Have you seen this plant?

whitetop: Area landowners are encouraged to report infestations of whitetop to the Tri-County Cooperative Weed Management Area office so that new weed-infested locations can be surveyed, treated and recorded for future follow-up treatments.

Tri-County Cooperative Weed Management Area  awarded $17,490 to help Union County residents and landowners combat whitetop 

That prolific white-flowered plant that appears in areas throughout Union County during the spring each year is not a desirable ground cover. 

This plant is commonly known as whitetop or hoary cress, and is listed both by the State of Oregon and Union County as an invasive noxious weed. Union County Weed Control and other agencies have been battling the spread of whitetop populations since the early 1970s.

Over the years people have attempted many mechanical control methods such as hand pulling, mowing and cultivation, to no avail.

Mechanical control of this plant is not a viable option because whitetop is a deep-rooted perennial that spreads not only by seed, but also by underground runners called rhizomes.

The vast majority of this plant remains underneath the soil surface year round. Mechanical control typically removes the above ground portion but invigorates the root system to spread and form new plants all around.

If a person tills the ground hoping to destroy whitetop, he or she is actually compounding the problem exponentially as each small root fragment will sprout and form a new plant.

Chemical control has been attempted for many years — decades even — by numerous people throughout the area. The problem in the past has been that the herbicides used were not very effective against whitetop.

Glyphosate products (i.e. Roundup) or some combination of 2,4-D and Dicamba (Weedmaster) have been used extensively with limited results. Often times people become  frustrated and just give up with the assumption that they are powerless against this tenacious invader.

Recent advances in the herbicide industry have produced highly effective chemicals for the treatment of whitetop. Herbicides in the sulfonylurea family, which includes Escort and Telar, have the ability to translocate throughout the entire plant and effectively kill the rooting system.

Advantages of these newly derived herbicides are the increased mortality to site-specific weeds such as whitetop and a decrease in mortality to non-target plants, including most perennial grasses.

Tri-County Cooperative Weed Management Area has been awarded $17,490 in grant money to help Union County residents and landowners combat whitetop. With the help of this grant money and additional funding entities, Tri-County hopes to continue reducing the spread of whitetop infestations and minimize the spread into Union County.

To control whitetop, Tri-County has divided the rural areas of the county into first, second and third priorities. This allows for control of isolated and outlying populations before moving to more heavily infested areas in the southern most part of the county.

To date, Union County has withstood the spread of heavy whitetop infestations within its borders. With the help of grant money and additional funding provided by coordinating agencies and organizations, Tri-County hopes to reduce whitetop populations and to minimize whitetop spread within Union County.

Tri-County encourages landowners to report infestations to its office so that new locations can be surveyed, treated and recorded for future follow-up treatments. Contact Tara Bohnsack at Tri-County Cooperative Weed Management Area, 541-523-2740 with any questions or whitetop sightings.

Tara Bohnsack is weed specialist for the Tri-County Cooperative Weed Management Area.