Prevent iron chlorosis from yellowing your turf
A vibrant green blanket of consistent, rich, emerald color characterizes healthy, lush turfgrass. A pale yellow cast across this perfection is like a dark shadow ruining the turf picture. This bleached turf is usually a result of iron chlorosis, a condition that occurs when green chlorophyll in turf tissue fails to develop properly because it lacks iron.
“Although iron is not a part of the chlorophyll molecule, it is one of the nutrients essential for chlorophyll synthesis,” according to the Louisiana State University Ag Center. Understanding of the causes of iron deficiency, as well as all of the possible solutions, can help turf managers correct iron chlorosis problems in turfgrass, turning yellow grass back to green.
Where’s the Iron?
Iron chlorosis first develops in new turf growth and appears as interveinal yellowing in grass blades, giving them a striped appearance. As the condition worsens, leaves appear yellow to almost white.
Telling the difference between an iron deficiency and a nitrogen deficiency can sometimes complicate the correct diagnosis of an iron chlorosis problem. According to explains Bruce Chladny, a horticulture agent in Kansas State University Research and Extension, iron deficiencies show up on the youngest turf blades first and reveal a pale yellow between green veins, whereas nitrogen deficiencies will appear on older leaves and cause overall yellowing.
There are many reasons turf can become iron deficient. Overly compact soils can lead to reduced nutrient uptake. High phosphorous levels, soil pH (greater than 7.2), and excessive irrigation also can limit iron uptake. Additionally, environmental factors, such as temperature, rainfall and light intensity, may influence iron uptake, explains Richard Duble, professor and extension turfgrass specialist, Texas A&M University. Certain turf types are also more susceptible to the problem, such as some species of Kentucky bluegrass, St. Augustinegrass and Bermudagrass.
Many times, the solution to iron chlorosis depends on the cause, Chladny says. For instance, “during cool, wet weather, roots can temporarily shut down, causing symptoms to occur,” he explains. “Usually when the rain stops, the roots start growing and plants have a full recovery. Turning off the water or having the lawn core-aerated works well if the condition is brought on by lack of air movement or by over-irrigation.
Applying iron containing fertilizers can also ease iron chlorosis severity. Liquid or granular applications of iron itself can also help, albeit temporarily, Chladny says.
When soil pH is the problem, the correction is a bit more complicated. Changing soil pH-a longer, slower process-can produce longer-term results, Chladny says. He recommends sulfur applications at the rate of 5 pounds per 1,000 square feet. “Make applications in the early spring and fall until enough sulfur has been added to adequately adjust the soil pH,” he says. “For best results, make the application after the lawn has been core-aerated, and water well.”
KeyPlex nutritional products such as TurfPlex, IronPlex and KeyPlex 350 PTL can help maintain healthy turfgrass. When extra iron is needed, IronPlex is a formulation of chelated iron that contains alpha-keto acids, which may facilitate utilization of micronutrients and increase resistance to environmental stress. It also contains humic acid, which may enhance soil micronutrient availability.