. of the points where field surface water runoff enters perennial or intermittent streams and rivers or within 200 ft. around natural or impounded lakes and reservoirs. If this product is applied to highly erodible land, the 66-ft. buffer or setback from runoff entry points must be planted to crop, seeded with grass or other suitable crop. Follow all label directions Groundwater advisory A 50-foot distance from well and water bodies is required

More to think about: Are the conditions right for spraying?  Weather  Heat  Humidity  Dust  Wet plants

Timing is everything!  Early season  Late pre-season  Season (bud or early flowering)  Post-frost

ALWAYS ALWAYS read the label and follow its directions

 Sunflower family (Asteraceae)  Perennial  Dioecious  Flowers white to purple  Reproduction primarily vegetative through creeping roots, some seed Canada thistle (Cirsium arvense)

Controls Mechanical: Mowing can provide effective control if conducted at one month intervals Biological: One insect species available, but only provides limited control Fire: Controlled spring burns will slow spread Chemical: Clopyralid + 2,4-D (Curtail  ), picloram (Tordon  ), aminopyralid (Milestone  ), chlorsulfuron (Telar  ), 2,4-D Canada thistle (Cirsium arvense)

Common crupina (Crupina vulgaris)  Sunflower family (asteraceae)  Winter annual  Also called bearded creeper  Resembles knapweeds  Grows to 4 feet tall  Urn-shaped purple flowers  Reproduces by seed Douglas Barbe, CDFA Ray Gill, CDFA

Controls Mechanical: Hand pull, hoe, or till before flowering; monitor site Biological: No insects available; grazing animals will avoid it Chemical: Picloram (Tordon  ), clopyralid, triclopyr, 2,4-D + dicamba Common crupina (Crupina vulgaris)

 Buckwheat family (Polygonaceae)  Tap-rooted perennial  Dark green alternate leaves  Small green flowers turn reddish brown at maturity  Reproduces by seed (30,000 seeds/plant) or by root cuttings kaweahoaks.com Curly dock (Rumex crispus)

Controls Mechanical: Prevent seed set; hand pull or cultivate; mow to prevent flowering Biological: Grazing not effective; no biocontrol agents available Cultural: Fertilize crops as needed Chemical: 2,4-D or dicamba (Banvel  ) before flower elongation; glyphosate (Roundup  ) at early heading; aminopyralid (Milestone  ), sulfometuron (Oust  ), clopyralid (Transline  ) Curly dock (Rumex crispus)

 Figwort family (Scrophulariaceae)  Short-lived perennial  Taproot  Up to 5 feet tall  Bright yellow flowers with a spur  Heart-shaped leaves  Spreads by roots and seed Dalmatian toadflax (Linaria genistifolia spp. dalmatica) UNCE, Reno, Nev.

Dalmatian toadflax (Linaria genistifolia spp. dalmatica) Controls Mechanical: Hand-pull small plants, making sure to remove lateral roots completely; mechanical controls are not recommended for medium to large stands Biological: Graze with sheep or goats to eliminate seedlings; will not kill mature plants; eight insects in use in the U.S. Fire: Burning does not kill the roots and may stimulate shoot growth Chemical: Hybridization complicates chemical control; try picloram (Tordon  ), picloram + 2,4-D; chlorsulfuron (Telar  ), dicamba (Banvel  ) ; imazapic (Plateau  )

 Sunflower family (Asteraceae)  Biennial/short-lived perennial  Reproduces by seed only  Flowers white to pale purple  Bracts surrounding flowers have four or five lateral spines with one long terminal spine UNCE, Reno, Nev. Diffuse knapweed (Centaurea diffusa) UNCE, Reno, Nev.

Controls Mechanical: Cutting, mowing, pulling prior to seed set provides reduction, but not elimination Biological: Five insect species Fire: Severe fire will effectively kill the plant Chemical: Picloram (Tordon  ), clopyralid (Transline  ), aminopyralid (Milestone  ), imazapic (Plateau  ) 2,4-D, glyphosate (Roundup  ) Diffuse knapweed (Centaurea diffusa) UNCE, Reno, Nev.

