Fighting a new foe

Golf course superintendents are no strangers to battling turfgrass diseases, which are top of mind daily – whether fighting an outbreak or spraying preventively.

Greens at the Santa Ana (Calif.) Country Club were some of the first that showed the effects of rapid blight.

Snow mold is common in the Northeast United States. Fairy ring can be found throughout the prairie states. But what happens when a disease makes its presence known in an area for the first time? Emerging diseases aren’t recognized easily, so it’s important superintendents treat one correctly, or the results could be disastrous.

Dave Zahrte, certified golf course superintendent at Santa Ana Country Club in Southern California, dealt with an emerging disease. He sprayed his greens with a broad-spectrum fungicide on a Friday and went about his normal schedule. During the weekend, his assistant superintendent noticed something on the 15th green that looked strange. When Zahrte returned to the course Monday morning and looked at the green, 35 percent of it was affected by something new.

“It looked like nothing I’d ever seen before,” he says. “It just didn’t look right. I couldn’t figure out what the heck it was.”

Like Zahrte, Michael Coranci, superintendent at Candlewood Country Club in Whittier, Calif., also battled a mysterious disease on his Poa annua greens. He noticed the affected areas in late spring when he was preparing the greens for the hot season and started hearing about other courses in the area that began getting it shortly thereafter.

“They looked like dry patches on the green – with no specific configuration,” he says.

Both men later learned the disease was rapid blight.

Hunt for a cure
Larry Stowell, Ph.D., of the PACE Turfgrass Research Institute, was called in on both cases.

In a research paper submitted to the American Phytopathological Society, Stowell writes, “the foliage of the affected turf was yellow and brown and had a water-soaked appearance, while the roots of the plant seemed unaffected.”

Turfgrass researchers such as Larry Stowell, Ph.D., took a close look at rapid blight samples.

Under the microscope, the samples revealed none of the usual winter time Poa diseases such as Fusarium patch, and there were no obvious signs of fungal pathogen invasion such as mycelia or spores. No insect or nematode pests nor the damage they cause were observed, and nutritional and cultural problems such as anaerobic soils or nutrient imbalances also were eliminated as possible causes.

With samples now coming from California, Colorado and Nevada, the search for a diagnosis and cure broadened. The late Houston Couch, Ph.D., of Virginia Tech was contacted for input on potential control strategies. He suggested mancozeb might be an effective control agent because of its mode of action as a general membrane disruptor. Shortly after, mancozeb became the first recognized treatment for prevention and to limit spread of the disease.

It was recommended to Zahrte that he apply mancozeb and put down a towel to keep one spot as a test plot. The spraying didn’t have an immediate impact, but within three or four weeks, the blemishes went away, he says.

But golf course superintendent Kurt Desiderio, a PACE working group member from Saticoy Country Club in Somis, Calif., was frustrated by the incomplete control of the disease using mancozeb. He found trifloxystrobin (Compass) effective in stopping the disease.

Clemson University’s Bruce Martin, Ph.D., who was brought in to the discussion when a course in South Carolina submitted a sample, followed Desiderio by combining Compass and pyraclostrobin – which was soon to be labeled as Insignia. In 2003, Insignia was labeled for turf disease control and included rapid blight on the label.

The study resulted in the following conclusions:
• Most, but not all, cases of rapid blight disease have been associated with saline irrigation water and an accumulation of salt in the soil;
• The most effective chemicals for preventing rapid blight identified so far are pyraclostrobin (Insignia), trifloxystrobin (Compass) and mancozeb (Fore, Protect); and
• Compass or Insignia mixed or rotated with mancozeb provides good control if applied preventively, while curative applications of chemicals might contain the disease but do not eradicate it.

Studies show rapid blight has affected a range of cool-season turfgrasses in several Western and Southeastern states. Most have shown an increased severity of symptoms as soil salinities increase – many because of the use of poor quality irrigation water. Soil salinity problems might increase in the future as competition for high-quality water, increased use of recycled water and drought conditions occur.

Coranci, who says one of his greens was almost 80 percent affected, was hesitant to spray before he knew exactly what disease he was dealing with. He was relieved to hear the diagnosis.

“I don’t like to spray unless I really know what’s going on,” he says. “The greens got pretty ugly. They looked pretty bad. We didn’t lose any turf, but it sure looked bad.”

Still searching
Zahrte, Coranci and other superintendents who’ve faced rapid blight now have definitive answers, but that’s not the case for Ryan Batz, superintendent at Trump National in Bedminster, N.J.

