2013 Green Industry Training: Weed Law, ID and Management
Learning objectives Understand Nevada weed law and assist clients in complying with the law Use plant biology to design effective weed management strategies Explain the differences between types of herbicides, and know when to use which Identify 13 common weeds of turf and landscapes
What’s a weed?Any plant growing where it’s not wanted.
Weed terminology A weed is a plant growing where it’s not wanted An invasive weed is one that moves in and takes over an area A noxious weed is a legal definition (NRS 555)
What is a “noxious” weed? “any species of plant which is, or is likely to be, •detrimental or •destructive and •difficult to control or eradicate”
How do weeds become listed as “noxious”? • Specific weeds are named as “noxious” in Nevada Law • In order to be listed, there must be some hope of controlling or eradicating the weed
The ListAt the time that the Department lists a species, it willalso give a rating of A, B, or C. These ratings reflect: • the Department’s view of the statewide importance of the noxious weed, • the likelihood that eradication or control efforts would be successful, and • the present distribution of noxious weeds within the state. These lists are found in the Nevada Administrative Code (NAC 555.010).
The TiersA Weeds normally limited in distribution throughout the state; actively excluded from the state and actively eradicated wherever found; actively eradicated from nursery stock dealer premises; control required by the stateB Weeds more widespread throughout the state; actively excluded where possible, actively eradicated from nursery stock dealer premises; control required by the state in areas where populations are not well established or previously unknown to occurC Weeds generally widespread throughout the state; actively eradicated from nursery stock dealer premises; abatement at the discretion of the state quarantine officer
Examples of A, B and C-listed weeds A Listed B Listed C Listed Yellow Diffuse Perennial starthistle knapweed pepperweed Dalmatian Medusahead Puncturevine toadflaxLeafy spurge Musk thistle Saltcedar
NRS CHAPTER 555 INSPECTION AND DESTRUCTION OF NOXIOUS WEEDS NRS 555.150 Every land owner or occupier, whetherprivate, city, county, or federal shall cut,destroy, or eradicate all noxious weeds.
For information on weed law, contact: Robert Little State Weed Specialist NV Dept. of Agriculture 775-353-3673
Growth stages: Seedling Small in size Small root mass Thin plant tissues Water and nutrient requirements small Name this weed!
Growth stages: Vegetative/bolting Rapid growth Rapid uptake of water and nutrients Development of roots, stems and leaves
Growth stages: Seed production Develop flowers and fruit Energy directed toward reproduction
Growth stage: Maturity Top growth slows or stops Little movement of water and nutrients Plant ‘dries down’ and drops seed Annual plants die Perennial plant tops die in preparation for regrowth
Plant life cycles Annual One season for all stages of development Produce foliage, flower seeds, then die Yellow starthistle
Plant life cycles: winter annuals vs. summer annuals Fall moisture Warm soil
Plant life cycles Biennials Require two seasons for completion of life cycle First year: develop roots and low-growing leaves Second year: flowers, sets Musk thistle seed and matures Examples are mullein and musk thistle
Plant life cycles Perennials Live more than two years Will produce foliage, seed, and reach maturity year after year Dandelion Examples are perennial pepperweed and Canada thistle
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
Weeds are symptoms of problems Soil is bare Soil is disturbed regularly Site is not monitored routinely Site is not managed well (watering, mowing, grazing, etc.) Contaminated materials are used Invasive ornamentals are planted Wrong controls are used Etc…
Integrated Weed Management Uses knowledge about how the ecosystem works to find environmentally sound solutions to weed problems.
IWM preferred methods Select plant materials that are well- adapted to our climate and growing conditions so they can compete with weeds Encourage natural controls Manage landscapes correctly to reduce weed problems Etc.
Steps in using IPM on weeds Identify and assess the problem before you do anything – is it bad enough to warrant action? Why do you have a problem? Use all the tools in your toolbox to accomplish the desired result while minimizing undesirable outcomes Consider mechanical, cultural, biological and chemical controls and match them to plant biology
Preventing invasion and spread ofweeds Plant clean, certified weed-free seed Avoid spreading weed seeds with manure Sanitize your equipment prior to moving them from one property to another Plant and maintain desirable plant species Don’t sell or plant invasive or noxious weed species
Preventing invasion and spread ofweeds Monitor plant stock for infestations Minimize soil disturbance and bare ground Apply the appropriate amount of water Avoid driving in weed infested areas
Cultural control Use land management tools that make it difficult for weeds to be successful The key: nurture healthy, successful, desirable competitive vegetation!
