Kochia (Kochia
scoparia L.) Family: Family: Chenopodiaceae Description and VariationDescription and Variation: Kochia is an annual plant that reproduces from seeds. It has a deep taproot. The erect, much-branched stems are three to seven feet long, smooth below but usually hairy above. The alternate, simple leaves are pubescent to nearly glabrous, one to two inches long, lanceolate to linear with hairy margins, and without petioles. The small green flowers lack petals and are found in clusters in the axils of the upper leaves and in terminal spikes. The brown flattened seeds are about 1/16 inch long and grooved on each side. Economic ImportanceEconomic Importance: Detrimental - In the Great Plains, where kochia is widespread, it is considered a serious pest of late-maturing crops such as sorghum, soybeans, and sugarbeets. It is also a problem in the fallow portion of the cereal-fallow cropping systems. Kochia is an effective competitor for light, nutrients, and soil moisture, and can reduce crop yield. There is a high variation in the flowering time of populations of kochia. Early populations can become a problem in cool-seasoned cereal crops. Montana considers kochia the fourth most important weed affecting cereal production. Beneficial - Kochia may have value in reclamation of disturbed land and as livestock fodder. Geographical DistributionGeographical Distribution: Kochia is native to Eurasia. It is now naturalized across the northern half of the United States and is spreading westward. It occurs in Washington, Oregon, and Idaho and is increasing its distribution in those states. HabitatHabitat: Kochia is highly adaptable. It is very drought tolerant and can spread rapidly in these conditions. It will not flower and set seed if the mean temperature is less than 15.5 degrees C. Kochia has a wide tolerance of soil types and is even adapted to salty soils. It is found on pasture, rangeland, roadsides, ditch banks, wastelands, and cultivated fields. HistoryHistory: Native to southern and eastern Russia, kochia was introduced to North America from Europe. It was grown as an ornamental hedge around gardens, or used as a backdrop planting because of its dense, conical shape and attractive red color in the late fall. It has since escaped cultivation and spread westward. Growth and DevelopmentGrowth and Development: Like many other species of the Chenopodiaceae, it becomes a tumble weed when mature. An abscission zone develops at the base of the stem in autumn. When winds reach velocities of 25 miles per hour, the stem breaks and the plants tumble. Kochia overwinters as seeds. The seeds germinate very early in spring because of their frost tolerance. Kochia grows very rapidly through spring and summer and sends down a very long taproot (up to 16 feet). It flowers in late summer and sets seed. ReproductionReproduction: The species typically produces around 14,600 seeds per plant. Seeds are dispersed in the fall when the plant becomes a tumbleweed. The plant tumbles with the wind, dropping seeds as it is blown about. Laboratory studies report germination rates of 76 percent or better over a temperature range of 39-106 degrees F. Seeds buried in the soil have five percent viability after one year and zero percent after two years. Kochia reproduces by seed only. Population DynamicsPopulation Dynamics: Kochia is able to spread long distances very rapidly. Its ability to tolerate drought also enables it to spread quickly. It was considered a rare plant in North Dakota and Kansas in the late 1920's, but with the drought during the 1930's it became abundant. Response to HerbicidesResponse to Herbicides: Infestations of triazine resistant kochia has been found along railroad lines in eleven states. Research has shown that triazine resistant biotypes were more susceptible to 2,4-D ester than triazine susceptible biotypes. There are also biotypes resistant to 2,4-D or Banvel (dicamba). It is suggested that rotating herbicides would reduce the possibility of an increase in the proportion of plants tolerant to 2,4-D or Banvel. Response to Cultural MethodsResponse to Cultural Methods: Early tillage in the spring gives good control of the kochia seedlings. Mowing or slashing the plants before flowering is effective in reducing seed production. Biocontrol PotentialsBiocontrol Potentials: None known. ReferencesReferences: Reed. 1970. Selected Weeds of the United States. USDA. 1970. Selected Weeds of the United States. Agriculture Handbook. No. 366. USDA-ARS, Washington D.C. Holm, L., J.V. Pancho, J.P. Herberger, D.L. Plucknett. 1979. A Geographical Atlas of World Weeds. Mitich, L.W. 1981. The Intriguing World of Weeds, Part IX. Weeds Today. 12(2):26. Smith, L.J., S. Dewey, D. Thill and B. Gallihan. 1983. Kochia scoparia. Univ. of Idaho, Ag. Extension, Bulletin #722. Eberlein, C.V. and Z.Q. Fore. 1984. Kochia Biology. Weeds Today 15(3): 5-7. Forcella, F. 1985. Spread of Kochia in the North-Western United States. Weeds Today 16(4): 4-6. Hawkes, R.B., Whitson, T.D. and L.J. Dennis. 1985. A Guide to Selected Weeds of Oregon. Oregon Dept. of Agriculture Press, Salem. This page last updated 03/31/07 |
