Weed Control

The topic of weeds is a big one. Chances are if you’re reading this you’ve identified a plant that’s growing where you’d rather have something else growing. For you that makes it a weed and you probably don’t need to be convinced to control it. However, there are many reasons for controlling weeds or unwanted plants. Weeds cost farmers millions of dollars every year in forms of mechanical, chemical, or biological control. Some weeds are toxic to people or livestock. Some weeds like Knotweed or Reed Canary grass are both invasive and not native. They will completely take over a landscape, crowding out natural or desirable plants. Many of these weeds are listed on the Washington State Noxious Weed Control Board Noxious Weed List. By law, land owners are required to control noxious weeds. Contact the Snohomish County Weed Coordinator, Sonny Gorman (425) 388-7548, for help identifying and eliminating any of these weeds.

There are many sources on the Internet to help identify weeds. Weed identification is important in order to use the right methods of control and at the right time. Timing of herbicide application is important because weeds have to be growing in order to absorb the poison and weather conditions effect whether herbicides remain on their target or escape to streams and groundwater. By just Googling “Weed Identification” many weed galleries with good images of weeds will be provided. WSU’s Pacific Northwest (PNW) Weed Management Handbook , King County and the WA State Noxious Weed Board  have weed galleries. The Pierce Conservation District has a list of Toxic Weeds to Livestock. Always read the label and follow instructions on herbicide containers. Buy your herbicides from a vendor with licensed chemical personnel on staff that can advise you.

People are usually anxious to learn what kind of herbicide they can use to get rid of a weed. Herbicides have their place but in order to insure successful eradication or in most cases control of a weed, a bigger picture of management practices are needed. Using pastures as an example, if a livestock operation continually over grazes and allows animal access all of the time, herbicides will never improve the pasture. Weed prevention means creating as close an ideal environment and management of the grass as is practical. That means checking the soil fertility with a soil test and adding necessary nutrients in the right amount at the right time. In the Northwest it probably means adjusting the pH or acidity of the soil with lime based on recommendations from the soil test. It means maintaining adequate height (three inches) on grass by removing livestock from pastures until grass recovers. Removing animals when the ground is really wet prevents soil compaction that denudes the ground, inhibits desirable plant growth and creates space for weed propagation. It means mowing after grazing to prevent any weeds from out competing desirable plants in height and spreading seeds. It may mean spot removal of weeds either by digging, pulling or spot spraying. The more prevention taken, the greater the success and the less the expense of time and money to control weeds.