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This article in AJ

  1. Vol. 92 No. 1, p. 167-172
    Received: Feb 19, 1999

    * Corresponding author(s): schillw@wsu.edu
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Soil Water Use and Growth of Russian Thistle after Wheat Harvest

  1. William F. Schillinger *a and
  2. Frank L. Younga
  1.  aDep. of Crop and Soil Sciences and USDA-ARS, Washington State Univ., 201 Johnson Hall, Pullman, WA 99164-6420 USA


Russian thistle (Salsola iberica Sennen and Pau) is a major broadleaf weed in dryland crops (<300 mm annual precipitation) in the Pacific Northwest of the USA. Russian thistle frequently infests wheat (Triticum aestivum L.) and other spring-sown crops, especially during drought. Quantitative information on water use, biomass accumulation, and seed production of Russian thistle after wheat harvest is lacking. In a 2-yr field study at Lind, Washington, Russian thistle plants were allowed to grow yearly in spring wheat in a grid pattern without competition from other weeds. Individual Russian thistle plants used 70 L of soil water while growing with the crop. From wheat harvest in early August until killing frost in late October, each Russian thistle used an additional 100 L of soil water. Water use occurred within a 1.5-m radius of the Russian thistle. Spring wheat competed with Russian thistle for water at shallow soil depths; most water use by Russian thistle was from deeper than 1.0 m. Russian thistle dry weight increased from 170 to 1280 g per plant between grain harvest and killing frost. Russian thistle seeds were either not produced or germinable until mid-September. By late October, individual plants had produced 67000 and 25000 seeds in 1996 and 1997, respectively. In low crop residue situations, rapid post-harvest growth by Russian thistle (before seed production) provides valuable surface cover for erosion control, but with the prospect that soil water may be reduced for the subsequent crop.

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Copyright © 2000. American Society of AgronomySoil Science Society of America