Is it Poa or Yellow Tuft?

Last week I was touring a golf course with the Superintendent and we had a discussion about yellow spots on one of their putting greens. Yellow spots can be the result of a number of diseases and conditions. Poa annua contamination and yellow tuft were the first two possibilities that came to mind. Being able to correctly identify the problem is very valuable as the fungicides labeled for yellow tuft can be costly.

This particular green is grassed with the new, high-density bentgrass cultivars. Many of the new bentgrasses are genetically darker green compared to the older cultivars. As a result, any poa that is present is even more distinguishable within the canopy. This color difference can easily be misdiagnosed as a disease and could be the cause of the yellow spots.



Like most diseases, yellow tuft seems to be most prevalent in areas that are poorly drained, over-irrigated, or have excessive thatch. This green is rather flat and has relatively poor surface drainage. The weather so far during the month of June has provided plenty of moisture with many parts of the state receiving over 5 inches of rain.

I collected some samples of the affected turf for further inspection. I was able to detect a fair amount of poa within the samples. The poa could be contributing to the yellow appearance but might not be the sole cause as yellow tuft can occur on most turfgrass species although it is most common in creeping bentgrass or annual bluegrass. Digging a little deeper, I was able to find clusters of tillers originating from a single crown. This symptom is characteristic of yellow tuft and is the result of a plant hormone released by the disease pathogen.





In this case, even though poa was present in the canopy, the yellow spots were probably mainly the result of yellow tuft. With all the rain most parts of the state have received the conditions that would favor yellow tuft development are favorable. Cultural controls for yellow tuft include ensuring adequate surface and subsurface drainage. As far as chemical controls, the mefanoxam (Subdue Maxx) and fosetyl-Al (Signature) are the only fungicides currently labeled for yellow tuft.

For a great article about other causes of yellow spots on putting greens check out this link to our friends at the Turf Disease Blog. Let’s hope the rain stops and the soil dries out a bit before the temperatures heat up again.

Marcus Jones
Graduate Research Assistant

FIRST PYTHIUM I'VE SEEN THIS SEASON

This is the first Pythium I've seen this season. Chicago, June 12, 2010. 86 in the afternoon, followed by upper 60's the night before.

Chloroneb knocked it dead.

LIGHTNING STRIKE AT MAKRAY GOLF COURSE IN ILLINOIS

The following is a post from Tim Christians, Supt. of Makray Golf Course in the Chicago area. It happened last week during a thunder storm. Lightning hit above an irrigation line (there was no head above ground at this location) and shattered the underground pipe. You can see pieces of plastic on top of the ground.

Poa Control with Covers?

Last week I stumbled across something I have never seen before. The picture below shows a bentgrass/poa putting green with distinct lines spanning lengthwise across the green. I have observed dark green lines appear beneath the seams of covers shortly after removing the covers in the spring. The line in this picture is the result of a shift in grass species; the dark line is creeping bentgrass. It appears that the microclimate created directly beneath the seam of the cover allowed the bentgrass to outcompete the poa. More of these “lines” were visible on this green but not all greens on the course displayed this same response. I would be interested to know if anyone else has ever observed this before.
























Marcus Jones
Graduate Research Assistant

Poa annua CONTROL AT GREEN BAY CC

Poa annua Control Trials at Green Bay C.C.

Marc Davison, CGCS

Green Bay Wisconsin

Green Bay Country Club is 16 years old. I have been working hard trying to keep the Poa annua out, or at least under control, since the course was built. I have used Prograss, Velocity, TGR, Cutless, and pre-emergence herbicides, etc. over the years. Nothing has ever convinced me to keep going on a program because of the poor results I always get. Half our fairways were originally seeded to Pennway creeping bentgrass and the second half to Providence creeping bentgrass. In 2009 we had approximately 5% Poa annua.

During the summer of 2009, I decided to get as aggressive as I have ever been. On May 22, 2009, I treated all of our fairways with a full rate of TGR 31-3-6. That is 32 oz/ac of Paclobutrazol and 0.85 lb. N/1000 ft². That was the first time I ever applied that much TGR over all of our fairways.

In July, I started applying Velocity at various rates and at various frequencies. I wanted to incorporate all the different approaches I have read about, including the “quick reduction” and the “slow reduction” programs. I applied Velocity twice at a 6 oz/acre rate and 14 days apart on six fairways. I followed these applications with 2oz/acre Velocity, also on two week intervals. In total, I ended up with a few fairways. receiving 14oz/acre (6+6+2 oz), a few fairways getting 18oz/acre (6+6+2+2+2 oz), one fairway just got the two 6 oz. applications. Thirteen fairways received no Velocity.

One of my 18 oz/acre fairways also got a second application of TGR on Aug. 18^th at full rate. This fairway received a total of 64oz/acre paclobutrazol and 18oz/acre Velocity. This fairway was treated with the highest rate of chemical of any fairway in the trial.

My observations in 2009:

1. There were several interesting color changes in the fairways. The Velocity turned the bentgrass a very lime green color, which is not a problem unless you skip an area. Then the color difference is obvious.

