Issue: April 29, 2006

Dead lawn this spring

As the weather warmed, I began watering my lawn only to discover that much of it was dead. What happened? What can I do to restore my lawn?

This is a common problem throughout New Mexico. In response, Dr. Bernd Leinauer, NMSU Extension Turfgrass Specialist, has written the following:

This spring, I have seen more areas affected by winter damage or "winterkill" in lawns, athletic fields, and on golf courses across the state than in any of the previous springs. The extremely dry fall and relatively cold and dry winter has certainly taken its toll on the turfgrasses.

Winter damage or "winterkill" are general terms that describe turf loss during the winter. It can be caused by a combination of factors including diseases (snow mold), desiccation, low-temperature injury, hydration, and anoxia (lack of oxygen). Desiccation and low-temperature injury are the two main reasons for turf loss in New Mexico.

Desiccation or death by drying out occurs every year to varying degrees. It is caused by exposure of uncovered turf to wind, leading to loss of moisture from the plants and soil. Desiccation is most common when air temperature is above freezing and the ground temperature is below freezing. A good snow cover usually prevents desiccation, but this certainly did not happen this past winter. Low-temperature injury is caused by ice crystal formation inside plant cells at temperatures below freezing. The extent of the damage depends on the grass type, length of low-temperature periods, minimum temperature experienced by the grasses, and the age and health of the grass exposed to low temperatures. Kentucky bluegrass exhibits good low-temperature hardiness, while perennial ryegrass is very susceptible to low-temperature kill. Grasses become winter hardy in the fall by reducing leaf growth and storing carbohydrates. To help prevent low-temperature kill: (1) do not fertilize heavily in early fall but use a dormant fertilization (late fall fertilization) to encourage root growth, and (2) decrease irrigation to "dewater" the plants. Variation in soil type, landscape undulations, shading, grass type, and other features can explain why some lawns show large areas of damaged turf and others are hardly affected at all.

Recovering from winter injury takes time. In general, to assess if damage has occurred, take turf samples, move them inside and place them in a sunny area to see if the grass greens up. If there is no green up within 2 weeks, the turf is dead. If there is no recovery in cool season lawns outside by the time this article is published, it is fair to assume that the grass is dead. However, recovery can be delayed by salinity buildup in the soil. In areas where lower quality water or water with a total dissolved solid reading(TDS)of greater than 1500 ppm is used for irrigation, salt accumulation and salt stress from capillary rise can be especially severe in the winter and spring if there little or no snow fall. A soil test conducted in early spring should not only help in determining the nutrient status in the soil but also reveal any problems associated with salinity.

Reestablishing turfgrass in damaged areas can be accomplished by seed or sod. If the damaged areas are well defined, sodding may be feasible. Scrape off and remove the dead patch entirely and replace with the new sod. In areas where the damage is more scattered, rake the patches thoroughly to remove all dead plant debris and to create grooves in the soil. Sprinkle seed on the areas and rake again to ensure good seed soil contact. Fertilize and water your lawn to ensure a speedy recovery.

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Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!