Western whorled milkweed (Asclepias subverticillata) is currently blooming in Delta County. It is most common in the North Fork and Surface Creek areas.
This plant is very toxic. If cut and dried with hay, it can be fatal to cows and horses. White flowers and milky latex sap identify this perennial species. It reproduces by seeds and horizontal underground roots. This herbaceous perennial is common along roadsides, ditchbanks, in pastures and hay fields.
Colonies spread by seeds or underground rootstalks that are not disturbed during tillage practices. The milky latex sap that exudes when plants are cut or grazed is not palatable to livestock. Control by pulling is only short term. The plant will return the next season.
Effective herbicides are Tordon, dicamba (Banvel, Oracle, Clarity) with any 24d amine product. Mix 1 oz. of each product into 1 gallon of water with a surfactant. Glyphosphate products work but are non-selective and will kill surrounding vegetation. The most convenient product for small patches can be found in hardware stores. It is called WEEDFREEZONE. Mix at 2 oz./gallon of water for small sprayer application.
More information about whorled milkweed and other weeds in Delta County, including photos, can be found at www.
deltacounty.com. Press the Weed Program tab under Services.