February 5, 1999 | By: Mark Eclov

Short-sleeve shirt temperatures in January and February have a lot of Ohio valley residents worrying about how the warm weather may affect their landscape plants.

"If homeowners have done a good job of mulching their plants and we get back to normal temperatures within a short time, mulches should prevent soil from warming too rapidly and moderate plant damage," said Bill Fountain, Extension Horticulture Specialist in the University of Kentucky College of Agriculture.

Fountain added that soil temperature control is just one of the many benefits provided by mulching with the right materials. On the other hand, too much mulch, or mulch put in the wrong spot, can invite rodent damage to shrubs, fruit trees and many prized specimen plants used in the landscape -- damage that looks like freeze-related plant stress or disease.

"Low ground covers provide a perfect place for field mice and other rodents to nest through the cold winter months. Another ideal nesting site is in mulch that has been piled up around tree trunks," warned Fountain.

"The warm weather like we have experienced wakes up rodents from a long winter's nap and just like humans, they begin search for their breakfast," said Fountain. "Often the closest meal is a prized shrub or ornamental plant."

While it is difficult to keep rodents from nesting beneath low-lying shrubs, homeowners can reduce ideal accommodations for these pests by never applying mulch more than three to four inches deep around trees and also by pulling the mulch a few inches away from tree trunks prior to the onset of winter, or when warm weather threatens to wake the rodents from their winter rest.

The irony to this mulch and mouse story is that a lot of rodent damage will probably be blamed on stress, or diseases related to the warm weather.

"Unless you specifically look at the stems at ground level, you will not immediately see the damage they have caused," said Fountain.

Homeowners typically bring in a minute clipping from the tip of a dead branch to the county Extension office. This prevents the UK diagnostic labs from being able to see the true cause of the branch death which may be girdling caused by mice chewing on branches.

When rodents eat, their teeth generally leave two parallel U-shaped grooves in the wood stem. It may require a hand lens to see these grooves. "An accurate diagnosis requires a plant sample large enough to show the cause of the problem," said Fountain.

UK Cooperative Extension Service County agents have access to fact sheets on the benefits and proper use of mulches, plus recommendations for controlling rodents that may be identified as the source of plant damage.

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Contact: 

Writer: Mark Eclov
(606) 258-7223

Source: William Fountain
(606) 257-3320