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GRAY LEAF SPOT IN CENTRAL IOWA

October 2, 2012

On September 4, I put up a post warning that Gray Leaf Spot might show up in Iowa because of the unusually warm conditions around labor day.

On the 4th I wrote the following:
"This disease is caused by the fungi Pyricularia grisea. It seems to selectively hit perennial ryegrass on intensely managed areas such as golf course fairways and sports fields. Under the right conditions, it can be more devastating than Pythium blight. When it hits, it can wipe out large areas of turf overnight.  Fungicides, such as Banner/Daconil will control it, but they must be applied before the outbreak.  Once the disease begins, it is too late to apply.  The reason I bring this up is that we are in the same weather pattern again this year.  The disease does not always occur when its hot around Labor Day, but it did last year and I would watch for it this year".

What I didn't know at the time was that it would be me that would get hit with the gray leaf spot.  When I went out to take data on the perennial ryegrass trial at the research station in mid September I found that the ryegrasses in the trial appeared to have collapsed.  They looked terrible.  I then looked at two other areas of perennial ryegrass on the site and saw that it looked the same.  Andrew Hoiberg, who recently graduated with his Ph.D. was at the station at the time and commented that it looked like gray leaf spot.  On closer inspection, that is what it appears to be.  It was right on time, shortly after Labor Day during an unusually warm spell.

This trial is part of the national turfgrass evaluation trials (NTEP) and we purposefully do not treat it with fungicides.  The damaged cultivars are beginning to show some recovery as of the beginning of October, but they are still showing signs of the damage.  Under normal conditions, we would simply reseed into the ryegrass and we would have it back in a couple of weeks.  We are unable to do that here because of all the different varieties that are involved.  We will have to wait for recovery.

By the way, is it Gray Leaf Spot or Grey Leaf spot?  You will see many examples of each if you search the internet.  I'm using Houston Couch's book as my source and going with Gray.

The pictures below are of the site in mid September when the damage was most severe.  The first three are of the NTEP perennial ryegrass trial.  The last four are closeups of the damage.

 

 

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ANOTHER GRAY LEAF SPOT WARNING

September 4, 2012

A year ago, on August 31, 2011, I put up a post warning about Gray Leaf Spot on perennial ryegrass.  This disease shows up rather infrequently in Iowa, but it does occur around Labor Day on years when temperatures are unusually high.  Last year's Labor Day temperatures were in the 90's and if you check the post from September 19, 2011, you will see that it did occur on several golf courses with perennial ryegrass fairways.

This disease is caused by the fungi Pyricularia grisea. It seems to selectively hit perennial ryegrass on intensely managed areas such as golf course fairways and sports fields. Under the right conditions, it can be more devastating than Pythium blight. When it hits, it can wipe out large areas of turf overnight.  Fungicides, such as Banner/Daconil will control it, but they must be applied before the outbreak.  Once the disease begins, it is too late to apply.

The reason I bring this up is that we are in the same weather pattern again this year.  The disease does not always occur when its hot around Labor Day, but it did last year and I would watch for it this year.

The pictures below were taken in 1998 on Willow Creek Golf Course in Des Moines and last year on Cedar Poine golf course in Boone. The dead grass is perennial rye and living grass is Kentucky bluegrass.

If anyone has an outbreak of Gray Leaf Sport this year, let me know and send some pictures. 

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GRAY LEAF SPOT DID SHOW UP IN CENTRAL IOWA

September 19, 2011

On August 31, I posted a blog titled "Watch Out For Gray Leaf Spot".

It did show up.  Here is a post from Cory Johnson, Superintendent of Cedar Pointe Golf Course in Boone, Ia.  This is Gray Leaf spot.  It showed up on September 8.  These pictures are from Sept. 16.  This is classic Gray Leaf Spot on perennial ryegrass fairways.  They will need to reseed with ryegrass as soon as possible.

If anyone else has experienced this, send me some pictures.  I suspect that there is more out there.

The first two pictures are fairway shots.  It is the rye that died and there is some live Kentucky bluegrass.

Picture 3 shows a close up of live bluegrass in dead rye.

Picture 4 shows leaf symptoms on the rye.

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WATCH OUT FOR GRAY LEAF SPOT

August 31, 2011

Those of you who have been around since the 90's will remember a major outbreak of Gray Leaf Spot on perennial ryegrass in 1998. This disease is caused by the fungi Pyricularia grisea. It seems to selectively hit perennial rye. Under the right conditions, it can be more devastating than Pythium blight. Like Pythium, it can kill large areas of turf over night.

In 1998, it wiped out perennial rye from Chicago to the Rocky Mountains. It was particularly hard on ryegrass golf course fairways and sports fields.

The conditions that set it off in 1998 were unusually high temperatures around Labor Day. We have not seen a major outbreak of this disease in 13 years, but tomorrow it is predicted to reach near 100 F. That is very hot for Iowa in September. If you have perennial rye that has not been treated with a fungicide, you may wan to be on the look out for this problem. Banner/Daconil was particularly effective against Gray Leaf spot in the 1998 outbreak, but there are other materials labeled for it as well. Check the label before you spray.

The pictures below were taken in 1998 on Willow Creek Golf Course in Des Moines. The dead grass is perennial rye. The only living grass is Kentucy bluegrass that was intermingled in the fairway and some patches had been used to sod around some of the heads.

Let me know if any of you see this in the next few days. Send some pictures if you do.

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