Tuesday, September 18, 2012

Winter Injury

What does Winter Injury mean?

The term "winter injury" has been traditionally associated with a variety of forms which are related primarily to meteorological events, although some are more directly caused by inherent turfgrass weakness, man-made events, and disease and insect pests.

Winter Injury in turfgrass

Cold or  freezing - Soil temperatures below tolerance temperature levels which will cause winter kill.                                                   

Crown hydration - Excess water, ice covers, and poor drainage contributing to cold temperature injury and winter kill.

Desiccation injury - Wind exposure, or soil drought, which create "wind burn" injury.

Discolouration of leaves - Grass types that have poor low temperature colour retention during the winter months.

Freeze-thaw injury - Alternating temperatures, or frequent that's, that contribute to cold temperature injury.

Fungal diseases - Snow moulds, such as Typhula blight and Fusarium patch.

Late Spring freezing injury - Fatally cold temperatures after Spring snow melt, at a time when grass is most subject to winter kill.

Mechanical damage - Frozen turf damaged by traffic, such as vehicles and people.

Poor Winter hardiness - Cold temperatures will cause winter kill first on more susceptible grass species such as the ryegrass and tall fescue.

Road salt injury - Salt spray drifting from adjoining road or highway treated with de-icing products will cause winter kill to nearby grass.

Rodent damage - Mice will tunnel between snow and ground, and moles, will dig up turf looking for food in the Spring.

Seeding injury - young grass not yet mature for winter hardiness will be subject to cold temperature injury and winter kill.

Submergence or flooding injury - Excess water, flooding, poor drainage, and low areas contributing to cold temperature injury and winter kill.

Urine damage - Domestic dogs, as well as various wildlife such as deer and elk, will deposit fatal amounts of material on turf.

Winter kill - Winter kill is the result of injury caused by cold temperatures, desiccation, crown hydration and other factors. Cold temperature injury is the major factor.

The most serious form of Winter Injury - Winter Kill

Winter Kill occurs when the crown tissues are fatally injured, resulting in the death of turf. Winter Kill is the most damaging result of winter injury because the crown - the heart of the plant is irreversibly injured. Once the crown has been killed, the adjoining plant parts, such as leaves and roots, will also die.

To the unaided eye, winter kill may appear as blackening of the crown. In more advances stages, the adjoining leaves and roots will perish as well, and also appear black or brown.

A low level of winter kill may occur when the crown tissues are discoloured with a brown or tan colour, however, the inside or the crown may still remain white. It can be observed that small crown tissues will be killed more easily than large ones.

Winter kill is the result of injury caused by cold temperatures, desiccation, fungal disease and crown hydration. Overall, cold temperature is the major factor affecting the winter survival of all turgrasses in Canada.

Poor Drainage and Winter Kill

Poor drainage is one of the most critical causes of turfgrass winter kill. This fatal injury is basically caused by excess standing water or flooding , whereby turf succumbs more easily to cold temperature.

Posted by Perfect Landscaping at 12:00 PM

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