Stevens County Noxious Weed Control Board
This web site will help you identify & control noxious weed with information and photographs to aid you.

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Hoary cress & Hairy whitetop
Cardaria draba (L) Desv & Cardaria pubescens (C.A. Mey.)
Mustard Family

Hoary cress & Hairy whitetop are closely related species of mustards. All identifying traits apply to both, unless stated otherwise.

Key identifying traits

  • Flowers are small & white and form dense flat-topped clusters from May to early June
  • Alternate, oblong to arrow-headed leaves clasp the stem; they range from -3" long, have a bluish-green color and a waxy feel to them
  • Fruit is heart-shaped (hoary c.) or globe-shaped (hairy w.) and tipped with a "beak"
  • Seeds are oval and reddish-brown and come two per pod (hoary c.) or four per pod (hairy w.)

Biology and ecology

  • Long-lived perennials, reproducing by seed and underground horizontal roots (rhizomes)
  • Introduced from central Europe & western Asia
  • Will form a large dense spreading colonies if not controlled
  • Thrive under a wide variety of soil conditions
  • Bloom and set seed early in the growing season
  • Problem in ditches, crops and pasture, once established it is very difficult to eradicate

Control

Prevention Learn to identify plants; know your property; target small infestations aggressively

Biological No known biological agents yet

Cultural Good vegetative cover helps but does not prevent establishment or spread

Mechanical Cutting/tilling will not achieve control due to the underground root system

Chemical Several effective at label rates but may require repeat treatments to kill root systems; best before bloom or in the fall; refer to the PNW Weed Management Handbook for specific chemical recommendations


rosettes


pods of hairy whitetop


pods of hoary cress

 


infestation


Where found
Found in scattered locations throughout Stevens County, especially in abandoned crop land.

MSdoc     pdf

 

weedboard@co.stevens.wa.us
Last Edit: January 08, 2014
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