Dodder (Cuscuta spp.)  Morningglory family (Convolvulaceae)  Yellow to orange to white twining plant  Parasitic  Especially problematic on alfalfa  Numerous small white to pink flowers  Annual; produces seed CSU CDFA USU

Dodder (Cuscuta spp.) Controls: Mechanical: Mow, burn, remove infested material. Destroy host plants. Use frequent cultivation. Cultural: Eliminate host plants Biological: None Chemical: Use Roundup  (glyphosate) to kill host plant; try imazethapyr (Pursuit  ), pendimethalin (Prowl  ) or pronamide (Kerb  )

Downy brome (Bromus tectorum L.) UNCE, Reno, Nev.  Grass family (Poaceae)  Winter annual  Smooth erect stem; visible ligule with frayed margin  Reproduces by seed (up to one billion/acre)  Seeds are long and flat with an awn as long as the seed  Mature plants turn purple to brown as they dry  Increases fire frequency UNCE, Reno, Nev.

Controls Mechanical: Mow prior to seed set and repeat as needed; hand pull small infestations Biological: None available Cultural: Graze to prevent seed set in spring; reseed with competitive vegetation Chemical: Glyphosate (Roundup  ) applied in spring; imazapic (Plateau  ); preemergent, such as Treflan  or Oust , in fall or early spring Downy brome (Bromus tectorum L.)

Purdue Utah Weeds Dyer’s woad (Isatis tinctoria)  Mustard family (Brassicaceae)  Winter annual, biennial, or short- lived perennial  Bluish-green alternate leaves  Yellow flowers in clusters with a flat top  Seeds produced in seed pods near mid-summer

Controls Mechanical: Hand-grub in rosette stage or during flowering; mowing results in resprouting Biological: Eurasian rust fungus stunts growth Chemical: 2,4-D, chlorsulfuron (Telar  ), metsufuron (Escort  ), imazapic (Plateau  ) Dyer’s woad (Isatis tinctoria)

Eurasian watermilfoil (Myriophyllum spicatum)  Water Milfoil family (Haloragaceae)  Submersed, rooted aquatic vine  7 to 10 feet long  Perennial  Leaves have 12 to 21 leaflet pairs vs. fewer than 12 for native milfoil  Leaves collapse when removed from water  Spreads by seeds and plant parts nativeEWMF UNCE, Reno, Nev. WA Dept. of Ecology

Controls Mechanical: Dredging, mowing, hand removal, shading, bottom barriers. Will spread from small plant fragments. Cultural: Practice prevention; monitor boats for contamination. Biological: Milfoil weevil (not released in Nev.) Chemical: 2,4-D, simazine, fluridone (Sonar  ; maintain 10 to 20 ppb for 6 weeks), triclopyr (Renovate 3  ) Eurasian watermilfoil (Myriophyllum spicatum)

Field bindweed (Convolvulus arvensis)  Flowers are trumpet- shaped and white to pinkish  Reproduces by seeds which remain viable for up to 50 years and from rootstocks  Morningglory family (Convolvulaceae)  Perennial  Alternate, arrowhead- shaped leaves on climbing stems UNCE, Reno, Nev.

Controls Mechanical: Pull vine to interrupt seed set; till every two to three weeks during the growing season for two to three years Biological: Two moths are available Cultural: Practice early detection and control of small populations Chemical: 2,4-D or dicamba (Banvel  ), picloram (Tordon  ), metsulfuron (Escort  ), imazapic (Plateau  ), glyphosate (Roundup  ) Field bindweed (Convolvulus arvensis)

Purdue Field horsetail (Equisetum arvense)  Horsetail family (Equisetaceae)  Perennial  Aerial stems  Underground tuber- bearing rootstocks  Stems are hollow and jointed  Does not flower; reproduces by spores

Controls Mechanical: Prevent spore formation by mowing or cutting; mulch; practice deep cultivation Biological: None Fire: Rhizomes survive even hot fires Chemical: Dichlobenil (Casoron  ), amitrole, MCPA, chlorsulfuron (Telar  ) Field horsetail (Equisetum arvense)