2. The Velocity treated fairways looked very droughty towards the end of summer. Kind of sick and worn out looking.

3. I did not observe any noticeable differences in Poa annua populations between any of the treatments in the fall of 2009.

In the spring of 2010, I was hoping to see some real differences in Poa annua infestation among the fairways. I waited until seed head formation before drawing any conclusions. The spring of 2010 has been a banner year for seedhead formation on the Poa annua. Unfortunately, I could see no difference in Poa annua infestation between the untreated fairways and any of the treated fairways.

The only place that I noticed any damage to Poa annua was on small areas of three of the greens. It took a month before I figured out what had caused this. While spreading TGR on our green collars last summer, I grabbed handfuls of the material from the spreader and hand sprinkled it directly on the small Poa patches in these three greens. I saw no ill effects last summer or fall, but this spring it was obvious something had been applied in these specific areas.

What are my plans during the 2010 season? I am going to spray 8 oz. paclobutrazol and 4 oz Primo on all our greens and fairways at three week intervals beginning the week of June 7^th. I have already applied TGR 31-3-6 at half rate on all fairways.

I still am not convinced that any of this is worth the cost in labor and material. The Poa annua population keeps growing. I am willing try just almost anything, but I am unwilling to waste money if it’s not working.

I would like to hear from other superintendents concerning their experience in controlling Poa annua.

I can be reached at:

mdavison@greenbaycc.org

or

920-339-4640

Or you can post your results on the blog by sending an e-mail to Nick Christians at

nchris@iastate.edu.

Thanks for your time.

HORTICULTURE FIELD DAY-JULY 29

The ISU Horticulture Field Day will be Thursday July 29 at the Horticulture research station. For registration information, see http://www.hort.iastate.edu/news/.

Field Day presentations

1. Wine Lab. The Midwest Grape and Wine Industry Institute will discuss wine grape harvest parameters and their importance to winemaking. The measurements of pH, Titratable Acidity, and Brix will be demonstrated.
2. Computer Applications in Horticulture

This will be a hands-on session covering the latest in software development for the landscape industry. There will be a presentation that will include traditional computer applications as well as iPhone/iPod Touch/iPad applications.

3. High Tunnels. High tunnels extend the growing season and produce greater yields of high quality fruits and vegetables. You will get the chance to see both fruits and vegetables growing in different sized high tunnels.
4. Crabapples. Since 1985, the Iowa State University Department of Horticulture has participated in the National Crabapple Evaluation Program, and during this tour stop we will feature some of the best crabapples for the Iowa landscape. Join us as we traverse this impressive collection in search of that perfect crabapple.
5. Chainsaw safety. You will be learning the strategies to keep yourself and others safe when working with chainsaws.
6. Vineyard. Field day attendees will tour research vineyards that include wine grape cultivars, cropping and canopy management studies, and weed control and soil quality management projects. Iowa State University faculty and graduate students will provide tours and answer viticultural questions.
7. Orchard (3 presentations)

Rootstock/Cropping levels study
This orchard study on 'Gibson Golden Delicious' apple evaluates the performance of five dwarfing apple rootstocks subjected to under different cropping levels. Treatments are being monitored for differences in fruit growth rate, maturity, yield, fruit size and quality, and the ability to produce blossoms for next season's crop.

Airblast Spraying
Airblast sprayers offer an effective and economical means for applying fungicides, insecticides, growth regulators and foliar nutrients in orchards and vineyards. Compared to conventional sprayers, airblast systems allow growers to concentrate spray where less liquid is applied per acre, and at higher concentrations, less pesticide is needed to attain effective coverage. Dr. Domoto will be explaining how this is accomplished, and an airblast sprayer will be demonstrated.

Disease monitoring in Apples
This study is evaluating remotely estimated weather as a warning system for sooty blotch and fly speck on apples.

8. Aquatic Research Facility
   The discussion will focus on current research on fish production with an emphasis on this year's Bluegill project.


9. Vegetables (2 presentations)

   This research looks at the impact of row covers on disease and insect suppression on
   muskmelons and butternut squash.
   
   As part of a multi-state project, we are looking at "flora provisioning" as a way to increase pollination of muskmelon and squash. A strip of perennial flowers are planted to attract pollinators to the plot.



10. EarthKind Rose Trial. EarthKind is an innovative new program that addresses environmental landscape management. We will discuss the northern EarthKind rose trial planted at the Horticulture Research Farm as well as the newly established EarthKind Hydrangea trial. These two plantings are part of the nationwide trialing program of rose and hydrangea cultivars being evaluated for their suitability for inclusion in EarthKind landscapes


The student organic farm ...

11. Turf Demonstrations
    • Lawn mower safety, maintenance, and selection.
    • A walking tour to identify weeds, insects, diseases, and their control.
    • Turf research plot tour.

Golf Course Management in Italy

I recently took a student group to Italy for a study abroad trip. Here is a picture of San Domenico Golf Course in far southern Italy in the province of Puglia (the heel of the boot). The club president came out to talk with us and the first thing he said was that their biggest problem is Poa annua. He wanted to know if there was anything new from the United States that would get rid of it.

It is interesting that there seems to be the same problems wherever you go.