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6/7/99
Salt grass prior to treatment. |
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9/15/99
Same location. Sprayed 8/28/99. Annual vegetation left of the salt grass was killed. Salt grass (center) shows initial signs of drying (desiccation) from the treatment. Note red pencil for scale. |
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5/11/01
Two years after treatment with Arsenal herbicide. Note residual control on the road shoulder and partial recovery of the site with seedlings of annual and perennial species in the sprayed areas. |
Arsenal was applied at six pints per acre along the road shoulders on 8/28/99. No other application was done. Target species included salt grass and gumweed.
The last survey of these sites was on 5/11/01. There was still evidence of control at each site. In some areas along both roads a demarcation was apparent where the spray ended off the roadside. Although some species were growing back in the treated areas, some individual plants were still sick, but not dead. Full effect of the herbicide was not evident until the growing season after treatment. In no case was there 100% kill of the target species.
For complete control of persistent species along roadsides, at least two applications of Arsenal on successive years are required. A second application in 2000 would have been helpful to learn whether this chemical will provide an acceptable amount of control without continued treatment; indications are that it will. This demonstration was inconclusive.