UNCE, Reno, Nev. Foxtail barley (Hordeum jubatum)  Grass family (Poaceae)  Perennial bunchgrass  Leaf blades 1 to 6 inches long  Flower heads break into seven-awned clusters of three spikelets when mature  Reproduces by seed

Controls Mechanical: Mow to prevent seed set Biological: Graze early in the year Cultural: Use good site-management techniques; avoid overgrazing and bare ground conditions Chemical: Glyphosate (Roundup  ) or preemergent herbicides Foxtail barley (Hordeum jubatum)

UNCE, Reno, Nev. Hoary cress (Cardaria draba)  Mustard family (Brassicaceae)  Perennial  Small white flowers in flat clusters  Reproduces by seed and creeping roots

Controls Mechanical: Cultivation every 21 days beginning early in spring and continuing until no additional shoots or seedlings appear; repeated disking Biological: None known Cultural: Plant competitive vegetation Chemical: 2,4-D, imazapic (Plateau  ), chlorsulfuron (Telar  ), or metsulfuron (Escort  ) Hoary cress (Cardaria draba)

Houndstongue (Cynoglossum officinale)  Borage family (Boraginaceae)  Biennial or short-lived perennial  Grows 1 to 4 feet tall  Reddish-purple flowers have 5 petals  Leaves are hairy and tongue-shaped  Produces a single flowering stem  Reproduces by prickly seed agri.state.mt.us NRCS, Bozeman, Mont.

Controls Mechanical: Pull or dig; mow second year plants during flowering but before seed maturation Biological: Currently being studied Chemical: Picloram (Tordon  ), 2,4-D, metsulfuron (Escort  ). chlorsulfuron (Telar  ), imazapic (Plateau  ) Houndstongue (Cynoglossum officinale)

Johnsongrass (Sorghum halepense)  Grass family (Poaceae)  Most often perennial; winter kill in cold climates  Grows 3 to 10 feet tall  Leaves have prominent, white midvein  Large, open reddish panicles, up to 1 foot long  Spreads by seed and rhizome invasive.org

Controls Mechanical: Pull or dig; repeated, close mowing can be effective; try fall plowing to expose rhizomes to freezing temperatures Biological: Managed grazing Chemical: Glyphosate (Roundup  ), sethoxydim (Poast  ), fluazifop (Fusilade DX  ), imazapic (Plateau  ) with methylated seed oil at late boot or bloom stage Johnsongrass (Sorghum halepense)

Klamathweed (aka St. John’s wort) (Hypericum perforatum)  St Johnswort family (Clusiaceae)  Perennial  1 to 3 feet tall  Transparent dots on oblong leaves  Yellow, five- petaled flowers  Spreads by seed and creeping stems UNCE, Reno, Nev. John Randall, TNC

Klamathweed (Hypericum perforatum) Control: Mechanical: Repeated hand pulling on new or small infestations Biological: Insects are available (Klamathweed beetle, Chrysolina quadrigemina); weed is toxic to horses Cultural: Revegetate infested sites after control Chemical: Apply glyphosate to actively growing plants; 2,4-D to new seedlings (repeat applications needed); metsulfuron (Escort®) in pastures

Kochia (Kochia scoparia)  Goosefoot family (Chenopodiaceae)  Annual  1 to 8 feet tall  Numerous narrow, hairy leaves  When dry, breaks off and tumbles UNCE, Reno, Nev.

Kochia (Kochia scoparia) Control: Mechanical: Mow just before seed set, cut, or pull to interrupt seed production. Timing is important. Cultural: Avoid soil disturbance Biological: None Chemical: Most broadleaf herbicides are effective, as is glyphosate

CSUCE tncweeds.ucdavis.edu Leafy spurge (Euphorbia esula)  Spurge family (Euphorbiaceae)  Perennial  Reproduces by seed and extensive lateral root system  Flowers yellowish-green, small, and surrounded by paired, heart-shaped yellowish-green bracts

