Bacterial Wilt of Bentgrass...

I am posting this an "emergency post" since we are all getting a lot of phone calls about it. This message is from Dr. Nathaniel Mitkowski at the University of Rhode Island. Dr. Mitkowski is an expert in bacterial wilt of annual bluegrass.

Bacterial Wilt of Bentgrasses (by Nathaniel Mitkowski, Ph.D.)

The first time bacterial wilt was identified from bentgrass was in the 1970’s. The pathogen, Xanthomonas translucens pv. graminis, only seemed to infect the Toronto C15 variety. This variety was planted primarily around the Chicago area and could rapidly kill turf. Since then, this bacterial species had been sporadically identified but has not been observed causing much damage. In 2003 I found the pathogen in Pawtucket, Rhode Island but it was essentially nonsymptomatic.

In June of 2009, a new bacterial wilt was identified on Penn G2 greens at [Golf Course name removed for confidentiality} North Carolina. The pathogen caused severe etiolation of leaf blades. The isolated bacteria was identified by Dr. Joseph Vargas at Michigan State as Acidovorax avenae subsp. avenae and resulted in wilting and senescence of plants when inoculated in the laboratory. Reports from [golf course] this summer indicate that the bacterium is still causing problems and some turf is being lost. The first report of the pathogen can be found here:

Bacterial Wilt on bentgrass from Dr. Vargas

In the past week, bacterial wilt of bentgrass has been identified at the URI Disease Diagnostic Laboratory at least a dozen times. The bacterium has been identified on L-93, SR1119, and velvet bentgrass. Reports of the pathogen on A4 have also come in. The disease will likely go to any variety of bentgrass. Symptoms include: etiolation, small to medium sized patches of weak turf, turf with excessive senescence and dead plants.

While etiolated turf has been identified from New England golf courses in the past, I have never been able to isolate bacteria from previous samples. The samples I am observing this year are full of bacteria at levels that I have not seen in the past. It seems highly probable that this bacterium requires extended high temperatures and humidity, weather common to the Southeast and similar to the weather pattern experienced in New England over the past 2 months. Superintendents who described seeing this disease in previous years mention that it often goes away completely when daytime temperatures drop into the 70 degree range. It does not appear that a break in the weather is imminent but if it occurs, plant recovery should follow.