Western Gulf Invasive Weed Issues: a regional perspective

from the USDA-APHIS viewpoint

Dr. C.L. RamseyUSDA-APHIS-PPQ-CPHST

National Weed Management LabFort Collins, CO

Outline

• Invasive weed issues• APHIS-PPQ weed policies• Invasive definitions• Noxious Weed Control and Eradication Act• National Weed Mgt Lab• Biocontrol• Chemical and cultural control• Restoration

Biological pollution

• Approx. 5,000 “escaped” plants in USA

• Florida– 25,000 exotics– 900 “escaped” or 3.6% invasive status

• Cheatgrass reduced fire cycle from 60 – 110 years to 3 – 5 years

• Cogongrass max. fire temp – 458 C

Cogongrass infestationHarvested - July 2000

Aerial photo – Oct 2003Site prep- Velpar ULW 4.7

lb/ac

Cogongrass

Cogongrass – Nov. 2005

Cogongrass – Nov. 2005

Cogongrass – Nov. 2005

Witchweed program• Witchweed (Striga spp.) is a

parasitic weed in corn, sorghum, and other economic crops

• ARS started eradication in 1958 in North and South Carolina

• APHIS - continuing eradication – $175 – $200 million – 439,781 ac. Initially infested– 2, 626 ac. – treat about 1,000

ac/yr– Use ethylene to stimulate

germination of Striga

Texas weed programs

• Orobanche ramosa– Blue flower – 22 counties

– White flower – Karnes county

• Eradication project – about 20 years

• Survey for tropical soda apple– Jasper county – one ranch

• Biocontrol for giant salvinia and hydrilla

Animal Plant Health Inspection Service - APHIS

• Mission – Protect the health and value of American agriculture and natural resources

• Goal 1 – Safeguard the health of animals, plants, and ecosystems in the USA

• Goal 2 – Facilitate safe agricultural trade

• Goal 3 – Ensure the effective and efficient management of programs to achieve APHIS mission

APHIS Weed Policy Goals• Goal 1: Exclude Noxious Weeds of quarantine pest significance

• Goal 2: Detect and evaluate incipient infestations of weeds not known to occur in the U.S.; and detect and delimit introduced Federal Noxious Weeds.

• Goal 3: Control (i.e. suppress, contain, or eradicate) populations of high risk weeds

• Goal 4: Develop and Communicate information - internally and externally to promote noxious weed awareness and action.

• Goal 5. Provide Administrative guidance for the APHIS weed program

Invasive weed lists• Federal Noxious Weeds

– quarantine based, – 72 terrestrial spp., 19 aquatic/wetland spp., 68 parasitic spp.

• State lists:– Texas – 30 total species – Florida – 142 total species

• NatureServ – 382 species– Plan to assess 3,500 species– Ranked by ecological impacts, distribution, spread rate, and

management difficulty– Based on current status – not predictive listing– http://www.natureserve.org/getData/plantData.jsp

Federal Noxious Weed List

• Quarantine pest definition by International Plant Protection Convention (IPPC, 1997)

• A pest of potential economic importance to the area endangered thereby and not yet present there, or present but not yet widely distributed and being officially controlled.

• Weed status - widely distributed, or long history (long lag phase), or uncontrolled or beyond control disqualifies many weeds from being listed

Federal noxious weeds

• Aquatic and wetland weeds: 19 spp. Melaleuca quenquinervia (paperbark tree) Salvinia molesta (giant salvinia)

Parasitic weeds: > 68 spp. Cuscuta spp. (dodders) Orobanche spp. (broomrapes)

Terrestrial weeds: ≥ 71 spp. Crupina vulgaris (common cuprina) Solanum viarum (tropical soda apple)

Non-listed weeds

• Tallow tree – Popcorn tree• Purple loosestrife• Leafy spurge• Canada thistle• Spotted knapweed• Water milfoil• Japanese knotweed• Kudzu

Plant Protection Act (2000)

• Prohibit importation, exportation and interstate trade…to prevent intro of noxious weeds