Controls Mechanical: Cutting, mowing, tilling, pulling ineffective Biological: Thirteen insect species available; sheep and goat grazing provides temporary control Fire: Ineffective due to regeneration from root Chemical: Picloram (Tordon  ), 2,4-D, glyphosate (Roundup  ), amitrole, dicamba, imazapic (Plateau  ) Leafy spurge (Euphorbia esula)

Meadow hawkweed (Hieracium caespitosum)  Sunflower family (Asteraceae)  Yellow flowers look similar to a dandelion flower, but are slightly smaller and in clusters  Perennial  Grows 1 to 3 feet tall  Single stalk and leaves are hairy  Stems & leaves exude milky sap when broken  Spreads by root, stolon, and seed Tom Forney, Oregon Dept. of Ag. E. Bella, USDA Forest Service.

Controls Mechanical: Not recommended; digging, mowing, grazing or tillage stimulate growth of new plants from fragmented roots, stolons and rhizomes Biological: None Chemical: 2,4-D, dicamba, clopyralid (Transline®), triclopyr & clopyralid (Redeem R&P®), clopyralid & 2,4-D (Curtail®), picloram (Tordon®), aminopyralid (Milestone®) Meadow hawkweed (Hieracium caespitosum)

King Co. Weed CDFA Mediterranean sage (Salvia aethopsis)  Mint family (Lamiaceae)  Biennial to perennial  First year’s leaves are grayish and wooly; plant bolts in second season with multi-branched stems  Taproot  Flowers are yellowish- white  Aromatic  Reproduces by seed spread as the plant tumbles

Controls Mechanical: Cut the taproot 2 to 3 inches below ground; mow repeatedly to reduce seed production; tillage Biological: Sage crown/root weevil Cultural: Maintain healthy plant cover; avoid overgrazing Chemical: Picloram (Tordon 22K  ), clopyralid (Transline  ), 2,4-D Mediterranean sage (Salvia aethopsis)

Medusahead (Taeniatherum caput-medusae)  Grass family (Poaceae)  Winter annual  Spike inflorence, awns 1 to 4 inches long, twisted, minutely barbed  Reproduces by seed  Will outcompete cheatgrass UNCE, Reno, Nev.

Controls Mechanical: Plowing/disking reduces stands by 50%-95% if conducted after germination Biological: No insects; graze early in the season Fire: Slow, hot fires can reduce a stand by 60%- 95% Chemical: Glyphosate (Roundup  ), imazapic (Plateau  ), sulfometuron methyl (Oust  ) Medusahead (Taeniatherum caput-medusae)

Musk thistle (Carduus nutans)  Sunflower family (Asteraceae)  Biennial  Winged stem  Leaves have prominent, light- colored midrib  Flowers deep rose, violet, or purple  Reproduces by seed  Average seed production 10,000 seeds/plant  Seed can be viable for 10 years UNCE, Reno, Nev.

Controls Mechanical: Repeated mowing, hand pulling, or cutting can stop spread Biological: Thistle head weevil; thistle crown weevil Chemical: 2,4-D, dicamba (Banvel  ), glyphosate (Roundup  ), clopyralid (Transline  ), picloram (Tordon  ), chlorsulfuron (Telar  ), or aminopyralid (Milestone  ) Musk thistle (Carduus nutans)

Oxeye daisy (Chrysanthemum leucanthemum)  Sunflower family (Asteraceae)  Perennial  Grows 1 to 3 feet tall  Spreads by seed; 26,000 seeds from a single plant!  Smaller flower than ornamental Shasta daisy UNCE, Reno, Nev.

