November 1995 - Volume II, Issue 11

Winter Lawn Color

David M. Kopec, Extension Turfgrass Specialist

The "color" of winter turf can tell you a lot about growing conditions and special nutrient requirements during the winter months. Turfgrass plants respond to cold night temperatures, direct frost burn, wet cold soils, and mineral deficiencies differently than they otherwise may do at other times of the year. Here are some of the most common occurrences on turf.

Pale green color, very low clipping production and lack of tillering in overseeded bermuda
Here the ryegrass needs most likely nitrogen. In the coldest time of the year nitrate nitrogen (No-3) is most available. Organic forms and ammonium (NH4+) are much less available and conversion to the nitrate form is very slow during the coldest winter period.

Low cost nitrate forms available are, ammonium nitrate, potassium nitrate, and calcium nitrate. Apply 1/4 lb. -N- per 1000 ft2 as needed, usually once every three weeks.

Straw and/or yellow leaf tips
Straw colored leaf tips may be the result of direct frost damage. The leaves will look they have "dried up", and be slightly twisted. Mowing with a dull or improperly adjusted reel mower will cause similar symptoms, but the leaf blade may have several damage streaks across each blade. Learn the difference and you will never mistake either of these again. Yellow leaf tips associated with frost damage appear as follows. (1) Leaf appears yellow at first, (2) leaf tip is straw and (3) immediately below straw color is slight yellow band.

Yellow Leaf Tips
When the leaves are yellow from the youngest leaf tip downwards, this is usually an iron deficiency. Here each succeeding younger leaf becomes deficient, so the yellowing occurs from the tip of the leaf down towards the base,... then from the next younger leaf tip... to its base, etc.

The iron in the soil is not as available when the soil is cold and wet. This is why the turf in the "wet spots" is usually the most "yellow". Turf can be treated with ferrous sulphate spray, or with cheleated forms which are readily available. Ferrous sulphate is cheaper, but does not last as long. Apply as a spray during the heat of mid-day and let dry on the leaf for 12 to 24 hours.

Dark green turf, stunted with purple colored leaves
The turf appears dark green, with a discoloration of the lower, older leaves. This dark green color of the lower leaves turns to a dull blue-green, followed by a purple discoloration along the entire edge of blade. It is usually more purple on the underside. On some turfgrasses, the purple coloring will change to dull reddish tints that appear on leaf tips first, and then go down the blade. Dead tissue occurs then on the older leaf tips and progresses towards the base.

Apply a high phosphate fertilizer (0-27-0) or (0-45-0) to correct these deficiencies. Apply at a rate of 1.0-1.25 lbs. of phosphorous/1000 ft2.

Like iron, phosphorous is less available under cold wet soil conditions.

Blotchy leafs, with intermittent leaf yellowing or whitening, withered leaf tips
Yellowing occurs between the veins, but the mid-vein retains its green color. The leafs may feel limp and soft. The tips of the older leaves my be yellow-white, and be frayed or cracked. Leaf tips may curl, and some green patches will be left on the leaf. The leaf edges will also be scorched, and tear easily.

Apply a potassium containing fertilizer at the rate of 1.0 lb. -N-/1000 ft2.
Readily available sources include potassium nitrate (13-04-0) or potassium sulphate

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