(Poaceae), prickly Russian thistle
, pitseed goosefoot, Chenopodium berlandieri (Chenopodiaceae), buffalo gourd, Cucurbita foetidissima (Cucurbitaceae), Drummond's clematis, Clematis drummondii (Ranunculaceae), peppergrass, Lepidium sp.
is particularly troublesome in arid and semi-arid regions of the western United States.
Monitoring Russian Thistle
(Salsola iberica) Root Growth Using a Scanner-Based, Portable Mesorhizotron.
"In summer we typically see a lot of ragweed and Russian thistle
pollen," he says.
is a summer annual weed, first reported in the United States in South Dakota in 1877 (Dewey 1893).
They are quackgrass, Canada thistle, burdock, white or oxeye daisy, snapdragon or butter and eggs, cocklebur, perennial sow thistle, sour dock, yellow dock, wild mustard, wild parsnip, and Russian thistle
As Pyne explained in Fire in America, the cattle industry introduced new sources of fuel like the exotic Russian thistle
as well as the ubiquitous cow chips, which, "sailing like flaming frisbees before high winds," became "a major threat to isolated farms and towns." In the pre-bulldozer epoch, moreover, cowboys routinely fought grassfires with a "beef drag": a dead steer, split open and hauled down the fire-line with lariats.
Besides ragweed, which is considered to be the pollen most responsible for late summer and fall hayfever in North America, there are other weeds that can cause pollen allergy, including sagebrush, pigweed, tumbleweed, Russian thistle
, and cockleweed.
Ragweed is the major culprit, but others of importance are sagebrush, redroot pigweed, lamb's quarters, Russian thistle
(tumbleweed), and English plantain.
The most common seasonal antigen was Russian thistle
. All 10 patients diagnosed with seasonal AR were sensitive to this antigen.
Currently, EBCL's top weed priorities include yellow starthistle, Russian knapweed, saltcedar, Russian thistle
, leafy spurge, hoary cress, perennial pepper-weed, spotted knapweed, medusahead ryegrass, and rush skeleton weed.
Through this network, the Frederick lab recently acquired four good candidate pathogens--two on Russian thistle
, one on Russian knapweed, and another on common groundsel.