Alias: Hoary cress, pepperwort
Stems: 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, four sepals and petals,
petals about 1/4-inch long and white. Flowering period is in early
- Fruits: Inflated, 1/8-inch long, heart-shaped at base
and topped by a persistent style. Prominently veined at maturity,
bearing two (or four) reddish-brown, small, flat seeds.
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 overgrazed.
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).
- 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.
- 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.
Report all sightings to your local