Cultural control Aerating Increases the activity of soil microorganisms that decompose thatch Increases water, nutrient and oxygen movement into the soil Improves rooting Enhances infiltration of rainfall or irrigation
Cultural control Fertilizing Only as needed – use soil tests Avoid overfertilization Even applications
Cultural control Mowing turf Mow heights based on species of grass Never remove more than about 1/3rd of the leaf blade Never scalp! Keep blades sharp Clean mower after mowing weeds Don’t mow when soil is wet (compacts)
Mechanical control Hand pulling Hoeing Bulldozing Mowing
Burning and flaming Burning can promote invaders by removing competing vegetation Penetration into soil is limited; does not kill perennial roots Does not disturb the soil but can destroy organic matter May need burn permit Wildfire concerns
Mechanical control Repeated tillage can help reduce seed populations – but disturbs the soil! Mulching (with or without fabrics) – must exclude light; organic mulches can serve as substrates for weed seed germination
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 USDA-ARS
How do you pick the right method? Identify the weed Learn its biology: Annual Biennial Perennial How does it spread?UNCE: www.manageNVpests.infoUC Weed Photo Gallery:http://www.ipm.ucdavis.edu/PMG/weeds_intro.htmlPacific Northwest Weed Management Handbook weed ID:http://weeds.ippc.orst.edu/pnw/weeds?weeds/id/index.html
Consider mechanical control for annuals and biennials Perennial invasive weeds often require the use of herbicides for complete control
How do you pick the right method? How much is there? What are the goals for the site? What special site conditions limit what you can do? What will the client allow and pay for? How fast do you need results?
Herbicides Chemical name Ex: N-(phosphonomethyl)glycine Common name Glyphosate Brand or trade name Roundup, Aquamaster, Weed-b-Gone, Rodeo, etc.
Thirteen steps to follow before usingherbicides: 1. Identify the weeds 2. Determine their life cycle 3. Consider all control alternatives 4. Select the chemical based on effectiveness, safety, and price
Thirteen steps to follow before usingherbicides: 5. Read the label carefully and make sure the herbicide is labeled for the site 6. Determine the best time to apply the chemical 7. Is the chemical restricted-use-only? 8. Consider proximity to water, nearby trees or shrubs, soil composition, tendency to contaminate water supplies
More things to consider!10. Check the weather11. Have you read and do you have a copy of the MSDS?12. Are you applying the appropriate amount by the best method?13. Do you understand all necessary safety requirements, and have you followed them carefully? (gloves, hat, eye protection, long sleeves, long pants, shoes, etc.)
HAZARD = Toxicity x Exposure Risk, or the The capacity of a potential pesticide to cause for injury injury The risk of a pesticide contacting or entering the body
Hazards increase… when mixing and loading the concentrate with a very high single exposure after many exposures over time
How do soil-applied herbicides work? Move into plant with the soil water solution Absorption takes place across the cell walls of the root hairs Non-germinating seeds not affected
How do foliar-applied herbicides work? More difficult than with root absorption Plant cuticle is an effective barrier Must penetrate cuticle, might need wetting agent or oil carrier for herbicide Need uniform application to cover plant (need adequate surface area) Must remain on plant for 6-12 hours Warm humid conditions ideal
Herbicide performance: Temperature 90 Temperature (degrees 80 70 60 50 F) 40 30 20 10 0 0 20 40 60 80 100 Days to control
Using growth stage to time control ofannuals 100 90 80 70 60 50 Percent Control 40 30 20 10 0 Seedling Vegetative Flowering Mature
Using growth stage to time control ofbiennials100 90 80 70 60 50 Percent Control 40 30 20 10 0 Seedling Vegetative Vegetative Flowering Mature Yr 1 Yr 2
Using growth stage to time control ofperennials 100 90 80 70 60 50 Percent Control 40 30 20 10 0 Seedling Bud F. Flower Regrowth
Selective herbicides Used to kill a specific type of weed Broadleaf herbicides--- kill/control broadleaf weeds only i.e. 2,4-D, Curtail, Tordon Grass herbicides--- control only grasses in broadleaf plantings i.e. Poast, Fusilade
Nonselective herbicides Kills most or all of the vegetation in the area covered May be pre- or post-emergent chemicals Example is Roundup ALWAYS READ AND FOLLOW THE LABEL DIRECTIONS!
