[Partners-IMCWMA] Ludwigia identification

[Tara Athan]

Regarding Ludwigia, I have been in contact with Brenda Grewell of the 
USDA-ARS lab in Davis.  She has offered to come out and give us a field 
training on the different species and subspecies of Ludwigia. The 
earliest she could do this is the week of  August 13th.  The 13th or 
14th is preferred as we could include additional information in a 
Ludwigia project proposal (due date Aug. 15th).
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If you are interested in participating in the Ludwigia identification 
field tutorial, please let me know your availability during the week of 
August 13th.
This will be a full day event starting at Potter Valley and finishing at 
Spring Lake north of Santa Rosa.
Carpooling will be available.  There is no charge for this tutorial.
Those with less available time can join us for part of the tour, but 
must provide their own transportation.
******************************************************************************************
According to Brenda, who has just finished molecular studies of the 
Ludwigia genus, there is a non-native invasive subspecies of L. 
peploides, ssp. montevidensis.  The species L. hexapetala is non-native 
invasive.  L. peploides ssp. peploides.  is at present considered 
native, but it also occurs in South America and is co-occurring with the 
other Ludwigia species that we consider invasive, so there is some doubt 
whether it is really native.

I only saw the water primrose along open banks.  It seems to me that 
increasing canopy cover would be the most effective long-term strategy 
for reducing Ludwigia populations.  I am not sure if nutrient inputs are 
a factor in the upper Russian- certainly they are a factor in the Laguna.

Warner, Peter wrote:
> 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
>
>   


-- 
My e-mail delivery has been unreliable lately, so I am asking for
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OK'ing the return receipt lets me know that my message was delivered.
Thank you.

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