Effects of clipping and sheep grazing on dyers woad

- Authors: N. E. West, and K. O. Farah
  
  Date: 1989
  
  Journal: Journal of Range Management
  
  Volume: 42
  
  Number: 1
  
  Pages: 5-10
  
  Summary of Methods: This two year study in the Wellsville Mountains, Box Elder County, Utah compared the effects of mechanical clipping and grazing by sheep on dyers woad (Isatis tinctoria) characteristics. Grazing intensity varied from light (less than 40% grazed) to moderate (60% clipped) and severe (90% clipped). Plants were subject of varying clipping frequencies (1, 2, 3, and four times) from April to May. Vegetation measurements were taken before and after grazing and clipping treatments.
  
  Article Summary / Main Points: At least three clippings at a high intensity percentage (60-90%) were required to increase mortality rates and affect flowering ability of dyers woad. Sheep utilization of the weed was less than 40% at the beginning of the study, and sheep stopped grazing dyers woad about May 15 and switched forages completely. Thus, sheep grazing did not affect plant mortality or seed production of dyers woad in this study. Stocking rates required to achieve this level of utilization would potentially lead to further range deterioration.
  
  Vegetation Types: Cactus Succulent Desert California Grasslands (including all annual grasslands) Chaparral Desert Grasslands Desert Shrublands Grazed Forest Intermountain Grasslands (includes Palouse Prairie and Canyon Grasslands) Mountain Shrublands Oak Woodlands Pinyon-Juniper Woodlands (includes juniper woodlands) Ponderosa Pine Woodlands Sagebrush Steppe Salt Desert Shrublands
  
  MLRA Ecoregions: 28A Great Salt Lake Area 47 Wasatch and Uinta Mountains
  
  Agrovoc Control Words: Weeds Rangelands Grazing
  Article Review Type: Refereed
  
  Article Type: Experimental Research
  
  Keywords: isatis tinctoria, biological control, utilization by sheep, weed mortality, seed production, forage selection, utilization pressure
  
  Annotation: Use of sheep grazing to control dyers woad is not a viable option at this time. The results from this study are highly applicable across the west as dyers woad has invaded many areas across the western United States.

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