How do herbicides work? (modes of action) Interfere with or disrupt biochemical or physiological processes in susceptible plants Often affect a specific enzyme or reaction Ex: amino acid synthsis inhibitors – glyphosate, imazapyr, chlorsulfuron growth regulators – 2,4- D, dicamba, clopyralid, aminopyralid, triclopyr Seedling growth inhibitors – trifluralin, dichlobenil
Pre-emergent Post-emergent herbicides herbicides Applied to soil Must be applied to living plant tissueKills plants as they germinate and pick up Little or no soil activity chemical in young rootsMust be watered or tilled inMay have some post- emergent activity
Site of action Contact Herbicides Systemic Herbicides All parts of the plant Applied to plant tissue must be covered to kill Is translocated through entire plant the plant to the roots Usually quick acting Takes time to work! Most often used for Used for perennials annuals
1 drop of a translocated herbicide (2,4-D) placed on a soybean leaf (left) vs. a contact herbicide (right)
Commonly used herbicides Glyphosate Non-selective Systemic Half life ~47 days Readily available to homeowners But…does not kill all weeds Should be applied to young, actively growing weeds
Commonly used herbicides2,4-DBroadleaf selectiveHalf life ~30 daysUsed in weed and feed type products and for weed control in lawnsCan damage adjacent plants if it volatilizes
Commonly used herbicidesMecoprop (MCPP) salt 0.22%2,4-D salt 0.12%Dicamba salt 0.05%Broadleaf selectiveHalf life ~30 days or lessUsed for weed control in lawnsCan damage adjacent plants if it volatilizes (especially dicamba; also mobile in soil)
Commonly used herbicidesTrifluralinPre-emergence herbicideLasts about 3 monthsApplied as a dry granule and watered inMust use it BEFORE seeds sprout
Why do pre-emergence herbicides fail? Label directions not followed – not watered in Applied at the wrong time – plants already sprouted or will sprout after product has broken down (winter vs. summer annuals) Herbicide layer is physically disturbed Wrong product used
Factors that affect movement of the herbicide into the leaf Maximum kill will be obtained under warm, humid conditions with adequate soil moisture Environment influences both the herbicide uptake and how the plant is growing
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.
Granular spreaders Drop (gravity) spreaders pattern= width of spreader uniform coverage or target area Rotary spreaders coverage wider than spreader overlap required for uniformity drift to nontarget areas
Applying granular products Fill equipment on paved surface Make “header” strips around the property Keep material off paved surfaces and out of flower beds Treat property with parallel swaths Use correct overlap Turn off spreader before header strip
Applying granular products Keep spreader level Walk at consistent pace Don’t stop without shutting off spreader Don’t operate backwards Application may change
Spray equipment Traditional spray guns Shower head gun Large droplets Low pressure Spray wand Spray booms
Small-capacity sprayers Used for small areas and spot treatments: Most are hand sprayers Most use compressed air May have a wand, gun, small boom Tank pressure drops as solution is sprayed Minimal agitation -- WPs settle
Application techniques Apply only the amount needed for the desired level of control Apply only where pests are located Don’t allow activities to reduce effectiveness: Rain, not watering-in, etc.
Steps in reducing pesticide risk Choose the right pesticide product and apply it at the right time Read and follow the product label Purchase/mix only what you need Use the product according to label directions Watch the weather Store and dispose of the pesticide properly
Weeds in turf Compete with turf for: Growing space Water Nutrients Sunlight
Weeds are the result of poorA dense, healthy stand of turf is the performance, turfgrass best defense against weed invasions not the cause!
Weeds and site conditions Compacted soil: knotweed, annual bluegrass Wet areas: white clover, annual bluegrass Heavy wear: spurge, knotweed
Steps in a turfgrass IPM programTurf and pest Select corrective knowledge action(s) based on: • Historical data • Turf and pest life Monitor turf cycles regularly • Problem diagnosis • Factors favoring pests • Predetermined Diagnose thresholds problem Evaluate and record results for Take appropriate future management decisions corrective action
IWM for turfgrass Assess site conditions: How turf is used Amount of shade Soil fertility and pH Soil compaction Drainage Presence of excess thatch Current management – mowing height and frequency, aeration, fertilization, etc.
Survey for weeds Find them Identify them How many are there? When do they occur? Certain times of the year, certain weather, etc. How long have they been there? What else is going on at the site?
