Mowing invasive species

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By Ethan Proud | PREVIEW Columnist

Of all of the methods to manage invasive species, mowing or weed whacking can be an excellent control on top of being time efficient. Mowing an acre of weeds is just as quick as spraying and can have similar results if timed correctly. Simply put, the best time to mow a plant is prior to it producing a bloom. The worst time to mow is once it has gone to seed.

That’s not to say that mowing is the only management technique you will need. Perennial species like Canada thistle, yellow toadflax, leafy spurge or whitetop will continue to grow after a single cutting. These plants have extensive root systems and will need multiple cuts per season to exhaust the root reserves. Biennial or annual species can be managed more easily because they have a simple root structure and are designed to survive only for a season or two.

Here’s where the trouble comes in with mowing: Plants are smart — believe it or not — and they will outsmart you if you are not careful. After a cutting or two, the plant will learn that it cannot grow to a height of 2 feet tall and bloom, so it will bloom at the height at which it was mowed. In order to avoid this, raise your mower deck to the tallest setting and lower it when you observe this phenomenon. If the plant persists and blooms lower than your mower is capable of cutting, take out the weed whacker and remove it at the ground level.

Mowing to prevent flower formation is the minimum action needed legally for B and C list noxious species. For A list species like myrtle spurge, complete removal of the plant is required, whether it be by herbicide or by hand pulling. The only reported A list species in the county is myrtle spurge, which is a popular xeriscape plant despite its noxious weed status. Hand pulling can be an effective measure, but gloves are recommended as the plant contains a caustic sap.

Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.