Sunday, March 16, 2008

Russian Thistle

What’s growing in the area: Globe willows are a brighter green. Apple trees were pruned in the main orchard this past week, the week before holy week sometime after the new moon. At least one field’s been tilled; many have been out cleaning dead leaves and weeds.
In my yard: Iris emerging; hyacinths up with buds visible. New growth on rockrose, snapdragon, coral beardtongue, bouncing Bess, golden spur columbine, pink evening primrose, Saint John’s wort, flax, hollyhocks, winecup, autumn joy sedum, tansy, Mount Atlas daisy, chrysanthemum, anthemis, hairy golden aster. Buds fattening on forsythia, spirea, cherry, and peach. Rose stems still green. Some grass blades up which could be cheat grass or Russian thistle; new growth in June grass clumps.
What’s blooming inside: Aptenia, zonal geranium, kalanchoë, bougainvilla
Animal sightings: Quail took off from area by the garage; small birds flittered near cholla.
Weather: Warm afternoons melted remaining snow, even though morning temperatures were still below freezing; high winds Friday; 11:50 hours of sunlight today.
Weekly update: High winds yesterday and the day before insured another good season for tumbleweeds.
Russian thistles produce their seed in late summer, but it isn’t ready to germinate until it finishes ripening in early spring. After last fall’s frosts slowed photosynthesis to reveal red betalains in formerly dark green stems, plants formed scar tissue near their bases with abscisic acid, which allowed this past week’s winds to break the half-inch woody stems, pick-up the dried spheres, and scatter shiny, dark seeds and small branches until the missiles hit fences or passing motorists.
Nature spent the past few weeks preparing friable surface soil when snow melt and rain couldn’t penetrate the freeze line and evaporated into the air. The wind nicely covered the seed with loose dirt it picked up crossing barren fields.
In 1893, Lyster Dewey traced this spiny Eurasian pest to a shipment of contaminated flax seed sent to Bon Homme County, South Dakota, in 1886. It took a few years to adapt to the new environment, then Russian thistle spread quickly on overgrazed range lands. McKibben found it in Lamy in 1894, the same year Southwestern Farm and Orchard warned readers it had been spotted in Santa Fe. Lamy was the main junction for the Atchison, Topeka and Santa Fe railroad. The weed was widespread in the state by 1915.
The weed, now called Salsola tragus, is harder to eradicate than it was introduce. Indeed, during the droughts of the depression the USDA promoted the plant for animal feed, since this member of the goosefoot family is high in protein and carbohydrates. Researchers found when it first sprouted and still resembled grass it was fair forage. It remained palatable while it bloomed and could be cut as hay. However, once the papery green bracts turned pink, the soft leaves withered, and were replaced by sets of three sharp, hard spines that protected it from grazing until the rains and snows of winter resoftened the stalks. During this phase they recommended ranchers could chop it to mix it with alfalfa for fodder.
It would be nice if you could simply set fire to an infested field of bushes ranging from 2" to 6' across, but the leafless branches enclose air pockets that make it hard to ignite. Most of my neighbors go out in fall or early spring to gather plants into huge piles they let settle for a few days. Then the towering smoke is mustard grey and smells from sodium carbonate.

Usually they yank the bushes and thereby drop a few seeds into the newly disturbed ground. I use brush cutters, then handle the 4' high balls by the stem stubs because the thorns irritate my hands. If the plants are still green, I let them dry a few days, then flatten them with a shovel or board to eliminate as much air as possible. They still suffocate when they burn.

One year I tried a herbicide. It took several applications and then the plants rotted, fouling the air with a different smell, before leaving carcasses that still had to be removed. Another year I tried a weed eater early in the season, only to discover the ribbed stalks sent out long branches along the ground, below the level of the machine’s nylon line.

Finally I let nature handle the mess it created. Even though the seedlings aggressively put down taproots before they start to grow, they can’t handle competition. When too many seeds sprout, each grows only a few inches high. Since it’s an annual, this meant if I let other, less noxious weeds grow, they eventually would squeeze it out.

All I do now is make sure flying bushes stay on the other side of my fences and let my neighbors keep the problem they perpetuate.

Notes:California Department of Food and Agriculture. "Russianthistle or Common Russianthistle," Encycloweedia website, edited by B.Ohlendorf.

Dewey, L. H. The Russian Thistle and Other Troublesome Weeds in the Wheat Region of Minnesota and North and South Dakota, 1893.

Forbes, Adam C. and Kelly W. Allred. "An Investigation of Salsola L. (Chenopodiaceae) in New Mexico," The New Mexico Botanist, 6 July 1999.

United States Department of Agriculture. Forrest Service, Range Plant Handbook, 1937, republished by Dover Publications, 1988.

Young, James A. and Raymond A. Evans. "Germination and Establishment of Salsola in Relation to Seedbed Environment. I. Temperature, Afterripening, and Moisture Relations of Salsola Seeds as Determined by Laboratory Studies," Agronomy Journal 64:214-218:1972.

Photograph: Russian Thistles clustered at a barbed wire fence, 14 March 2008.

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