Oxeye daisy (Chrysanthemum leucanthemum) Controls Mechanical: Hand pull or dig; remove entire root mass and repeat Cultural: Don’t plant as an ornamental; read labels on seed mixes Chemical: Aminopyralid (Milestone  ), clopyralid (Transline  ), glyphosate on actively growing plants (repeat)

Perennial sowthistle (Sonchus arvensis)  Sunflower family (Asteraceae)  Perennial  Grows 2 to 4+ feet tall  Erect, hollow stems with milky sap  Leaves have prickly margins  Yellow flowers  Seeds spread by wind; also spreads from creeping roots OSU J. DiTomaso, UCD NDSU

Perennial sowthistle (Sonchus arvensis) Controls Mechanical: Cultivate below 30 cm when plants are in rosette stage; till repeatedly Biological: Insects and nematodes; cattle and sheep will graze the weed Fire: Kills top growth but does not kill the roots Chemical: 2,4-D, clopyralid + 2,4-D (Curtail  ), triclopyr + clopyralid (Redeem R&P  ), aminopyralid (Milestone  ), amitrole

Perennial pepperweed (Lepidium latifolium)  Mustard family (Brassicaceae)  Perennial  Prefers moist, alkaline soils  Lanceolate leaves; upper leaves are smaller  White flowers produced in June to September  Reproduces by seed and creeping roots UNCE, Reno, Nev.

Controls Mechanical: Avoid mowing, cultivation and plowing; try repeated hand-pulling for 4+ years Biological: Research being done on insects; graze intensively using sheep or goats; will not kill the weed, however Chemical: 2,4-D amine; metsulfuron (Escort  ) or chlorsulfuron (Telar  ); imazapyr (Arsenal, Habitat  ), imazapic (Plateau  ) Perennial pepperweed (Lepidium latifolium)

Plumeless thistle (Carduus acanthoides)  Sunflower family (Asteraceae)  Winter annual or biennial  Mature plants are 1 to 4 feet tall  Hairs on underside of leaf  Leaf-like spines on stem  Single flower at end of stem  Purple flower heads 1 to 2 inches in diameter  Thick, fleshy taproot  Spreads by seeds OR Dept. of Agriculture WI DNR

Controls Mechanical: Pull or dig plants, removing top 2 inches of root; mow closely twice per season; do not let seeds form Biological: Thistle head weevil; thistle crown weevil Chemical: 2,4-D, dicamba, glyphosate, clopyralid (Transline  ), picloram (Tordon  ), chlorsulfuron (Telar  ), or aminopyralid (Milestone  ) Plumeless thistle (Carduus acanthoides)

Purdue Poison hemlock (Conium maculatum)  Parsley family (Apiaceae)  Biennial; may grow to 9 feet tall  Tiny white flowers form an umbel  Distinctive purple splotches on hollow stems  Tap-rooted  Reproduces by seed  Highly poisonous, especially taproot

Controls Mechanical: Mow prior to seed production; hand pull while wearing gloves Biological: Hemlock moth (defoliates) Chemical: 2,4-D, MCPA, picloram (Tordon  ), glyphosate (Roundup  ) or metsulfuron (Escort  ); use water-labeled formulation in riparian area Poison hemlock (Conium maculatum)

Puncturevine (Tribulus terrestris)  Caltrop family (Zygophyllaceae)  Annual  Reproduces by seed  Can grow 15+ feet across  Yellow flowers occur every few inches along stems  Fruits sharp pointed, five segments, each section contains 2 to 4 seeds UNCE, Reno, Nev.

Controls Mechanical: Dig, hoe, till, hand pull prior to seed production; mulch 4 to 6 inches deep Biological: Two effective insect species available Chemical: 2,4-D, glyphosate (Roundup , etc.), imazapic (Plateau  ), chlorsulfuron (Telar  ) preemergents Puncturevine (Tribulus terrestris)

Purple starthistle (Centaurea calcitrapa)  Sunflower family (Asteraceae)  Biennial, rarely annual  Flowers purple with one inch spines  Reproduces by seed  Seed can be viable for many years  Seedheads break off easily CDFA King Co. Weed

Controls Mechanical: Hand pulling can remove small infestations, mowing alone is ineffective Biological: Five insect species available; repeated grazing (cattle/sheep) can be an effective control Fire: May provide control if burned prior to seed set for multiple years Chemical: 2,4-D, picloram (Tordon  ), clopyralid (Transline  ), triclopyr + clopyralid (Redeem R&P  ), dicamba Purple starthistle (Centaurea calcitrapa)

