Transcript Chesapeake Bay Trust

Definitions
• Control – prevention of spread by removing
fruits and limiting vegetative spread
• Eradicate – to completely remove a species
from a location
Topics
•Approaches to control
•Methods of control
– Mechanical
– Chemical (types of herbicides, application
methods
•Selected PNW species
Assessing Invasive Species Threats
At the landscape scale it is
necessary to take two approaches
simultaneously and iteratively:
By invasive species
(Scary species)
By spatial distribution
of invaders and
conservation goals
(Superlative sites)
Two Assessment Approaches
•Species Based
•Site Based
Local control and
management only
Public awareness
typically begins
Introduction
Detection
Plant absent
Scattered
locations
Time
Numerous
locations
At or near biological potential
Control Costs
Acres Infested
Eradication
simple
Eradication unlikely,
intense effort required
Eradication
feasible
Weed Increase Over Time and Control Potential
A = Alhagi
H = Hydrilla
P = Peganum
From: Rejmanek,M. and M. Pitcairn
(2002)
Study Conclusions
• Eradication possible if under 1 hectare
• 1/3 of infestations between 1 and 100
hectares eradicated
• ¼ of those between 101 and 1000 eradicated
• Cost goes up greatly with size
• SO early detection and rapid response is
essential!!!!!
Rejmanek and Pitcairn 2002
Bradley Method
• Work in the least invaded areas first,
working towards invaded areas
• Make minimal disturbance – mulch if
you must disturb the soil
• Let native plant regeneration and your
maintenance ability dictate the rate of
weed removal – never overclear
Manual and Mechanical
• Hand pulling
-can use volunteers
-good for small infestations
-can have low ecological impact
-need to keep equipment clean
-minimize disturbance! Mulch!
-best for annuals or shallow rooted
perennials
Weed Wrench
Manual and Mechanical
•Tillage/hoeing
•Mowing, brush cutting
–Best for species that don’t coppice
–“controls” – does not eradicate except through
repeated use
•Girdling – remove cambium (do not use on
coppicing species, beware creating a hazard
tree!)
•May need to remove stem fragments
Mechanical
•Mulching – bark, hay, cardboard
carpet, etc.
•Flooding/drawdowns
•Fire
Manual or Mechanical
Soil solarization
- kills tissue if around 113-131 degrees F
clear plastic more likely to heat to this
- soil should be moist
- not as good for rhizomatous species
- may alter soil biology and chemistry
Steam or Hot Water
• Hot water breaks
down the
epidermis, the
plant becomes
dehydrated
• Waipuna now promoting
foam – coconut syrup and
water
Infrared Technology
• Heats to 1000oC
• Bursts cells – stops
photosynthesis
• Not good for deeply
rooted species
Grazing
• Can eliminate or encourage
invasive plants
• Can use cattle, goats, sheep,
geese, chickens, ducks, etc.
• Goats eat broadest list of weeds
• 500 sheep = 4/5 acres/day
• Need to fence or pen them in
• May disturb soil, may pass
seeds
Mechanisms - Herbicides
• Inhibit respiration
–Arsenic compounds
–Metallo-organics (also based on arsenics)
–Phenols
• Can be very toxic to mammals
Mechanisms - Herbicides
• Auxins – 2,4,D – causes excess cell
division and overgrowth, good on
broadleaf weeds, non-persisting, low
mammalian toxicity
2,4,5,T – better for woody plants >> has
dioxin = Agent Orange, causes cancer
• Common now: Clopyralid (persists in
compost), picloram, triclopyr (Garlon,
Brush B Gone)
Mechanisms - Herbicides
• Inhibitors of biosynthetic processes
- Cell division – “pre-emergent”
- Nucleic acid or protein synthesis
inhibitors – “pre-emergent”
- Glyphosate – non-selective contact
herbicide, interrupts an amino acid
production pathway not found in animals
– “post-emergent,” Rodeo® used for
aquatics
Adjuvants
• Added to facilitate mixing, effectiveness, or
application of herbicide
• “Surfactants,” “spreader-sticker”
• Usually chemically active, but may be
termed “inert”
• Sometimes included, if not, research to find
recommended one for what you use
Considerations using Herbicides
• Non-target species
• Use best management practices for
handling concentrates
• Follow ALL laws
• Must post treated areas
• Carefully assess site conditions, including
weather
• Likely cannot use volunteers
Methods of Application
• Foliar – spot, boom
• More herbicide
delivered to
non-targets
• May need a
surfactant
Methods of Application
• Basal bark
• 6” band 1’ up stem
• Must mix with
low ester oil
• Best for smaller
shrubs
Methods of Application
• “Hack and squirt”
• Cut every 2 in or
so of stem
• Good for small trees
4-5” dia
• Creates hazard trees!
Methods of Application
• Cut stump “Cut and dab”
• Only need to
treat the cambium
• Apply immediately
after cutting
• Paintsticks handy
• May need to reapply
• Not as good in early spring
Methods of Application
• Injected into cambium
• Can be good for some
herbaceous as well as
woody
• Little human contact with
herbicide
• Buy appropriate injectors
Reed Canary Grass
Phalaris arundinacea
•
•
•
•
•
Rhizomatous grass
Mow 5X +/yr
Mulches (+ cardboard)
Glyphosate (2%)
Shading with plantings
Atlantic/English Ivies
H. helix ‘Pittsburg’
Hedera hibernica ‘Hibernica
H. helix
‘Star’
H. helix ‘Baltica’
Ivies
•
•
•
•
Fast-growing ground cover
Remove vertical vines first
Pull and wad vines on ground
Can use string trimmer followed by
glyphosate or triclopyr
Japanese Knotweed
Fallopia japonica
• Strongly rhizomatous shrub
• Very hard to kill
• 2X/month mowing for
3 years
• Injection – 5 ml of
100% glyphosate
• Triclopyr or glyphosate
Himalayan blackberry
Rubus armeniacus
• Repeated mowing
• Digging
• Cut stump, treat
with triclopyr or
triclopyr + 2,4 - D
Iris pseudacorus
Yellow flag iris
• Freshwater aquatic but
drought resistant
• Seeds and rhizomes
• Dense thickets along shore
• Dig by hand or machine
• Cutting + glyphosate
Scotch broom
Cytisus scoparius
•
•
•
•
Prairies, grasslands
Nitrogen-fixer
Pull or cut stump
Seeds long lived
herb robert, stinky bob
Geranium robertianum
• Herbaceous annual
• Spreads by explosive seeds
• May be allelopathic
• Easy to pull
• Seeds live 5+ yrs
Conclusions
• Start with smallest infestations first
• There are a variety of mechanical and
chemical control methods –combinations
may provide the best control
• For PNW invaders there are a number of
strategies for control that must be tailored to
the biology of the species