When we talk about scalping Bermuda lawns it almost always is done in the spring. However, as the summer passes along our Bermuda grass gets taller and taller. When this happens we get a small percentage of GREEN blade on the top, but below lies brown and yellow stems. When you cut, some of this yellow / brown will show through. Doing a HARD CUT… or 1/2 scalp will help cure this issue. Just be careful not to do this during droughts or without control of the water.
Below you will see some yellow blades of grass. This is mainly the result of chlorosis. More below…
Too many people are applying high phosphorus fertilizers and doing so over and over and over… this leads to phosphorus build up and can cause chlorosis in lawns.
University and Extension Studies…
“Chlorosis can also be a symptom of more permanent problems like improper soil pH and an elevated level of soil phosphorus. A soil test can confirm the cause of yellowing.”
“The buildup of phosphorus in lawns, gardens, pastures and croplands can cause plants to grow poorly and even die. Excessive soil phosphorus reduces the plant’s ability to take up required micro nutrients, particularly iron and zinc, even when soil tests show there are adequate amounts of those nutrients in the soil.” Read More
“Iron chlorosis results when green chlorophyll in leaf tissue fails to develop. Although iron is not part of the chlorophyll molecule, it is one of the nutrients essential for chlorophyll synthesis. Iron chlorosis first develops in new growth and appears as yellowish-green leaves, usually as an interveinal yellowing, giving the leaf a striped appearance. As the condition worsens leaves appear yellow to almost white. In severe cases of iron chlorosis, loss of turfgrass and other plants occur in irregular patterns.”
Iron chlorosis is attributed to reduced availability of iron in calcareous soils and may also be associated with high levels of bicarbonate and phosphate in plant tissue.” Read More