• Permits needed to transport noxious weeds• Must quarantine biocontrol agents• Publish a noxious weed list• Hold, seize, quarantine, treat, destroy, or dispose

of any plant…deemed to be a plant pest or noxious weed

• Use extraordinary emergency measures for “new or not yet widely distributed” weeds in the USA

Noxious weed definitions• Alien-exotic plants

– Intentional or accidental introduction – Not self-replacing or self reproductive

• Naturalized – Consistent reproduction– Sustainable populations over several life cycles

• Invasive– Naturalized – spread > 100 m in <50 years or 6 m/3 years for

rhizome/stolon spreading plants• Transformers

– Invasive plants– Change character, condition, or nature of ecosystems over a

substantial area

Plant Protection Act definition

• Noxious weed (PPA 7 USC 7702)– Any plant or plant product that can directly or

indirectly injure or cause damage to:

– Crops, livestock, poultry, other agric. interests

– Irrigation

– Navigation

– Natural resources of USA

– Public health

– The environment

Noxious Weed Control and Eradication Act, NWCEA(2004)

• Approved by Congress and signed by President Bush – 10/10/2004

• Under authority of Secretary of Agriculture and delegated to APHIS to implement

• Currently no appropriations

• $7.5 million per year for matching grants

• $7.5 million per year for agreements

Weed Management Entity

• Is recognized by the state• Is established for or has expertise/experience

– Controlling noxious weeds– Increasing public knowledge and education

• May be multi-jurisdictional and multidisciplinary• May include government representative and /or

NGO representatives– Private organizations– Individuals

Program types (2005 -2009)

• Grants

• Funding for weed management entities for control or eradication of noxious weeds

• Federal cost share not more than 50%

• Non-fed share cash or kind

• Project accountability

• Agreements

• Funding for weed management entities for financial and technical assistance for the control or eradication of noxious weeds

• No cost share

• No project accountability

• Rapid response programs

Proposed regulations for NWCEA

• Write up regulations and guidelines for grants and agreements

• Develop selection criteria for control projects and equipment proposals

• Establish regional panels for the selection process

• Selection criteria– Severity of problem

– Likelihood project will resolve problem

– Improve USA capacity to address weed issues

– Provide comprehensive approach

– Other factors

State noxious weed regulations

• Most western states have active noxious weed control at the county level

• Arizona, Nevada, New Mexico, Oklahoma and Texas do not have active control programs

• www.invasivespeciesinfo.gov

• www.nationalplantboard.org

National Weed Mgt Lab people

• Rick Zink – Lab director (pathologist)• Nada Carruthers – entomologist (CA)• Jeff Drake – image analysis (NM)• Richard Hansen – entomologist• Craig Ramsey – weed scientist• Melinda Sullivan – pathologist• Kenna Van – office administrator• Terrence Walters – botanist• Nehalem Breiter - technician

Integrated Pest Management (IPM)

• NWML goal – develop and promote all available weed control and management tools

• Classical biocontrol– GMO vectors– Legume cover crops – allelopathic properties

• Herbicides– Bioherbicides – Bialophos, essential oils

• Fire• Pathogens• Grazing• Cultural - mechanical

What is biological control(aka biocontrol)?

the deliberate use of a weed’snatural enemies to reduce the weed’s

abundance and negative impacts

• Support pre-release surveys for, and research on, classical biocontrol agents

• Field release and redistribution strategies

• Development and application of pest and agent monitoring tools

• Mass rearing of biocontrol agents

• Quarantine processing of biocontrol agents

• Economic analyses of pest and biological control impacts

• Develop ‘target pest lists’ for biocontrol implementation

What PPQ does in biological control projects

• Collaborate in various biocontrol research projects

Labs (CPHST)

Biocontrol sucesses

• Diffuse and spotted

knapweeds

• Leafy spurge

• Purple loosestrife

• Dalmation toadflax

•Giant salvania

• New releases

•Tropical soda apple

• Saltcedar

– 7 northern states

− Above 37th

parallel

− Enters diapause

in states below

Colorado

Current biocontrol projects• Russian knapweed• Hoary cress• Perennial pepperweed• Yellow toadflax• Japanese knotweed• Houndstongue

• Future studies• Cogongrass?

