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  Weed Identification

Whitetop (Hoary Cress)


  • Whitetop | Source: National Agricultural Library, Agricultural Research Service, U. S. Department of AgricultureStems: Up to 3 feet high.
  • Leaves: Grayish-green, up to 4 inches long, shaped like arrowheads. Nearly entire to finely toothed and bearing soft fine hairs. Lower leaves stalked, upper reduced and sessile.
  • Flowers: Numerous and small, 4 sepals and petals, petals about 1/4-inch long and white. Flowering period is in early May.
  • Fruits: Numerous and small, 4 sepals and petals, petals about 1/4-inch long and white. Flowering period is in early May.

 

Whitetop can establish itself in a variety of soil types and environmental conditions: dry pastures, hay meadows and roadsides, cultivated crops. A single plant can send out 400 shoots in a year. Roots develop to depth of several feet, making control difficult. It spreads by seed and root.

Control: Integrated pest management is the best method of controlling this weed.

  • Biological: Dense stands of perennial grasses will out-compete whitetop. Pasture grasses will slow spread if not over grazed. Growing small grains in infested fields will suppress whitetop once a canopy is formed. No insects or parasites are available in the United States (as of Nov. 1991).
  • Mechanical: Cultivating fallow ground no more than 10 days after weed emergence will eventually eliminate the weed. Close mowing will also reduce seed production but will not eliminate.
  • Chemical: Most easily controlled with foliar herbicides applied during rosette stage. Depends on where infestation is located, what kind of herbicide and application is allowed.
    • Source: USDA Forest Service

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