Turfgrass researchers throughout the country were called to look at Santa Ana Country Club's diseased greens.

Batz battled a mysterious turf condition in September and October of 2005 on several greens and tees. Some cases were severe, and others were minor. Though it was never officially diagnosed, it’s thought to be a relative of take-all patch.

A little more than three weeks after a hollow core aerification, Batz noticed blemishes on the 14th and 15th greens. Batz says he changed pins Sept. 17 and saw nothing on the eighth green. The following day there were a few patches, and by the third day, it was a full-blown outbreak on the eighth green and increased activity on several other holes. Banner Maxx and Daconil Ultrex were applied, but resulted in little change.

Bruce Clarke, Ph.D., at Rutgers University and Paul Ramina, superintendent at Hamilton Farm Golf Club in Long Valley N.J., were among the turfgrass professionals to examine the condition while visiting Trump National.

Initially, the disease was thought to be bentgrass dead spot, but when samples were checked in the labs, dead spot was ruled out. Batz says the spots appeared to be two-inch blemishes that were bleached in the middle and had a yellow ring on the outside. A mobile disease, it seemed to affect the higher areas of the greens and worked its way down to lower sections, according to Batz.

In addition to the visits, Batz sent samples to Clarke and Turf Diagnostics in Westchester, N.Y. Upon the recommendations of turfgrass professors, he also applied Insignia and then Medallion, but again with little success.

More samples were sent to the University of Maryland, University of Georgia, North Carolina State University and the Chicago U.S. Golf Association for testing Sept. 21.

With the problem persisting, the staff applied Terrazole and Banol.

When Batz received the results of the soil samples, he saw high pH ranges of 6.8 to 7.1 on the infected greens. Potassium sulphate was applied to correct the pH level, and within a week the symptoms were relieved.

“That’s going to be our starting point from now on,” Batz says of checking the soil conditions for a healthy pH range.

In addition to bentgrass dead spot, rapid blight and pythium were considered as possibilities before deciding on a relative of take-all patch.

Pythium root dysfunction
At North Carolina State University, Lane Tredway, Ph.D., has been working for the last few years on an emerging disease he’s calling Pythium root dysfunction.

Trump National Golf Club in Bedminster, N.J., was hit with a mysterious disease that is thought to be a relative of take-all patch.

“We suspect the pathogen is Pythium volutum, and we’re in the process of verifying that scientifically,” he says. “This disease has become a widespread problem for golf course superintendents in North Carolina and other Southeastern states. The disease specifically attacks newly constructed putting greens. The susceptibility of the turf seems to decline six to eight years after establishment.”

It’s early, but Tredway thinks he has a grasp on the disease.

“Based on our observations, Pythium volutum attacks the creeping bentgrass roots in the fall and spring when they are actively growing,” he says. “However, no symptoms are usually seen at this time. Turf stress – from heat, drought, low mowing, nutrient deficiency, etc. – is required to induce symptom expression. As a result, symptoms are most common and severe during the summer months.

“This problem has been brought on by an increase in new green construction and the use of excessively well-drained root-zone mixes,” he adds. “These mixes hold very little water and nutrition, and as a result the turf becomes much more susceptible to these root infections.”

Superintendents have been able to manage this problem with an integrated approach including fungicide applications and cultural practices, Tredway says. Cultural practices include increasing mowing heights, increasing fertility levels, avoiding severe drought stress and regular cultivation to control organic matter levels.

“The most effective fungicide for control of this disease has been pyraclostrobin (Insignia),” Tredway says. “Some efficacy has also been seen from azoxystrobin (Heritage), fosetyl-Al (Signature), and mefanoxam (Subdue Maxx).”

These products can be used on a curative basis when symptoms appear or on a preventive basis in the fall and spring, according to Tredway.

Advice
When dealing with emerging diseases, superintendents should seek help right away. Batz says he and director of grounds Greg Nicoll were fortunate to have the support of the membership and green committee through the entire process.

“Contact somebody,” he says, pointing to the tight-knit fraternity within the golf industry. “Have them come over and see what they see.”

Coranci, who has stayed on a preventive program, advises superintendents to not take this on themselves. Seek help.

“Get it diagnosed,” he says. “Too many times people spray the wrong thing.
“We’re educated to take care of the turf, but we’re not plant pathologists,” he adds. “If you see something that looks weird, take care of it.”

Maintaining an ongoing dialog with club management, the green committee and concerned members is important. Also, communicating with outside turfgrass professionals is key to overcoming an emerging disease. GCN