PERMFILE111966

• Permit No: M1977129
• IBM Index Class Name: Permit File
• Doc Date: 8/17/1998
• From: JUDITH M SIROTA
• To: WHITEWATER BUILDING MATERIALS CORP
• Media Type: D
• Archive: No

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•
Judith M. Sirota
Horticulture Pest fa Weed Inspector
P. O. Box 20000
Grand Ju Colorado 81502-5028
Phone: [phone] or [phone]
Fax: [phone] - Emait: pestinsp®aol.com
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14 August 1998
Roy Jones
Whitewater Building Materials
P.O. Box 1769
Grand Junction, CO 81502
Dear Roy,
Permit #: M-77-129
Thank you for calling me on Tuesday, August 11, to talk about Russian knapweed control in gravel pits
operated by Whitewater Building Materials. This letter is to review our conversation and the
recommendations Imade to'you concerning knapweed control.
You mentioned that you have been using Rodeo plus an aquatic 2,4-D, but were having limited results.
Our current "best management practice" for Russian knapweed is to spray it in the fall when the plants are
drawing nutrients into the root system for winter storage. The herbicide is drawn down with the flow and can
work on the root system. Although this is more effective than spraying in the pre-flower stage, it will still
take more than one year of application to get good control.
I mentioned that you should consider using Curtail (or any product containing clopyralid) in the fall at
the rate of 2-3 quarts per acre. A surfactant such as X-77 can be added to the tank to enhance the activity of
the herbicide. The recommended rate of surfactant is 1 quart per 100 gallons of solution. Curtail is active in
the soil, so must be used with caution around desirable plants. However, it is not very harmful to trees and
shrubs. READ THE LABEL BEFORE BUYING AND APPLYING ANY PESTICIDE.
Since you said you are primarily using a backpack sprayer, it is possible for you to spray individual
plants carefully, thereby limiting the amount of spray getting onto the soil or other plants. Another
possibility is to use a 'wiper" applicator, with which you wipe the herbicide on the plants. This greatly
reduces drift to desirable plants,
An alternative chemical that I mentioned is Arsenal. However, after reviewing the label I noticed that it
also kills grasses. This is not a good idea if you have grasses that will compete with the knapweed. Plant
competition is a good way to prevent reinvasion of knapweed, so you don't want to kill desirable grasses.
After spraying the knapweed, it is very important to reseed with competitive grasses. I have enclosed
information on reseeding mixes based on recommendations from the Natural Resource Conservation Service.
Note that if you broadcast the seed, you will need to use higher rates. Drilling is more effective, but I
understand that you may not be able to do this in the pit areas.
Please do not hesitate to contact me if you need further information or would like me to visit the gravel
pit to assess the situation. I also would like to hear how your control program is progressing.
Your cooperation in controlling noxious weeds in Mesa County is greatly appreciated.
Sincerely,
Judith M. Sirota
Mesa County Horticulture Pest & Weed Inspector
cc: Steve Shuey, Colorado Div. of Minerals and Geology
enc: reseeding -desert, riparian
Nursery Stock Inspection - Horticultural Pest Control - Noxious Weed Management