As new chemicals to fight anthracnose proliferate, so does the disease. The combination of warm winters, hot summers, lower cutting heights and leaner greens has led to increased outbreaks of anthracnose over the last few years.
“It used to be a hot-weather phenomenon, but it has become a disease that starts up in the spring,” said Dr. Gail Schumann from the University of Massachusetts. “I need to put a thing on my phone that says, ‘If you are calling about anthracnose, press 2.’”
According to Schumann and other turfgrass pathologists, the disease that attacks Poa annua and has even been seen on bentgrass, is becoming more prevalent and more difficult to control because of increasingly stressful cultural practices.
“Turf management has changed,” she said. “The key things are lower mowing heights and more compaction from increased play and the sand topdressing that gets brushed in. I think it is a signal from the turf that they [courses] are going too far. You can throw every kind of chemical in the world at it, but if you don’t modify those cultural practices you are going to still be dealing with it.”
According to Rutgers University’s Dr. Bruce Clarke, maintaining proper levels of fertilization, raising the height of cut and maintaining consistency are the keys to managing anthracnose culturally.
“Superintendents need to get off the mowing roller coaster,” he said. “Going back and forth and raising it and lowering it again and again in the heat of the summer is difficult on turf. Greens can still be fast and have less disease but it is a compromise that needs to be made because you can’t keep lowering the height of cut forever.”
Weather, however, has also played a part in the severity of the disease pressure. Warmer winters in 2000 and 2001 allowed the pathogen to survive and hit earlier than before. Hot, drought-plagued summers served to worsen conditions.
ROTATION IS KEY TO CONTROL
While anthracnose wreaked havoc on courses last year, it yielded valuable information to those studying the disease that will be helpful in future outbreaks.
“Last year was the best fungicide study I have had in the last 20 years because it was very easy to evaluate,” said Clarke. “We got a natural infection.”
Clarke’s research took place at three different sites and confirmed the importance of rotating fungicides to control the disease and reduce the chances of resistance.
“In the study, we had tolerance from strobilurins and benzimidazoles but at other courses they worked just fine,” said Clark. “So you can’t say they don’t control anthracnose, that is not the point. Many courses have had success with those two chemistries. This is why we need to tank mix and rotate. Where strobilurins and benzimidazoles are affected they should be alternated with other products.”
Superintendents have taken the rotation suggestion seriously, and many have reported success.
Bob Mogel, superintendent at Galen Hall Country Club in Wernersville, Pa., got hit hard in 2001 and was ready for anthracnose in 2002. His arsenal included Signature, Zerotol, Daconil, Compass and Banner MAXX and he managed to make it through 2002 unscathed.
“It hit in the end of March a couple of years ago, so I started off early last year. I am about to put out Zerotol pretty soon here. It smokes the spores with hydrogen dioxide. Last year I sprayed every Friday throughout the summer. I used a lot of Signature and Daconil and threw in some triple 20 fertilizer to keep the fertility up,” he said.
Mogel also tried not to stress out the turf. He started the season at 1/10 of an inch and eventually went up to 1/8 of an inch. He also used solid rollers and stayed away from aerifying or verticutting after the beginning of May.
Down at Doylestown Country Club in Warrington, Pa., superintendent Paul Bevan has managed to stay anthracnose free as well while also keeping the greens lean and mean.
“When I came here we had six greens that were riddled with it,” said Bevan. “Right now we don’t have any.”
Bevan has reduced fungicide applications to twice a month by rotating applications between Zerotol every other week and a mixture of fungicides every other week. Last year he used Daconil, 3336, Compass, Alliette, Heritage, Banner MAXX, Bayleton and Endorse.
“I mow greens at 1/10 of an inch and I roll three times a week,” said Bevan. “I push them and I have not had any problems with it. When I have had little bouts of it, five or six spots on each green, I hit it with Zerotol for three straight days and then come back with Endorse or Daconil and I seem to get some recovery out of it.”
While superintendents continue to press the envelope, more research is planned. Clarke will focus future research on the impact of fertility, mowing practices, plant growth regulators, herbicides and improved fungicide application strategies on the development of anthracnose.
