David M. Kopec, Extension Turfgrass Specialist
Early November means mowing and fertilizing your overseed lawn for the first time in Phoenix and Yuma, considering applying a snow mold fungicide in Flagstaff, and applying a late fall fertilization on Kentucky bluegrass, fescue and ryegrass lawns in Kingman, Payson, Prescott, Show Low, Sierra Vista and Winslow.
In the low desert valleys, the overseeded bermudagrass (perennial ryegrass, annual ryegrass, or intermediate ryegrass) will respond well to necessary fertilization in November. This should be the last time to apply a nitrogen fertilizer which is high in ammonium content. After November, use nitrate forms (see below). In November, applications of ammonium phosphate (16-20-0) provides both -N- and -P- to young plants which respond to surface applications of phosphorous, even on mineral soils. Apply up to one-half or three-fourths lb. of -N- in November. Balanced or complete fertilizers contain N-P-K. Select a fertilizer which has N-P-K in relative ratios of 3-1-2, 4-1-2, 2-1-2 or similar for the November applications. The added "K" will help stimulate winter hardiness. Many commercial fertilizers are available to do this. Examples include 21-7-14, 16-5-8, 10-6-4, etc.
It is important to mow on a regular schedule within the proper mowing height tolerance range for the overseeded grass. Annual ryegrass and intermediate ryegrass can be mowed at 1.5-3.0 inches, as the base mowing height. These are best mowed with a sharp rotary mower. Perennial ryegrasses can be mowed at 1.0-2.5 inches on home lawns. They can be mowed lower, but MORE OFTEN, with a sharp reel-type mower.
Once you decide on the mowing height, you need to be able to mow it again when the grass gets 33% taller than the base height. The young grass will suffer tremendously if you break this rule!
In Kingman, Payson, Prescott, Show Low, Sierra Vista and Winslow it's now time to deploy the late fall fertilization(this would be done October 30 in Flagstaff). At this time the application of nitrogen (in either the ammoniacal or nitrate form) will benefit the cool season grasses. The slow uptake of -N- allows the grass to couple with the fall carbohydrates to make important plant parts like new roots (and rhizomes for KBG) which will elongate when the springtime comes around. Apply 1.0 to 1.5 lbs. of -N-/1000 ft2 at this time, followed by 3/8 inch of irrigation or rainfall.
Up in Flagstaff, consider applying a preventative fungicide for snow
mold diseases. Snow molds can completely kill the turf during the winter,
whether there is snow cover or not. Snow mold is worse under conditions
of freezing and thawing cycles, accompanied by winter rains. Once the lawn
has completely stopped growing, the lawn can be mowed short (5/8"-3/4").
This actually prevents water loss from the leaves, thus avoiding winter
desiccation up in Flagstaff and other true high elevation areas.
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.