Etiolated or rapidly elongating leaves on turfgrasses are a problem that we’ve encountered more of recently. Hot and somewhat cloudy weather appears to be the environment that favors this turfgrass phenomenon. Turfgrasses showing these symptoms have included annual bluegrass, Kentucky bluegrass, perennial ryegrass and creeping bentgrass so far. Etiolated leaves appear yellow and tend to extend 2.5 to 5.0 cm (1-2 inches) above the turf canopy. The leaves eventually become bleached out (white) due to the dilution of chlorophyll in the rapid elongating leaves.
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This phenomenon has been reported as Mad Tiller Disease, and Ghost Grass (primarily in the United Kingdom). Recently, the term “Etiolated Tiller Syndrome”(ETS) is being used.
The cause of ETS is not well understood or a definite reason given for why it occurs. Speculation on the cause has included bacterial wilt, micronutrient deficiencies and increasingly on the fungus, Fusarium moniliforme that causes similar symptoms in rice. The fungus produces gibberellic acid (GA) – like compounds which is associated with the leaf elongation. Etiolation – the extension of the leaf blades upward – is a common growth occurrence of plants under low light conditions. It is possible under extended cloudy wet conditions that the leaves elongate in response to the low light conditions favoring infection by F. moniliforme causing the rapid elongation.
There has also been some suggestion that ETS is a response to consistent use of plant growth regulators, but many of the turf areas showing signs of ETS (like athletic fields) have never been under regulation.
There does not appear to be any long-term decline in the density or quality of turf from ETS. Additionally, there are no management practices associated with enhancing or promoting ETS. Research observations at Purdue University have found no associated occurrence or control of ETS with GA inhibiting plant growth regulators (ex. Trinexapac-ethyl, flurprimidol, and paclobutrazol). It would appear then that applying a GA inhibitor like trinexapac-ethyl may not control the ETS problem. Masking the problem with color enhancing fertilizers may also not help.
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The scientific community does not have an answer to the ETS phenomenon yet, but there have been initial reports of some success at controlling ETS by applying a micro-nutrient package. Research continues.
Thanks to Dr. Cale Bigelow, Purdue University.
Posted by Pam Sherratt & Karl Danneberger, www.buckeyeturf.osu.edu