CSUCE TNC Weeds Purple loosestrife (Lythrum salicaria)  Loosestrife family (Lythraceae)  Perennial  Flowers purple on spikes; stems are square  Reproduces by seed and adventitious roots  Average seed production is 2.5 million seeds/plant  Seed can be viable for several years

Controls Mechanical: Dig young plants, taking care to remove all root fragments Biological: Several insects available Chemical: Glyphosate in water-labeled formulation (Rodeo  ), triclopyr (Renovate  ), imazapyr (Habitat  ), metsulfuron (Escort  ) Purple loosestrife (Lythrum salicaria)

Quackgrass (Elytrigia repens L.)  Grass family (Poaceae)  Perennial  1 to 3 feet tall  Leaf blades ¼ to ½ inch wide, flat, and pointed  Upper surface of leaf blade may be hairy  Leaves often constricted near tips  Florets are awnless, or have short, straight awns  Reproduces by seeds and spreading, sharp-pointed rhizomes Univ. of Illinois

Controls Mechanical: For small infestations, pull or dig; try repeated plowing, mowing, or disking followed by herbicide application Biological: No insects; graze prior to other controls Chemical: Glyphosate (Roundup  ), fluazifop (Fusilade DX  ), bromacil + diuron (Krovar  ), amitrole, pronamide (Kerb  ), dichlobenil (Casoron  ) Quackgrass (Elytrigia repens L.)

UNCE, Reno, Nev. Russian knapweed (Acroptilon repens)  Sunflower family (Asteraceae)  Perennial  Flowers are lavender to pink to white  Flowers from June to August  Reproduces by seeds and creeping roots

Controls Mechanical: Cutting or mowing prior to seed set provides reduction, but not elimination Biological: One insect species Chemical: Picloram (Tordon  ), clopyralid (Transline  ), aminopyralid (Milestone  ), imazapic (Plateau  ), 2,4-D, glyphosate (Roundup  ) Russian knapweed (Acroptilon repens)

Russian thistle (Salsola tragus)  Goosefoot family (Chenopodiaceae)  Annual  Bushy, ½ foot to 3 feet tall, with many branches  Red or green flowers  Reproduces by seed; seed spreads as plants break off and tumble, hence name “tumbleweed”  Spreads by seeds UNCE, Reno, Nev.

Russian thistle (Salsola spp.) Controls Mechanical: Mow or hoe at early stages of growth; cultivate; pull seedlings Cultural: Prevent soil disturbance (not a very competitive plant) Biological: None Chemical: Most broadleaf herbicides are effective, as is glyphosate as a spot spray; apply herbicides to early growth; use preemergents from March to May

Rush skeletonweed (Chondrilla juncea)  Sunflower family (Asteraceae)  Tap-rooted perennial  Grows 1 to 4 feet tall  Look for downwardly- bent coarse hairs on the base of stems  Stems above are smooth  Leaves are almost invisible except in rosette  Flowers are yellow and less than one inch wide  Spreads by seed and roots J. DiTomaso, UC Davis

Rush skeletonweed (Chondrilla juncea) Controls Mechanical: Hand-pull small plants repeatedly when young; do not mow or cultivate Biological: A rust and two insects are available; try sheep grazing Fire: Burning probably will not kill the roots and may stimulate shoot growth Chemical: Picloram (Tordon  ), clopyralid (Transline  ), MCPA, 2,4-D

Scotch thistle (Onopordum acanthium)  Sunflower family (Asteraceae)  Biennial  Grows to 8 feet tall  Winged stems  Leaves are large, hairy, and have a grayish-green, cottony look  Prominent mid- vein  Flowers pale purple to violet  Spreads by seed USU Extension UNCE, Reno, Nev.

Controls Mechanical: Pull, dig or remove top 2 inches of crown before seed set; mowing does not kill the plant and it may still flower Biological: No insect species available, cattle and sheep will not graze scotch thistle Cultural: Plant competitive grasses; avoid overgrazing Chemical: 2,4-D, dicamba, glyphosate, clopyralid (Transline  ), picloram (Tordon  ), chlorsulfuron (Telar  ), or aminopyralid (Milestone  ) Scotch thistle (Onopordum acanthium)

CSUCE tncweeds.ucdavis.edu Spotted knapweed (Centaurea maculosa)  Sunflower family (Asteraceae)  Short-lived perennial, rarely biennial  Reproduces by seed  Flowers pinkish-purple, rarely cream  Floral bracts tipped with dark comb-like fringe UNCE, Reno, Nev.

