injection of herbicides into rhizomes of knotweeds and other invasive species
DESCRIPTION
We ran trials on this method for a few years as did other organizations and individuals. Ultimately, we did not find its efficacy to outweigh the labor involved. Therefore, Green Shoots decided not to launch the product. We have however had real success with foliar applications using our Green Shoots Foam Herbicide Dispenser. John Lampe gave a presentation on that system at the 2014 Upper Midwest Invasive Species Conference: http://www.slideshare.net/johnlampe/how-to-kill-i.TRANSCRIPT
1
Injection of Herbicides into Rhizomes of Knotweeds and Other Invasive Species
John LampeGreen Shoots, LLC
Saint Paul, Minnesota
Upper Midwest Invasive Species ConferenceOctober 29-31
La Crosse, Wisconsin
Knotweed – Why Control?
• It is listed by the World Conservation Union as one of the world's 100 worst invasive species.
• This is not precise ranking but does show recognition of how problematic species is.
Outline of Talk
• Background on Knotweed
• Current Chemical Control Methods
• How Can Our Methods be Improved to:– Reduce quantity of herbicide used– Reduce off-target harm
Common Species of Knotweed
• Japanese knotweed (Polygonum cuspidatum)
• Giant knotweed (Polygonum sachalinense)
• Bohemian knotweed (Polygonum x bohemicum) – hybrid
Identification
Good source: Prather TS, Miller TW, Robins SS, Knotweed shrubs: identification, biology, and management, Pacific Northwest Extension Publication 2009
Knotweed Colony
Knotweed Leaves
Photo Credit: Steve Manning, Invasive Plant Control, Bugwood.com
• Dark green leaves• Un-toothed• alternate
Knotweed Stems - Young
Knotweed Stem - Dry
Photo Credit: James H. Miller, USDA Forest Service, Bugwood.com
• Hollow internodes• Septum separating• Up to 2 in. dia.
Knotweed Rhizome
Rhizome
Knotweed Spreads by
• Rhizome extension – up to 6 to 8 feet a year
• Distribution of plant parts– Rhizome pieces – as small as 0.7 g (Brock 1992)– Node pieces
• Seeds – not major source in WA. (Miller 2005)
Knotweed Badness
• Riparian areas especially vulnerable
• Out-compete other plants => monoculture– Loss of trees– Changes in soil fertility– Erosion along streambeds and stream banks
Knotweed Monoculture
Photo Credit: Justin Knabe, Minnesota DOT
Knotweed Rhizome Extension
Photo Credit: Popplewell Associates, York, UK
Knotweed Rhizome Extension
Knotweed Rhizome Extension
Non-Chemical Control
• Not practical except with small infestations
• Danger of vegetative spread
• See King County, Best Management Practices (2008)
Chemical Control Methods
• Foliar
• Stem injection
• Cut stem
Key Herbicides
• Glyphosate – aquatic label
• Triclopyr – aquatic label; only foliar
• Imazapyr – aquatic label; only foliar
Knotweed Rhizome Tough to Kill!
Key Problem: older parts of rhizome and dormantbuds are weak sinks. (Bashtanova et al. 2009.)
Knotweed Rhizome – Tough to Kill!
Foliar
• Advantages– Fastest application method– Decent control: 81%. (Miller 2005)
• Disadvantages– Off-target harm: Avg. injury: 68%. (Miller 2005)– Hard to treat tall plants
Stem Injection
Stem Injection
• Use hypodermic or special injector• Inject up to 5 ml into stem• Between 1st and 2nd node above ground
Stem Injection
• Advantages– Precision– No stem disposal– Efficacy; Avg control: 88% (Miller 2005)
• Disadvantages– Time-consuming– Id of treated stems– Non-target injury: 26% (Miller 2005)
Biggest Disadvantage of Stem Injection
• Requires 5 ml of herbicide per aerial shoot– Equivalent to frill application on 10 to 15 inch
woody stem. AquaMaster Label.• Aerial shoot density averages about 9
stems/m2. Brock 2007.• 45 ml of 54% a.i. glyphosate per square
meter.• May explain 26% non-target injury found by
Miller.
Cut Stem
• Cut stem 5 to 10 inches off ground• Immediately pour up to 3 ml into hollow of
stem
Pouring Herbicide into Cut Stem
Cut Stem
• Advantages– Low cost equipment– Control? (Miller did not test)
• Disadvantages– Time-consuming– Disposal of green aerial shoots– Amount of herbicide used
Stem Wipe
• Inconsistent Results (Miller 2005)
Follow-Up Applications
• Washington State Dept Agriculture:
– Data show “significant decrease in knotweed following six years of annual treatments.
– However, knotweed is still present at each monitoring site.” (Statewide Knotweed Control Program; 2010 Progress Report)
How Can Methods Be Improved?
• Reduce repeat applications
• Reduce quantity of herbicide used
• Reduce off-target harm
We Have Been Trying Several Methods
Rhizome Injection
Rhizome and Roots
Rhizome Injection
Needle reaches to below-ground Internode
Herbicide Used
• AquaMaster – glyphosate; 54% a.i.
• Dose at 2ml
• Well below AquaMaster label rate for hollow stem injections: 5 ml
Inserting Needle into Cut, Dead Stem
Injecting into Rhizome through Cut Stem
Inserting Needle into Bent Live Stem
Results?
Ongoing Rhizome Injections
• Winter and early spring injections did not produce results
• Late spring injections show promise
• Currently doing tests – late summer and Fall
Other New Methods Being Explored
Cut, Bend, and . . .
Treat with Foam Herbicide
Munch, Bend, and . . .
Treat with Foam
Tromp, Wait, and . .
Treat Regrowth with Foliar Applied
Low Volume Foam Herbicide
Bend and Immediately Treat . . .
Stems and . . .
Foliage
Potential Advantages of Foliar Methods
• Not treating tall plants – reduces off-target harm
• Treating with Foam Herbicide– Improves adhesion– Reduces drift
• Late season – should improve treatment success
Rhizome Injection Methods
• Less time consuming
• Less herbicide
• Injecting into rhizome – will this improve treatment success?
Bent Stem Wiping Methods
• Exposing vascular tissue
• Foam herbicide sticks to stem
• Uses a lot less herbicide
58
Green Shoots
John Lampe – contact:• [email protected] • 651-245-4682 (cell)Website: www.greenshootsonline.com • Email or call for copy of
presentation