Common turf weeds Black medic Dallisgrass White clover Johnsongrass Plantains Quackgrass Spotted spurge Nimblewill Common mallow Yarrow Annual poa Dandelion
Control of Annual Weeds Prevent seed set Monitor and find weeds early in their development Use mechanical and cultural methods If herbicides are used, apply to young, actively growing plants Be prepared to deal with pre-existing seed bank
Control of Biennial Weeds Prevent seed set Use mechanical and cultural methods Dig out rosettes in the first year Be prepared to deal with preexisting seed bank
Control of Perennial Weeds Must control existing plant as well as preventing seed set Control is made more difficult by resprouting from roots Herbicides are often needed Make sure you pick the right product for the specific weed
Control of Perennial Weeds Non-selective herbicides kill any type of susceptible vegetation treated (Roundup) Selective herbicides work on a category of plants, such as broadleaf vs. grasses (2,4- D, Fusilade)
Black medic (Medicago lupulina) Looks like clover; is a legume Usually a summer annual Low-growing Hairy leaves and stems Shallow tap root Three leaflets; middle one is on a stalk (petiole) Bright yellow flowers Found where soil is compacted and grass is thin
White clover (Trifolium repens) Creeping perennial Stems branch and root at the stem nodes (stolons); mostly reproduces by seed Shallow fibrous roots Three leaflets joined at central point, may have a whitish crescent at center; hairless White to pale pink flowers on long stalks Common in moist, low-fertility soils
Broadleaf plantain (Plantago lanceolata) Perennial Basal rosette of leaves Leaves are egg-shaped 5 to 7 prominent veins on underside of leaves Flower spikes are leafless Shallow, fibrous roots Found in compacted, wet soil
Buckhorn Plantain (Plantago lanceolata) Forms a rosette Leaves are long and narrow Leaves all grow at the base of the plant and usually have short hairs Leaves have 3 to 5 prominent veins (or ribs) Produces several flowering stalks with a dense 1 – 2-inch-long spike of tiny flowers (“donut”) Has simple or branched tap root More tolerant of drought than broadleaf plantain
Spotted spurge (Chamaesyce maculata L.) Summer annual Grows in flat, dense mats Leaves are opposite and dark green with purple spots Hairy stems and leaves ooze an irritating sap when broken Stems have pinkish color Tiny pinkish flowers in leaf axils
Annual poa (or annual bluegrass, Poa annua)Cool-season grassCommonly confused with similar perennialLight-green, flattened stems that are bent at the baseLeaf blades often crinkled part-way downProlific seederShallow roots form weak sodFound in compacted, moist areas; tolerates some shadeLook for “boat-shaped” leaf tips that curve up like the bow of a boat (Poa)
How much is too much? Depends on aesthetics, how turf will be used, how much damage the pest can cause, what client wants One dandelion may be too many, while for a golf course fairway, 5% white clover may be the threshold Try to discourage homeowners from having completely weed-free monocultures Stress the importance of establishing a reasonable threshold level
Apply controls Match controls to weed species, growth stage, threshold levels, etc. Spot-treat whenever possible Consider safety for the applicator and the residents/users of the turf Nontarget effects? Phytotoxicity? Avoid drift and runoff
Herbicide damage in turf (not tomention the applicator!)
Monitor and keep records How did your controls work? Did weather conditions affect treatment? Include date of treatment, location, product used, rates, formulations, application method, etc.
Flixweed (Descurainia sophia L.) Stem is erect and branched Grows to 2 feet tall Leaves are alternate and highly divided/fernlike Can be finely hairy to almost smooth Flowers are small, pale yellow, in clusters Flower has 4 petals Appears early in spring (winter annual)
Hare Barley (Hordeum leporinum) Grows to 10 inches tall Leaf blades are 1/16 to 2/16 inch wide and smooth to hairy Auricles at base of blade are well- developed, long, narrow, claspi ng and paper thin Produces a spike ½ to 4 inches long with awns ¼ to 1 inch long Commonly called foxtail
Prickly lettuce (Lactuca serriola L.) Annual to biennial that grows 1 to 6 feet tall Stems are hollow and branch into the flowering structure; can be smooth or prickly Leaves are alternate, lobed or entire, twisted at the base and have prickles on edge and on the lower side of the pale midrib; leaves clasp the stem Leaves & stems ooze a milky sap when cut Flower heads are yellow and look like dandelions Has a taproot
Prostrate knotweed (Polygonum arenastrum) Annual to short-lived perennial Grows in a flat, round shape Stems are round, wiry and are enlarged at each joint; highly branched Oval leaves are bluish- green White to green or pinkish flowers are tiny and appear in the axils Does NOT ooze milky sap when stem is broken (vs. spurge) Tough taproot
Redstem Filaree (Erodium cicutarium) Spreads to form a rosette close to ground Stems up to 2 feet long Lobed leaves are fern- like and hairy 5-petaled flowers are “Storksbill” purplish-pink in clusters of 2 or more
Russian thistle (Salsola tragus L.); Barbwire Russian thistle (Salsola paulsenii) Summer annual Commonly called tumbleweed Forms a bushy plant that breaks off and tumbles when dry, spreading seeds Stems usually have red or purple stripes Leaves are alternate; young leaves are long and look like pine needles; later leaves are short and tipped with sharp spines Flowers are tiny, green or pink/red and have no petals Taproot
How to submit a sample for ID Fresh sample: entire plant when possible, bag it and bring it to us To store a sample: refrigerate or press carefully High-quality digital photos
Sue DonaldsonUniversity of Nevada Cooperative Extension 775-784-4848 firstname.lastname@example.org