2009-03-16_GENERAL DOCUMENTS - C1981015 (2)

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Crosby, Erica From: Oswald, Robert Sent: Monday, March 16, 2009 11:34 AM To: Mathews, Dan Cc: Crosby, Erica Subject: RE: tamarisk Dan and Erica — I am familiar with painting Garlon 4 on cut stumps, and I've heard it's effective. Likewise, painting Garlon 4 on basal bark works well. Another chem used these ways is Remedy (another Dow chem.). BASF makes Arsenal herbicide, used for foliar treatment. I'm assuming that you are not treating these near an open water surface (which would require different chemicals). The problem is the super reserves they have in that deep taproot system. It'll withstand flood, drought, fire, almost anything we can throw at it. Obviously nothing will work with only a one -time treatment, which might not fit your project budget, but something else might have to be omitted if effective treatment is to be done. But maybe digging will work: if they can get everything from the root crown and down a few feet to the larger roots, it might be a good way to kill this young group, or seriously knock it back. In a similar situation as yours, I did see effective elimination of tammies in a bottomland site which had a restricting sandstone layer about 3 ft deep. The roots spread out rather than going deep, so it was possible to dig a lot of them out, with only limited need for follow -up spraying. I'm not sure about the strength of resprouting lateral roots, but possibly if repeated treatments can be made, they could be effective by treating the small plants before they go to seed. Eliminate the seed source then hammer it while it's weakened. This could be by repeated low cutting, and foliar sprays or painted stumps for anything that comes back. These spread by seed so the disturbed surface may be full of seed, and immediately sprout new plants too. Re- populating the surface with the desired vegetation will be important in suppressing a reinfestation. Cool season grasses often make sense in these situations since they sprout and grow early, giving the new weed plants some competition. My literature calls this plant a semi - evergreen, so a foliar spray or bark treatment could be effective if it's green and active now. I can fax you some Dow and BASF literature, if you want. Or check their websites. I'd suggest also checking with the NRCS in Grand Junction, since they have been active in helping manage this scourge there for awhile. If I run across more specifics, I'll pass them along. Good luck! Bob PS — You should check this link too: http: / /www.cwma.org /nx plants /tam.htm From: Mathews, Dan Sent: Monday, March 16, 2009 9:30 AM To: Oswald, Robert Cc: Crosby, Erica Subject: tamarisk Dear Weed Guy, Erica and I seek your guidance regarding treatment of a small patch of tamarisk. At the old Fruita Mine at the base of the Bookcliffs north of Fruita, we have a sediment pond that is dry 99.999% of the time. Over the years, vegetation has established in the pond bottom; a mix of cheatgrass, western wheatgrass, and rabbitbrush. But a few tamarisk seeds blew in over the years too, and there are now 12 to 15 fairly robust, well established tamarisk trees. Erica is coordinating a maintenance project at the site that is in progress this week and next (it is a bond forfeiture coal site, thus my involvement). We don't deal with tamarisk a lot in the coal program, so I thought it would be good to check with you on what might be the best approach. The method I am most familiar with is the cut stump /paint (Garton) method of treatment. The contractor suggested just digging /pulling the individual plants out by the root crown as an alternative to herbicide treatment. I'm wondering if sprouting from severed lateral roots might be a problem if we did the mechanical treatment rather than cut stump herbicidal treatment. We would prefer to minimize any resprouting and need for follow -up treatment, because we'll be using up all of the remaining bond with this project. If we do use herbicide treatment, would a fall (mid- October) treatment be preferable to a treatment this spring (we may extend the project for some follow -up seeding in the fall).