July 1999

- -Half Empty or Half Full- -
Summer Transition Strategies

David M. Kopec, Extension Turfgrass Specialist

By mid-July, if your transition hasn't run its full course, you may be a little antsy. It's halfway into "summer" as we know it, and you may "require" a near full transition by this point. If you don't, there are some things you can do to help things along.


Full sun fairways may still have appreciable ryegrass. Fertilize regularly with 3/8 lb. N/1000 ft2 from ammonium (34-0-0) nitrates once a week. Keep things irrigated normally. Avoid -K- in the fertilizer at this time as it might toughen the ryegrass (or contract the stress affect of -N- on cool season grass in hot weather). The high night temperatures and high humidity of the monsoon (if it ever happens again) will help push the ryegrass over the edge.

If you are treating your turf for purple nutsedge using IMAGE, this herbicide will get rid of the ryegrass quickly. If there is no bermuda underneath, then you will have bare ground till the bermuda comes back.

In shaded areas, you may have ryegrass until late August. You know where these areas are, as you often receive comments at the end of the season. In these areas, the bermudagrass weakens every year as the trees get bigger and provide more shade. To keep the rye alive as best as possible in these spots note the following.

If possible, raise the mowing height (roughs only).
Aerify with deep tines, or hydroject. Do not hollow core.
Treat with 0-0-50 at 1/4 lb. K/1000 ft2 per week and water in.
Spray iron only for green color.
Apply a routine application of preventive fungicide (rotate chemical families) for brown patch and phythium.


On greens, carefully check the condition of the bermudagrass. Pay specific attention to:

What percentage of the green is bermuda.
How much of the cool season grass is remaining.
What cool season grass is remaining (if rye and Poa trivialis was used).
How much bare turf is showing.

How much is bare turf.
If you have more than 5% or more bare ground on the green, you don't want to force out what's there because there isn't enough of what should be under it (bermuda).

Normal fertilization and irrigation should favor the bermuda without loss of overall turf. Stolons of bermuda growing into bare areas should not be verticut during this condition. Wait until the area(s) have 85% bermuda. Then verticut, topdress and fertilize. This will make the stolons "upright" which results in a better green.

What grass and how much remaining.
If you have 50% or more ryegrass, push with fertilizer and mowing. If you have only some ryegrass and mostly bermudagrass (75%) go ahead and verticut lightly in one direction.

If you have 30% or more Poa trivialis present, try grooming with 3-4 grooms/week. This will chop up the horizontal stolons. The green will lose some visual and putting quality for 2-3 weeks. Then fire up with nitrogen the first week in August. The PT will be overpowered by the bermudagrass.

If you have 30% or less of the ryegrass, go ahead and aerify and topdress followed by high -N- fertilizer applications. The rye will allow the bermudagrass to "snake in" between it.

What does the bermuda look like!
Tifdwarf and especially Tifgreen can have different "shades" on the greens and tees.

You often see areas of light and dark grass on the green. This is due to the light reflected off the leaves. Upright leaves occur in a dense canopy because the stolons grow more erect because of natural competition. This is a good condition for the green to be in! Lateral leaves (from leggy stolons) form another color in the green. These leaves are laying more horizontal along the ground. This is because the stolons are horizontal -- growing in "fill in" mode. The stolons must be anchored at several points along the stem with roots if they are to take a "one way" verticutting and topdressing. If not, you will most likely lose all the potential plants "downstream" from the verticut slice.

Fertilize regularly with water soluble -N- to make the stolons numerous and "crowded" before verticutting the horizontal stolons. Follow with -N- and topdressing and you will get the desirable upright stolons -- afterwards!

What if my greens are 90% or more bermuda.
Perform normal summer maintenance. Verticut deep, one direction at a vibratory shaking depth (Tifgreen only). This cuts all rhizomes and forces them into new plants. Topdress, fertilize and water. Do all of this before July 31.

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