David M. Kopec, Extension Turfgrass Specialist
It's early winter time and it's down-right cold at night. The overseeded ryegrass may look a little peaked and is slow to grow due to the cold temperatures. Here's what to look for with ryegrass.
1. Overall pale color, along with the lowest two leaves bright yellow. This is most likely a nitrogen deficiency. Remember, the plant requires light frequent amounts of nitrate containing fertilizer (NO_^Ãj‹ÎèÑ·3) when the air and soil temperatures are cold. Nitrate is available in ammonium nitrate (NHy No3), calcium nitrate (Ca (NO3)2), and potassium nitrate (KNO_^Ãj‹ÎèÑ·3). The potassium nitrate has the benefit of potassium, which toughens turf in the cold as well. Applications of 1/4 - 3/8 lb. of nitrate -N- NH4 every three weeks in the dead of winter is usually enough to provide enhanced green color.
2. Pale color, stunted growth, along with purple underside of the leaves and stems. This is usually from a phosphorous deficiency and occurs easily on sand greens in the winter. It can also occur on cold and poorly drained soils. Apply 1.0 lb. of actual phosphorous per thousand square feet.
3. Yellow leaf tips. This can be caused by mowing the grass when it is cold, especially with a dull mower. Usually, the very end of the leaf tip will be dark brown for about 1/16 of an inch downward. If the leaves are more gradually yellowing from the tips downward, starting from the newest (youngest) leaf, then iron applications may be necessary. Iron is not taken up readily in cold and wet soils, even on fairways which have a fair amount of iron in the soil. Ferrous sulphate is an inexpensive fix, but most of the iron will soon become tied-up in the soil. On a few tees and greens, try a cheleated iron. It is more expensive but lasts longer. Spray iron on in the heat of the day and try not to irrigate that night.
4. Broadleaf weeds like yellow rocket and burr clover can be problems along paths and tee slopes. Use broadleaf post emergent herbicides at label rates.
5. Poa annua is mans worst friend. On overseeded bermuda use PROGRASS (ethofumosate is the active ingredient) at the label rate. Make applications "before February 1st" as stated on the label. If you wait longer, you may run the risk of damaging semi-dormant bermuda.
On non-overseeded areas you may have plenty of Poa if you did not use a pre-emergence. Di-QUAT is effective as an inexpensive way to remove annual bluegrass non-selectively.
On bentgrass greens, Poa is your nightmare. If Bensulide pre-emerge didn't work, you may experiment with plant growth regulators. Notice the work "experiment". Some superintendents have used Scotts TGR (paclobutrazol is the active ingredient), while some have tried PROGRASS at light rates. Check the label. Some superintendents have had some success using cutless. Again, check the label.
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.