The Steamboat Pilot & Today

Steamboat Springs — A grass fungus appears to be gaining ground in Routt County.

A couple of cases of necrotic ring spot have been confirmed this summer, Routt County Extension Agent C.J. Mucklow said. Ring spot is the effect of a perennial fungus that appears as rings of light green or yellow patches in grass.

“We’ve probably had it here, but this is the first time we’ve had it diagnosed,” Mucklow said.

Necrotic ring spot is destructive to Kentucky bluegrass, red fescue and annual bluegrass, according to information from Colorado State University.

Fairy ring and snow mold funguses also are appearing in local lawns.

“The general management is all the same,” Mucklow said of the different funguses. “We want to aerate. Don’t keep it oversaturated, overfertilized.”

Kyle Downey, who owns Downey Erosion Control and Seeding, said necrotic ring spot never fully goes away. If a lawn has it now, the fungus will appear again next year.

“It’s all over town,” he said. “It’s taking town out right now.”

The fungus spreads through dirt and not grass clippings, Downey said. He said he thinks it is being spread through aeration. Mucklow said it is possible to spread funguses through that process, which typically involves removing soil plugs to improve air flow.

Although aeration is good for fighting funguses because it dries the lawn, aerating over a fungus-infected area can spread the fungus, Mucklow said. People who aerate over an infected patch should clean the aerating tool with bleach and water before moving on, he said.

Fungicides also can slow a fungus, Downey said. But chemicals recommended for fighting necrotic ring spot must be spread during springtime, Mucklow said.

“Fungicides are not usually sold here,” he said. “We usually have to order them. We don’t really recommend them.”

Some types of grass are resistant or immune to necrotic ring spot. Planting those instead of other grasses or seeding them over infected areas could improve lawn appearance, Downey said. Perennial ryegrass is immune, according to information from CSU.

Mucklow and Downey said people should be careful not to water or fertilize their lawns too much because funguses thrive in that damp, fertile environment.

“We recommend watering early morning and evening,” Mucklow said. “Night’s OK, too. The key is to really soak it and let it dry completely out, so we don’t water every day.”

The clay soil in Northwest Colorado doesn’t soak up water quickly, he said, so watering heavily at one time just leads to runoff. Mucklow recommended watering deeply for a short period of time.

“We maybe water 15 minutes in the morning and 15 minutes at night for three days in a row and then don’t water for five days,” he said. “We can’t just do 45 minutes at one sitting; it’ll just run off.”

— To reach Blythe Terrell, call 871-4234 or e-mail bterrell@steamboatpilot.com