USGA Research Benefits Golfers And Golf Facilities – Part 1 February 17, 2014 By Patrick O'Brien

A bentgrass putting green turf plot at North Carolina State University shows the etiolation of leaves and stems during the summer months.

The USGA Turfgrass and Environmental Research program has funded projects at land-grant universities across the country at a cost of over $40 million since 1920. Three recently funded projects at Clemson and North Carolina State University have been done over the past few years. This web update is the first in a three-part series on how these USGA-funded research projects benefit golfers.

Project Title: Investigations into the Cause and Management of Etiolation on Creeping Bentgrass Putting Greens  

Location: North Carolina State University  

Researchers: David Ritchie and Joseph Roberts  

Summary: Creeping bentgrass remains a popular putting turf used throughout most of the Southeast. An increasing problem in recent years has been yellowing and elongation of bentgrass grass tillers (stems and leaves). This has been termed etiolation. In some cases, these outbreaks cause gradual turf thinning and death of bentgrass during the summer months. Scientists and superintendents have speculated as the reason for this problem, including bacteria, fungi, viruses or nutritional deficiencies.

The focus of this research was to determine the cause and develop management programs for this bentgrass putting green issue. Research done previously at Michigan State University isolated the bacteria Acidovorax avenae from etiolated bentgrass from a North Carolina golf course. North Carolina State University researchers have since identified 16 genera of bacteria, including Acidovorax avenae, from bentgrass turf exhibiting etiolation and general summer decline symptoms. Research has shown that additional bacteria, including but not limited to Xanthomonas translucens, may be capable of infecting creeping bentgrass turf resulting in etiolation and decline during stressful summer periods.

A field study was initiated during 2011 to determine if the use of biostimulants and plant growth regulators contributes to bentgrass etiolation. These products are commonly used on bentgrass putting greens during the summer months. Throughout multiple years of study, biostimulants did not have a significant effect on etiolation development. Astron biostimulant typically had the most etiolation but was often statistically similar to the non-treated control. Plant growth regulators have significantly impacted etiolation development but in different ways depending on the bacterium present causing etiolation. Primo MAXX® reduced etiolation caused by X. translucens in fall 2011. In 2012, the same plots were inoculated with Acidovorax avenae. During this season, Primo MAXX growth regulator enhanced etiolation compared to untreated plots, regardless of biostimulant treatment. Surprisingly, turf decline was not observed in any year of the experiment and Primo MAXX often improved turf quality even when etiolation was observed. Additional research is currently being conducted to evaluate additional growth regulators for their influence on etiolation.

Future research will focus on whether bacteria cause etiolation through direct production of plant hormones or by modifying the plant host to cause turf decline. More studies are needed about the use of Primo MAXX during the summer months on bentgrass putting greens and its impact on turf quality while reducing etiolation. 

What Golfers Should Know  

Golfers should know that multiple species of bacteria can cause this decline on bentgrass putting greens. Although limited management options exist to help with this summer decline problem of bentgrass putting greens, USGA-sponsored research is underway to find a solution.  

For additional information on this USGA research project, please see Investigations into the Cause and Management of Etiolation on Creeping Bentgrass Putting Greens

Source: Patrick O'Brien ( and Chris Hartwiger (

Information on the USGA’s Course Consulting Service

Contact the Green Section Staff