FAA/Mount Lewis Road

CD established the Noxious Weed Control Demonstration Project with several plots and different noxious weed species - Mount Lewis/FAA Road.

FAA/Mount Lewis Road

The purpose of this demonstration was to test the effectiveness of Plateau herbicide on Russian Knapweed. Plateau is selective against herbacious broadleaved species, thus it would have application where Knapweed has invaded into areas native with grasses and shrubs.

9/15/99
Russian Knapweed. Sprayed with Plateau herbicide 8/28/99. No apparent affect

4/21/00-Same view. Roadbed had been bladed. Dead plants removed. Dead plant visable on shoulder. Knapweed sprouts were evident at the time of this picture in bladed area and under the standing skeletons on the shoulder.

5/16/01-Same location. Regrowth in roadbed. Sprayed with Tordon June 2001. Regrowth on shoulder and skeletons. Sprayed with final treatment of Plateau August 2001.

1. Treatment.

Plauteau herbicide was applied to all disturbed areas along this road where Russian Knapweed had invaded. Treatment was before frost in late August or early September of 1999, 2000, and 2001. Blading of the road surface during June or July as part of routine maintenance each year kept plant tops cut off without affecting control of the Knapweed growing in the road. Tordon 22K was applied to the road surface at the maximum recommended rate as an expedient control in June, 2000 and 2001.

2. Results.

Tordon completely killed out the Russian Knapweed growing in the road surface in two applications. Plateau was nearly 100% effective after three applications. Two applications of Plateau gave about 90% kill on Knapweed. The grasses were unhurt and most of the shrubs sprayed in the treated areas survived.

3. Conclusion.

Plateau herbicide is highly effective against Russian Knapweed with repeated applications in late summer to early fall (before 1st frost). Its selectivity is especially useful in areas where Russian Knapweed has invaded among non-target shrubs and grasses. Follow-up treatments are required for complete control.

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