Turf - Winter Kill

Turf winter kill can be a problem, especially in seasons with fluctuating temperatures or with winter droughts. The following is an article on the subject.

Winter kill is a general term used to describe the loss of turfgrass plants during winter months. Loss of turfgrass plants during winter months can be caused by factors such as: low temperature kill (freeze damage of warm season grasses such as zoysia or bermudagrass), desiccation (drying out of plant material), heaving (freeze thaw cycle forcing roots out of the ground), disease activity (such as cool season brown patch) and insect damage such as fall feeding by grubs.

In most years, heaving and desiccation is the number one reason for winter loss of turfgrass in home lawns, commercial properties, sports fields and golf courses. With the extensive drought conditions throughout 2007, and the freeze thaw cycles we have had in the winter months, loss of turfgrass from desiccation is potentially going to be a continued problem throughout the remainder of the winter. This is especially the case in new seedings (seeded in the fall) and thinner turf stands.

After a winter of periods of alternating mild and cold temperatures; snow, ice, and rain; and frequent day/night thaw freeze cycles, turf areas may be showing symptoms ranging from dead or dying plants to yellow, stunted plants. Winters characterized by a number of freeze-thaw cycles can lead to heaving that can force the grass crown out of the soil where desiccating winds can kill small susceptible seedlings and even larger established plants. The crown region of grass is a growing point region that produces new leaf buds; tiller buds; and, in the spring, new adventitious roots that form the spring root system. Until the new root system develops enough for the new roots to become active, little nutrition and possibly too little water is taken up by the plant. Injured plants may not show stress until the temperatures warm and they begin to grow. By about mid March, you will begin to see these plants turn color and report that the grass is 'going backwards'. It is during the time when the plants begin to re-grow and new roots become functional that turf will look the worst.

Cool season brown patch or yellow patch may also appear on on home lawns, greens and tees. Unlike brown patch, which occurs in the summer, yellow patch (Rhizoctonia cerealis) thrives during cool, wet weather between October and May. Patches are chlorotic (yellow) and typically range from several inches to three feet in diameter. Patch centers are frequently green, resulting in a “frog-eye” or yellowish ring effect. There are a number of fungicides that are effective on cool season brown patch. Even without the use of fungicides, symptoms generally disappear when warm weather returns.

Article adapted from a number of extension sources including writings from Bob Mulrooney, Extension Plant Pathologist, UD and Richard Taylor, UD Extension Agronomist.