Strategies for Control Based on Life Cycle of Invasive Plants Courtney LeClair Invasive Plant Specialist Wisconsin DNR Courtney.leclair@wisconsin.gov
Weed Increase Over Time and Control Potential (1) (2) (3) (4) Prevention or Eradication simple Eradication feasible Eradication unlikely, intense effort required Local control and management only Public awareness typically begins Acres Infested Introduction Detection Control Costs Absent or off-site Few locations Many locations At or near biological potential Time
By the time you are in the control with a management strategy, the cost can be large and the failure rate is often high. Kudzu (Pueraria montana var. lobata)
Hill Mustard 2005.and 2009 Prevention is ALWAYS the best strategy! Early detection is critical for relatively efficient control
Plant Management Steps 1. Plant identification: What is it? Habitat sun vs. shade, wet vs. dry Life form herb, grass, vine, shrub, tree Life cycle annual, biennial, perennial Vulnerable points seedling, rosette, flowering, adult 2. Population size: How much? Select appropriate control tactic: What can I do? Monitor & adapt management over time: What can I do better?
What is the Goal of Management? Compliance with NR 40 Eradication of populations Improve cover of desirable species Improve ecosystem services land Prevention of invasion
Understand the biology of weeds How do they reproduce and spread? Annuals Biennials Simple Perennials Creeping Perennials Annuals Creeping Perennials
Annuals and Biennials Plants grow from seed, produce seed once, and die. Population perpetuated by seed only. Seeds that can live for several years in the soil. Biennials overwinter as a rosette vulnerable stage for control. Goal - Prevent seed formation!
Garlic Mustard Alliaria petiolata Woodlands + shady roadsides
White (Melilotus alba) and Yellow (Melilotus officinalis) Sweet Clover Fields + sunny roadsides Photo: WDNR
Wild Parsnip Pastinaca sativa Photo: www.digitaljournal.com Photo: www.wildliferanger.co.uk Fields + sunny roadsides Photo: WDNR WARNING: Phytophotodermatoxic
Teasels Common Teasel Dipsacus sylvestris Cut-leaved teasel Dipsacus lacinatus Fields + sunny roadsides
Simple Perennials Perennials live to produce seed more than once. May resprout if cut back. Simple perennials do not spread extensively by making new shoots from roots, rhizomes, or runners Goal - Prevent seed formation + kill plants (if possible)
Purple Loosestrife Lythrum salicaria Wetlands + ditches
Spotted knapweed Centaurea maculosa Miketyler Jr. K.Holmes-GLIFWC
Dame s Rocket Hesperis matronalis Woodlands, grasslands, roadsides
Creeping or Spreading Perennials In general, more problematic than simple perennials Spread and reproduce extensively from seed and by making new shoots from roots, rhizomes, or runners Root fragments can start new plants Goal - Prevent seed formation + kill roots (if possible)
Canada Thistle Cirsium arvense Photo: Colorado State University Extension Photo: WDNR Photo: Colorado State University Extension Fields + sunny roadsides Photo: Colorado State University Extension
Productivity of an unmanaged invasive plant Canada thistle (creeping perennial) 1 root fragment planted in a soil box and let grow for a little over one year Richard Zollinger, North Dakota State University
Shoot and root growth next year 644 ft of roots and 336 ft of shoots Phil Westra, Colorado State University
Photo: WDNR Leafy Spurge Euphorbia esula Fields + sunny roadsides Photo: WDNR Photo: WDNR
Japanese Knotweed Polygonum cuspidatum Sun and shade, wet to dry Problematic on shorelines
Grasses Two of our worst are very large and dominant perennial grasses. Very high growth rates Form very dense sods that exclude all other species over time Can spread by seed, but mostly by roots and many buds at plant base Goal - Prevent seed formation, weaken tops by repeated mowing + kill roots through repeated efforts
Reed Canary Grass Phalaris arundinacea Fields + sunny roadsides Photo: WDNR Photo: WDNR
Common Reed Grass Phragmites australis Wetlands, shores, ditches
Invasive Shrubs Prolific fruits dispersed by birds Leaf out early and hold their leaves late Especially invaders of woodlands Many form thickets Most resprout if cut, unless stump-treated Goal Minimize seed formation, + remove tops and kill roots
Common Buckthorn Rhamnus cathartica Glossy Buckthorn Rhamnus frangula Free Picasa photo Photo: Chicago Botanic Gardens Forests, edges, backslopes
Eurasian bush honeysuckles Lonicera tatarica, morrowii, x bella Photo: Richard Old, XID Services, Inc. Bugwood.org Photo: WDNR Forests, edges, backslopes Kennith J. Sytsma
Autumn Olive Elaeagnus umbellata Forests, edges, backslopes
Invasive Vines Most are spread widely by birds that eat their prolific fruits. Grow along ground or climb trees, fenceposts, etc. Most resprout if cut, unless stump-treated Difficult to mow Goal Remove tops and kill roots
Oriental bittersweet Celastrus orbiculatus Forests, edges, fencelines TNC TNC
Manipulation of the environment Competition/prevention in establishment Desirable plants compete with weeds Established plants are better competitors Limit disturbance Most weed species need disturbance to establish Prescribed burn Promotes some competitive species If timed properly, can kill young plants/seedlings
Mowing Can effectively reduce seed production Specific to weed species Annuals + Biennials Reduce population sizes if timed correctly and conducted for several years Perennials Typically need additional management to reduce populations
Herbicide Broadcast applications Pre-emergent emergent Post-emergent Directed methods Spot treatment Basal bark application Cut stump Wick Timing specific Nonselective herbicide Will injure any plant it contacts Selective herbicide Won t t harm grasses Won t t harm broadleafs Random selectivity Persistence No residual (hours -11 day) Short residual (days - week) Long lasting (months - year)
Prevention Wash equipment to remove soil and plant parts after used in an infested area Use weed free materials Hay and straw Gravel, fill, top soil Compost Keep adjacent areas weed free
Cleaning suggestions Remove plant parts, seeds, and dirt that may contain invasive species from anything transported off an infested site Also includes gear, clothing, and animals Tools to clean with Pressure washer Pressurized air Brush Washing stations