– Country of origin– Related to sugar cane

Biological control of leafy spurge (Euphorbia esula)

Host specificity/Selectivity

• Most time consuming - adaptability

• Primary criteria – single target selectivity – Need a herbicide or insect that kills just the

target weed– Herbivory

• Extensive enough to cause serious injury

• Selective enough to not cause injury to crop or desirable plants

Plant pathogens• Yellow starthistle

– Exotic pathogen – Mediterranean rust fungus Puccinia jaceae– Project initiated in 1978, permitted in 2003 after 25 years– Canada thistle – best candidate for pathogen survey

• Tropical soda apple– Tobacco mild green mosaic virus– Endemic – mechanically transmitted/no vector– Hypersensitive response – whole plant response within hours– Plant death within days

• Cogongrass – Bioherbicide – – Two fungi – Bipolaris sacchari, Drechslera gigantea

• Canada thistle

Biocontrol program

• Advantages– Low cost over long run

– 11:1 benefit cost ratio

– Wide spread (regional, or national) infestations

– Public lands, low income land

– Wide spread approval or acceptance

• Disadvantages– Long term development

– Lack of host specificity

– Crops too related to invasive weed target

– Vectors often in unstable countries

– Place of origin

– Lack of commerical incentives

Chemical control program

• Advantages– Low up front costs

– Systemic

– High availabiltiy

– Medium -high efficacy

– Some selectivity with directed sprays

– Private landowners

– High value lands

• Disadvantages– Broad spectrum

– Low selectivity

– Multi-applications

– High cost – long term

– No control of seedbank

– Off site impacts

– Registration too expensive

Current issues – Herbicide program

• Classic screening studies– Type of herbicide or adjuvant– Rate – Timing

• Weed biology

• Weed ecology

• Restoration

NWML cultural and chemical control

• Three studies in progress– Herbicide and adjuvant study for cogongrass

control– Activated charcoal to alleviate cogongrass

allelopathic effects on loblolly pine– Herbicide and adjuvant study for common

tansy control

Weed biology

• Reliable biological mechanisms that predict invasiveness?

• Growth parameters– Photosynthesis rates, water use efficiency (WUE),

nitrogen use efficency (NUE), leaf size, leaf duration• Soil parameters

– Physical – soil moisture reduction– Chemical – reduction in nutrients or pH, allelopathic

• Reproductive parameters– Seed production, seed longevity,

Invasiveness test

• Microcosm tests• Uniform conditions• Replacement series• Density-dependent

series• Multiple species• Results in one

growing season

Restoration ecology• Seed bank

– delayed dormancy– “escapes” prolific seed production

• Partial rhizome control– Perennials with large rhizome systems– Resprouting

• Soil active herbicides– High rates – long term soil residuals

• Soil degradation– Chemical – saltcedar increases soil salinity– Yellow starthistle – reduces soil moisture– Knapweed – allelopathic root exudates

Depleting seed banks

• Seed inhibition – Commerical products - inhibit seed production

• Induce germination/break dormancy– Plant growth hormones stimulate germination– Ethylene for witchweed germination

• Sterilize soil– Methyl bromide– Soil active herbicides

Improving rhizome control

• Deplete rhizome reserves– Repeated defoliation– Contact herbicides– Grazing, burning, tillage

• Use controlled release herbicides– Long term exposure – Charcoal mixes

• Adjuvants to increase adsorption and translocation– Increase photosynthesis – increase sugar production –

increase sugar translocation into root systems

Restoration issues

• Classical conservation grass mixes• Long-term monitoring of successional rates

– If, or when introduced grass stage may return to native vegetation?

• Biocontrol with plants– Legume cover crops

• Noninvasive, tolerant, highly competitive

– Shade intolerance - high density – shade inhibition• Anti-allelopathic, fast growing, evergreen

Invasive weed websitewww.invasive.org/weeds