Local government

Got whitetop on your property? Malheur weed inspector offers tips to control it

Spring is finally here, and with the wet cool weather we have been having, the whitetop is growing like crazy. It is making its appearance in a lot of places, requiring all landowners to do their part to combat this noxious weed.

Malheur County Weed Department is no longer doing the whitetop chemical giveaway that many residents have become accustomed to, but there is still plenty that you can do to control it.

First you need to understand that whitetop is a perennial plant that can come back year after year from its root system, and seeds that it produces. Because of its deep root system, pulling the plant will only create more, so chemical application is the best control method. If removing the plants mechanically (pulling/digging) you have to keep removing all new growth as it continues to emerge and is only successful in very small areas, or with continued tillage.

Secondly, proper chemical selection, application and timing are critical to the success of your efforts.

To truly kill the plant down to the roots, it needs to be sprayed when the plant is actively pulling nutrients down to the roots for storage. This happens at the “bud stage.” Spraying before this stage will kill the plant above ground, but you will most likely see it back in the same spot in the late fall or early spring. Spraying after seed set is the least effective application timing.

When buying expensive chemical, and spending precious time to spray unwanted weeds, one really needs to ensure that they are applying it correctly.  Not mixing chemical correctly is a major contribution to undesirable results.

Mixing too much chemical, or spraying it too heavy will burn down the top of the plant, and possibly damage surrounding desirable grasses, even causing lasting damage to the soil where applied. Spraying too lightly will only knock the plant back allowing it to continue to flower, and increase the chances of creating a chemical resistant plant!

To mix product properly you need to know how much liquid you are applying to a specific area in a specific time. There are multiple links for calibrating your sprayer depending on what style you have. https://wyoweeds.org is a good site. They also have good videos on YouTube for Boomless ATV and backpack calibration at TZiehlTCWP.

Lastly chemical selection. There are a lot of different chemicals to choose from, and what you can use will depend on where you are applying it. Read the label to make sure you can apply it where you need to. All labels will list areas where that product can be applied. However, the absence of a particular weed from the label does not prevent use of the herbicide on that weed. Always read and follow the label!

For more information, contact Malheur County weed inspector Amanda Zander at [email protected] or (541) 473-5102.