The Russian Dandelion (Taraxacum kok-saghyz Rodin) is a native plant of Uzbekistan and Kazakhstan and was first brought to the United States in 1942 to be tested as an alternative source of rubber production as part of the Emergency Rubber Project. The project conducted research on alternative sources of rubber in the wake of the Japanese takeover of southeast Asian rubber supply. The dandelion grows rubber-bearing latex in its root structure that can be harvested and processed into rubber products.
Field experiments administered by the Bureau of Plant Industry in 1942 provided the first research on the dandelion’s production capabilities in the United States. The plant grows well in a wide range of soils under varying climate conditions, but does not grow well in overly hot temperatures. Experiments found the dandelion responds well to growing conditions in the northern United States – specifically north of an imaginary border spanning southern New York to southern Oregon. The plant’s ideal growing conditions include well-drained areas that receive annual precipitation of 20 inches or more. Loam to silty clay loam soils and soils with a rich organic composition or mineral soils with high organic content provide the best soil conditions for the plant. The dandelion’s livelihood is reliant on ample insect populations to spur maximum pollination. Researchers recommend a seedbed that is level, deeply plowed, smooth, very firm, and free of clods. Dandelion seeds planted in fields previously used to grow sugar beets or potatoes, showed more successful growth than fields previously used for grain, corn, or pasture. Roots can be harvested in the fall after a single season of growth or in the following spring during the second year of life. Harvesters must be careful to minimize breakage to the root in order to reduce the loss of latex that can escape through root damage. Wild germplasm was used during the Emergency Rubber Program experiments, with yields of most plants producing 2-3% rubber in the root dry weight. It is thought that with further seed refinement, rubber yields can increase.
After a labor intensive harvest, roots are processed by leaching them in hot water. The hot water treatment serves two purposes. First it removes the soluble carbohydrates, mostly inulin, that can also be used for ethanol production. Second, leaching softens the tissue and coagulates the latex into fine filament. Pebble milling then loosens plant tissues and rolls together the rubber filaments which are then separated from root solids by a vibrating screen and flotation. It is thought the remaining plant matter can be used for biogas production.
By 1945, Russian Dandelion grew into 40 states with land grant universities doing much of the research. Test plots were closed the same year, however, and all germplasm was eradicated from U.S. domestic rubber production programs.
Whaley, W.G.; and J.S. Bowen. “Russian Dandelion: An Emergency Source of Natural Rubber.” United States Department of Agriculture, Miscellaneous Publication No. 618. June 1947.
Van Beilen, J.B. and Y. Poirier. “Guayule and Russian Dandelion as Alternative Sources of Natural Rubber.” Critical Reviews in Biotechnology, 27:217-231,2007.
Links checked August 2018.