News and Opinion from Sisters, Oregon
News and Opinion from Sisters, Oregon
Central Oregon's Diffuse and Spotted Knapweed infestations are more easily controlled now as the rosettes begin to emerge on the local landscape. Spraying with herbicides or removing the plant before flower and seed stalks appear is the most effective means of controlling one of the area's most troublesome weeds.
Knapweed spreads by seeds, and in the case of the Russian type, by rootstocks as well. It is considered detrimental because it spreads rapidly, forming dense stands on range lands which choke out more desirable forage species.
Where the plant has been left unchecked, the Diffuse variety has overrun roadside ditches, prairies and dry range lands in the Sisters area, while Spotted Knapweed makes a stronger appearance around Bend. A couple of other varieties, Meadow and Russian Knapweed have also put in a less than welcomed appearance in Oregon lately, but have not taken a foothold here.
According to Joe Wichman of Prineville's Bureau of Land Management, this plant is not one agriculture officials want transported to new regions as an ornamental planting, or as decorative "everlasting" (dried flower) material.
Dave Langland in the Redmond Oregon Department of Agriculture office said the BLM, the U.S. Forest Service and ODA work together pursuing a program to check the noxious weed.
Control measures include chemical application, bio-control, and manual plant removal. Methods vary, depending upon the sensitivity of each locale. Mr. Langland also said that bio-control methods have been in place in the Plainview-west-to-Sisters area for some time, with an expansion of bio-control methods planned for the future.
Chemical applications include heavy-duty herbicides; bio-control releases insects on weed infestations to weaken plants, thereby evening the odds for other vegetation. Manual plant removal means pulling up plants by hand to stop its spread by seeds.
Eurasian in origin, knapweed is thought to have come into the U.S. and Canada as a contaminant of alfalfa and clover seeds in the late 1800's.
Identification of knapweed is not always easy, but it can generally be recognized by the following characteristics:
The base of the prickly, thistle-like plant is a leafy live green rosette from which tall, dry-looking stalks grow. The woody stems have grayish-green leaves and numerous, narrow, heads with few flowers. Flowers, when they appear, may be white, rose or purple, or, rarely, cream colored.
Fruits on the Diffuse plants are brown or grayish with longitudinal stripes. On Spotted Knapweed, fruits are distinguished by a tuft of short bristles at the tip of the fruit. Flowering times vary from June through October, depending on the type.
Contact Dave Langland and Glen Miller, at Oregon Department of Agriculture in Redmond at 541-548-2241 for help in planning a course of removal or call the Oregon State University Extension Service at 541-385-1410.
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