Controls Mechanical: Cutting or mowing, prior to seed set provides reduction, but not elimination Biological: Thirteen insect species; cattle, sheep or goat grazing useful in reduction Fire: Variable effects, depending on severity of fire Chemical: Picloram (Tordon  ), clopyralid (Transline  ), aminopyralid (Milestone  ), imazapic (Plateau  ) 2,4-D, glyphosate (Roundup  ) Spotted knapweed (Centaurea maculosa)

Sulfur cinquefoil (Potentilla recta)  Rose family (Rosaceae)  Perennial  1 to 1½ feet tall  Hairy stems  Toothed leaflets  Light yellow flowers with five notched petals  Spreads by seed and shoots J. DiTomaso, UC Davis King Co., WA

Controls Mechanical: Dig, hand-pull or till repeatedly, prior to seed production; mowing results in prostrate growth form Biological: Several insects are currently being investigated Chemical: Picloram (Tordon  ), metsulfuron- methyl (Escort  ), aminopyralid (Milestone  ), 2,4-D Sulfur cinquefoil (Potentilla recta)

Tamarisk (Tamarix ramosissima, others)  Tamarisk family (Tamericaceae)  Perennial  Shrubby tree 5 to 20 feet tall  Reddish-brown bark and pink to white flowers  Leaves are small and scale-like  Reproduces by seed and adventitious roots UNCE, Reno, Nev.

Controls Mechanical: Burn prior to herbicide application to prepare the site; will sprout if cut; dig out with bulldozer (not very effective, as root fragments sprout) Biological: Leaf-eating beetle has been released in Nevada and Utah Chemical: Imazapyr (Arsenal  ), triclopyr (Garlon  or Renovate  ), glyphosate in water-labeled formulation (Rodeo  ) Tamarisk (Tamarix ramosissima, others)

Yellow starthistle (Centaurea solstitialis)  Sunflower family (Asteraceae)  Winter annual  Flowers yellow with 1 inch spines  Reproduces by seed  Average seed production is 1,000 seeds/plant  Seed can be viable for several years UNCE, Rneo, Nev.

Controls Mechanical: Hand pulling can remove small infestations, mowing alone is ineffective Biological: Five insect species available; repeated grazing (cattle/sheep) can be an effective control Fire: May provide control if burned prior to seed set for multiple years Chemical: 2,4-D, picloram (Tordon  ), clopyralid (Transline  ), aminopyralid (Milestone  ),. chlorsulfuron (Telar  ), triclopyr + clopyralid (Redeem R&P  ) Yellow starthistle (Centaurea solstitialis)

 Figwort family (Scrophulariaceae)  Perennial  Taproot  1 to 2 feet tall  Narrow leaves  Bright yellow flowers with bearded orange throat  Spreads by roots and seed Yellow toadflax (Linaria vulgaris)

Controls Mechanical: Hand-pull small plants, making sure to remove lateral roots completely; mechanical controls are not recommended for medium to large stands Biological: Graze with sheep to eliminate seedlings; will not kill mature plants; eight insects in use in the U.S. Chemical: Hybridization complicates chemical control; picloram (Tordon  ), picloram + 2,4-D, chlorsulfuron (Telar  ), dicamba, imazapic (Plateau  ), glyphosate (Roundup  or Rodeo , depending on the presence of surface water)

Now what?  Go home and inventory the weeds on your property  Identify the weeds  Why do you have a weed problem? What can you change about the way you manage your property that will decrease the weed population?

Then...  Determine the most appropriate controls based on biology of the weed and your plans for the site  Fill out your weed management plan activity sheet  Start working!  Monitor your property for weeds on a continual basis

Successful weed management requires constant vigilance and care on the part of the land manager. CSUCE