[MAIPC] Fallopia japonica

Sat Sep 3 07:35:00 PDT 2016

Good morning Judy,

Your fear that rhizomes or other plant pieces could break up and form new infestations in the river is very well justified. This species is notorious for aggressively spreading to new areas along waterways and floodplains. However, I do not know the salinity range the species can tolerate. My understanding is that Japanese knotweed rarely sets seed, as we discussed at the July meeting of the Invasive Species Council (MISC).  Treating with Rodeo is a very good choice for these habitats. If exclusively treating cut-stump, surfactant wouldn't be added, but if treating foliar, you would add the non-ionic surfactant. Indicator dye would be good to add to ensure all plants are treated, but dye can get messy.

A good read from the USDA Natural Resource Conservation Service (NRCS):
https://efotg.sc.egov.usda.gov/references/public/mn/797japaneseknotweed.pdf

"Japanese knotweed control should take a watershed perspective, from the headwaters downstream, as the primary dispersal mechanism is by water (both seeds and plant fragments). Control of knotweed must be well thought out due to the extensive root system and sprouting ability as well as the site limitations. Knotweed frequently infests riparian areas near streams which add complexity to any control plan."

Pen State also has a great guide: http://plantscience.psu.edu/research/projects/vegetative-management/publications/roadside-vegetative-mangement-factsheets/5managing-knotweed-on-roadsides

>From the Home and Garden Information Center, University of Maryland Extension:

Japanese Knotweed/Mexican Bamboo (Polygonum cuspidatum) The hollow shoots of this Japanese native have knotty bamboo-like joints. Flowers are greenish-white. Aggressive roots, 2-3 feet deep, enable it to form exclusive clumps, 6-8 feet tall, in sun or shade. CONTROL: Before late-summer flowering, cut at least 3 times per season and treat freshly cut stumps and/or foliage with glyphosate. Black plastic mulch will kill.

Hopefully a biological control will come at some point...

Take care,

Michael Ellis
Non-Native Invasive Plant Management Field Coordinator
Park Ranger Office, Natural and Historical Resources Division
The Maryland-National Capital Park and Planning Commission

240-429-5042

From: MAIPC <maipc-bounces at lists.maipc.org<mailto:maipc-bounces at lists.maipc.org>> on behalf of Marc Imlay <ialm at erols.com<mailto:ialm at erols.com>>
Date: Saturday, September 3, 2016 at 7:51 AM
To: Judy Fulton <jfulton5 at GMAIL.COM<mailto:jfulton5 at GMAIL.COM>>, 'MAIPC' <maipc at lists.maipc.org<mailto:maipc at lists.maipc.org>>
Subject: Re: [MAIPC] Fallopia japonica

We apply rodeo plus non-ionic surfactant in the little cup that forms at the base when sawed their at ground level. We use 20% glyphosate. We get 100% success with this method.

Marc Imlay, PhD, Chair, MAIPC Biological control working Group Conservation biologist,
Park Ranger Office, Non-native Invasive Plant Control coordinator. Marc.Imlay at pgparks.com<mailto:Marc.Imlay at pgparks.com>
(301) 442-5657 cell  Natural and Historical Resources Division
The  Maryland-National   Capital   Park  and Planning Commission

From: MAIPC [mailto:maipc-bounces at lists.maipc.org] On Behalf Of Judy Fulton
Sent: Friday, September 02, 2016 12:00 PM
To: MAIPC <maipc at lists.maipc.org<mailto:maipc at lists.maipc.org>>
Subject: [MAIPC] Fallopia japonica

I was recently sent the attached two photos of what looks like Fallopia japonica (aka Polygonum cuspidatum and Reynoutria japonica), which were taken in May. Apparently, the homeowners, whose property borders Back River in Baltimore County near Rock Creek Park, Maryland, are quite pleased with their decision to plant "Japanese bamboo" to reduce erosion.

I'm concerned because Fallopia japonica can live in salt environments, such as salt marshes. I've been informed that the mouth of Back River is at the southern edge of the fresh water zone of the Chesapeake Bay with average salinity of 6 ppt, but salinity can range from <1 ppt to 10 ppt depending on weather conditions.  I'm assuming that the pieces of rhizomes that might break off in a major storm could survive in Back River to colonize other areas, especially if the storm reduced the salinity in the river. Does anyone know if this is correct? Also, would the seeds remain viable if they were transported to another location by Back River?

If the homeowners were convinced to remove their Fallopia japonica, what would be the best way to eradicate it so near the water? Something like Rodeo plus a non-ionic surfactant?

Thanks for your advice.

Judy
____________________________________________

Judith P. Fulton
Consultant, University of Maryland Extension
Master Gardener, University of Maryland Extension
Chair, Maryland Invasive Species Council Subcommittee on Invasives Lists
410-337-3701
jfulton5 at gmail.com<mailto:jfulton5 at gmail.com>

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