“It used to be a hot-weather phenomenon, but it has become a disease that starts up in the spring,” said Dr. Gail Schumann from the University of Massachusetts. “I need to put a thing on my phone that says, ‘If you are calling about anthracnose, press 2.’”
According to Schumann and other turfgrass pathologists, the disease that attacks Poa annua and has even been seen on bentgrass, is becoming more prevalent and more difficult to control because of increasingly stressful cultural practices.
“Turf management has changed,” she said. “The key things are lower mowing heights and more compaction from increased play and the sand topdressing that gets brushed in. I think it is a signal from the turf that they [courses] are going too far. You can throw every kind of chemical in the world at it, but if you don’t modify those cultural practices you are going to still be dealing with it.”
According to Rutgers University’s Dr. Bruce Clarke, maintaining proper levels of fertilization, raising the height of cut and maintaining consistency are the keys to managing anthracnose culturally.
“Superintendents need to get off the mowing roller coaster,” he said. “Going back and forth and raising it and lowering it again and again in the heat of the summer is difficult on turf. Greens can still be fast and have less disease but it is a compromise that needs to be made because you can’t keep lowering the height of cut forever.”
Weather, however, has also played a part in the severity of the disease pressure. Warmer winters in 2000 and 2001 allowed the pathogen to survive and hit earlier than before. Hot, drought-plagued summers served to worsen conditions.
ROTATION IS KEY TO CONTROL
While anthracnose wreaked havoc on courses last year, it yielded valuable information to those studying the disease that will be helpful in future outbreaks.
“Last year was the best fungicide study I have had in the last 20 years because it was very easy to evaluate,” said Clarke. “We got a natural infection.”
Clarke’s research took place at three different sites and confirmed the importance of rotating fungicides to control the disease and reduce the chances of resistance.
“In the study, we had tolerance from strobilurins and benzimidazoles but at other courses they worked just fine,” said Clark. “So you can’t say they don’t control anthracnose, that is not the point. Many courses have had success with those two chemistries. This is why we need to tank mix and rotate. Where strobilurins and benzimidazoles are affected they should be alternated with other products.”
Superintendents have taken the rotation suggestion seriously, and many have reported success.
Bob Mogel, superintendent at Galen Hall Country Club in Wernersville, Pa., got hit hard in 2001 and was ready for anthracnose in 2002. His arsenal included Signature, Zerotol, Daconil, Compass and Banner MAXX and he managed to make it through 2002 unscathed.
“It hit in the end of March a couple of years ago, so I started off early last year. I am about to put out Zerotol pretty soon here. It smokes the spores with hydrogen dioxide. Last year I sprayed every Friday throughout the summer. I used a lot of Signature and Daconil and threw in some triple 20 fertilizer to keep the fertility up,” he said.
Mogel also tried not to stress out the turf. He started the season at 1/10 of an inch and eventually went up to 1/8 of an inch. He also used solid rollers and stayed away from aerifying or verticutting after the beginning of May.
Down at Doylestown Country Club in Warrington, Pa., superintendent Paul Bevan has managed to stay anthracnose free as well while also keeping the greens lean and mean.
“When I came here we had six greens that were riddled with it,” said Bevan. “Right now we don’t have any.”
Bevan has reduced fungicide applications to twice a month by rotating applications between Zerotol every other week and a mixture of fungicides every other week. Last year he used Daconil, 3336, Compass, Alliette, Heritage, Banner MAXX, Bayleton and Endorse.
“I mow greens at 1/10 of an inch and I roll three times a week,” said Bevan. “I push them and I have not had any problems with it. When I have had little bouts of it, five or six spots on each green, I hit it with Zerotol for three straight days and then come back with Endorse or Daconil and I seem to get some recovery out of it.”
While superintendents continue to press the envelope, more research is planned. Clarke will focus future research on the impact of fertility, mowing practices, plant growth regulators, herbicides and improved fungicide application strategies on the development of anthracnose.
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