[Partners-IMCWMA] Russian river riparian weed survey

[Warner, Peter]

One item that may or may not have been considered for water-primrose
(Ludwigia sp.): the taxonomy of the geneus and its native species and
non-native,invasive species is not clear.  I haven't kept up on the
status of genetic studies, and knowing the identity of an invasive plant
would seem to be fairly critical before prescribing treatment.  I know
that in the Laguna de Santa Rosa, at least earlier in that project's
history, what was thought to be a non-native invader turned out to be L.
peploides, a native taxon.  The Jepson Interchange website has no
information on the status of systematics in the genus, which is
troubling since many ecologists with whom I've discussed this genus cite
its confusing taxonomy.

Also, the genus responds positively to nutrient inputs, so managing the
weed without managing factors in its reproductive and ecological success
would seem futile.

Peter J. Warner
Environmental Scientist
California Department of Parks & Recreation
Mendocino District
P. O. Box 440
Mendocino, CA 95460
(707) 937-9176
Fax: (707) 937-2953
pwarn at parks.ca.gov
-----Original Message-----
From: partners-bounces at imcwma.org [mailto:partners-bounces at imcwma.org]
On Behalf Of Tara Athan
Sent: Thursday, July 26, 2007 11:36 AM
To: IMCWMA partners
Subject: [Partners-IMCWMA] Russian river riparian weed survey

A survey was conducted yesterday of the Russian along the reach from 
Hopland to Squaw Rock. There is good news and bad news.
Good news- we observed NO red sesbania, other than the original 
population in the Caltrans ditch along 175.
Bad news- we observed LOTS of water primrose, 46 individual patches, 
ranging in size from 1m to 30m.

Conclusion: Red sesbania is a viable eradication target, Water primrose 
is not.

Suggestion:
1. we request funding for follow-up treatment of the Red sesbania patch 
(it will be treated this season), with a 1:1 match from in-kind 
contributions
 >  Caltrans (mowing the blackberry around the sesbania to give access),
 > Mendo Co. Ag (herbicide treatment)
 > volunteer surveyors to check for outliers in the riparian area.
Additional general matching funds from WMA activities, such as meeting 
attendance, will help boost the match ratio.
I don't have an exact figure yet for the funds required for this, but I 
estimate it to be less than $5000 per year.

2. we should consider a project to address water primrose from a 
"top-down" approach, as a regional collaboration that augments the 
control programs of the Sonoma County Water Agency and Laguna de Santa 
Rosa.  I am trying to get information from those projects now.

Tara

-- 
Tara Athan
Coordinator, Inland Mendocino Cooperative Weed Management Area
coord at imcwma.org
707-485-1198
PO Box 415
Redwood Valley, CA 95470


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