Turf Update – 18 May 2007

Spring conditions albeit on the cool side have been good for cool season turf growth. However, the cool weather has delayed green-up of warm season zoysiagrass turfs. Timely and apple rains have limited the need for irrigation, if any. The need for spring fertilization should be minimal if adequate fertilization was done during the fall of 2006.

We are entering a time of the spring when any fertilization should be done at low to moderate rates of nitrogen with the objective to maintain turf vigor at a low to medium level. Generally, aggressive fertilization at this time of year can result in extremely rapid shoot growth that could compromise plant health once the weather becomes warmer and the soil becomes drier.

Spring is a critical time to mow at the correct frequency. The general rule of thumb is to remove no more than ⅓ the length of the leaf blade in a single mowing. For example, you should mow the turf when it reaches 3 inches if you mow at 2 inches (1 inch from 3 inch high leaves or 1/3). Cutting more than 1/3 of the leaves stresses the grass plants and ultimately makes the turf more susceptible to weed invasion and damage from environmental stress and pests. Turf mowed at 2 to 3 inches should be cut at least once a week when the grass is growing rapidly; cutting twice a week will improve the beneficial effects of mulching mowers and enhance the health of the turf.

Many grasses have entered the flowering portion of the yearly growth cycle so seed stalks can be visible on many turfs imparting a stemmy appearance. This could continue for several more weeks in some cases. Low rate N fertilization can be used to restore the leafiness of the turf if the stemminess becomes objectionable; however, avoid over-fertilization and apply no more than ½ pound of nitrogen per 1000 square feet within a 2 two to four week period.

Any repair of turf areas with seed or sod should be complete; if not, this work should be done as soon as possible. The approaching warm weather increases the probability that areas repaired after mid-May will struggle and possibly fail. Seeding and sod transplanting after mid-May are very likely to require routine irrigation to be successful. Keep this in mind if you considering late spring repairs of turf.

Those applying compost or organic fertilizers should apply this material in the spring before the warm weather arrives. Generally, a large volume of these materials has to be applied to be effective and it can take time for the material to filter through the turf canopy to the underlying soil. Smothering damage is more likely to occur with these materials when the weather is warm or hot. Brushing or drag-matting the turf after the application can avoid this smothering damage. Also soil test before you apply more compost or organic fertilizer; these materials are not only high in organic matter but also phosphorus and many soils in New Jersey already have adequate amounts of phosphorus. Soil testing will be able to determine whether your soil needs additional phosphorus or organic matter.