Sun, Ice, and Climatological Normals

Since my last post I've been to England and the UAE, Philippines, Vietnam, Thailand, and Japan. I've seen most grass types but not many diseases; a bit of fairy ring, some dollar spot, slime mold, and Curvularia. What I have seen is a lot of variability in the weather, and especially in Asia I have seen the typical cloud cover, rain, and associated low sunshine hours that are so widespread during these months of the year.

When we look at the factors that influence turfgrass growth, we can identify nutrient status, water status, temperature, and light as being the primary factors. But with drainage, supplemental irrigation, and fertilization, turfgrass managers are able to control the nutrient and water factors, at least in theory, which leaves just temperature and light as the factors influencing growth. I find it useful to look at the climatological normal data, as seen in the chart below for August, or in this interactive chart with data for the entire year, to evaluate how the temperature and sunlight may influence turfgrass growth at a particular location.

Zoysiagrass outperforms seashore paspalum and bermudagrass in low-light conditions, both in the research setting and in the field throughout Asia. In tropical Southeast Asia, where the temperature remains relatively constant throughout the year at an optimum level for warm-season turfgrass growth, it is the light factor that controls the growth of the grass. Zoysia is especially well-suited to that environment.

An environment that creeping bentgrass is not well-suited to is the summer in Japan; a place like Osaka (where bentgrass is almost universally used on putting greens) is hotter during August than cities such as Singapore, Honolulu, and New Orleans. I've been making some measurements of the changes that take place in surface temperature and soil temperature when ice or ice water are applied to creeping bentgrass greens in Japan. I've been surprised at the persistence in soil cooling from the melted ice, although clouds and rain have moved in this week and I've been unable to continue these experiments.

Is it Starting to Feel Like Groundhog Day?

So I bet many of you in the south are feeling like Bill Murray in the 1993 movie “Groundhog Day”. I know I am. Everyday we look at turfgrass samples with the same problem. Heat-related stress and decline and severe nematode populations! Many superintendents that I have spoken to are getting as frustrated as me. This heat is getting old. We are now sitting at 45 days above 100F here in Stillwater. In the Oklahoma City area they are knocking on the all-time record of 50 days! Everyday the same thing…

The OSU Turfgrass Diagnostic Laboratory has churned through a bunch of creeping bentgrass putting green samples in the last couple of weeks. The large bulk of samples have extremely short root systems. The heat has really taken its toll on creeping bentgrass in much of the south central U.S. Throw in some nematodes damaging what roots are left and we have a lot of turfgrass in serious decline. Very high populations of stunt (Tylenchorhynchus spp.) and ring (Criconemella ornata) nematodes have been observed in many of the samples submitted. We have seen populations of stunt nematodes as high as 4,000 individuals in 100 cc of soil. This is about 26 times the threshold we consider the “danger zone” on creeping bentgrass. Ring nematode populations have been coming in as high as 2,000 individuals per 100 cc soil, which is about four times the “danger zone” population level. So as you can see, things are getting tough here at the end of the summer in the south. Many are praying for cooler weather and rain. Although, those that have gotten rain have been struggling with wet greens and hot weather, which makes for a whole different set of hurdles.

Other issues in the diagnostic lab have been few and far between, but we did have one sample with Pythium root rot. This was an odd situation where the greens got dry and severe wilt began. To compensate the newly hired assistant superintendent turned the irrigation system on and severely over-irrigated multiple times. When you have lots of soil moisture and high temperatures in the rooting zone, Pythium root rot can help finish off the already declining plants. So while, not the initial cause of the problem, we did identify something other than nematodes. In our research plots, brown patch has also been active and dollar spot comes and goes pretty much as the humid weather comes and goes.

The long-term forecast is showing cooler temperatures, if we can just get through this weekend. As Dr. Kaminski has said in a previous post “there is light at the end of the tunnel.” So keep your head up and your fingers crossed for cooler temperatures, I think we will be there soon!

Greetings from Canada

Hello there! My name is Katerina Jordan and I am a turfgrass scientist at the University of Guelph in Ontario. I was asked to be a part of this blog and am posting a brief introduction for those of you who don’t know me.

Most of Canada has a much shorter season than in the States, but our superintendents are no strangers to a wide variety of diseases on their turf. This season has been a tough one for managers here in Ontario as we experienced a cool, wet spring followed by some of the hottest temperatures on record combined with prolonged periods of drought. Many turfgrass managers in the U.S. are used to excess heat and drought, but for most of Canada this kind of summer is very foreign to us. On the up side, the lack of moisture has kept a number of diseases at bay, but the turf (epecially the Poa annua) is suffering quite a bit from the prolonged stress. Fortunately, we are headed into the end of our summer as temperatures start to drop significantly by mid-August.

Major issues that we deal with here are dollar spot and anthracnose throughout the country, take-all patch and summer patch in Ontario as well as some of our prairie provinces (Alberta and Saskatchewan) due to very high soil pH levels, and plant-parasitic nematodes in British Columbia, the eastern provinces and here in Ontario. However, the diseases that we deal with the most in the colder provinces are the snow molds – both gray and pink.

I look forward to updating readers to goings on here in Canada based on discussions with superintendents and from the samples we receive in our diagnostic lab.

Good luck with the rest of the season!

A plant pathologist's dream come true - patch-a-rama

Hello out there,

I don't have too much to report, but we are having an impressive outbreak of brown patch this week at our research facility. I wanted to get a lawn chair and just sit out there on the research green and take it all in. Here are some images, smoke-rings included.

With moss:

With dollar spot:

With scalping injury:

The temperatures have dropped, with highs in the coming days in the 90's and even some 80's in most of Kansas. In southern Kansas it looks like there will be a few more days of ~100 then some 90's and 80's. Poor Oklahoma still looks super hot, though. Ugh.

Some parts of Kansas also got some rain yesterday and today, but many areas missed out. Our KSU turf field day got rained on yesterday in the Kansas City area.

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Light at the end of the tunnel (e.g., It's August)

It's been a busy week for golf course superintendents in the region as diseases are in high gear and the heat and temperature stress are causing many golf course putting greens to decline. We are hearing a lot of reports of yellowing and discoloration to bentgrass putting greens, possible nematode issues, and the typical diseases that we would expect to see at this time of the year.

Rain storms that swept through much of the mid-Atlantic provided some much needed relief from the drought we were in, but in many cases the rain fell too fast and basically moved via the surface. The good news from that was that many of you who had ponds that were getting low got a "refill". The bad news is that this did little for replenishing the soil and also washed out a few hundred bunkers. There were even reports in parts of southeast PA of flooding due to the massive storm that came through last week. On the other hand, there were also courses that DID manage to get the slow and steady rain that helped to wet the soil. Following these rains, dollar spot became VERY active and anyone not covered with fungicides saw cotton candy fairways on Tuesday.

Heat stress continues to be the biggest issue throughout much of the region and I can't stress enough that just because the turf is declining doesn't mean that it is pathogen related. In many cases, the soil temps are just too high and/or the growing environments too poor. As we hit the home stretch of summer, it is important to continue to be diligent on your water management. Yes, I know that it is not practical for many of you to get out there and hand-water everything as the courses with a $2,000,000 budget do, but the bottom line is that if you are using your overhead irrigation to "syringe" then you are probably over watering (this was from a USGA agronomist who I believe it going to write an article about it for an upcoming issue of the USGA Record).

Active right now: dollar spot, brown patch, Pythium blight, anthracnose, fairy ring, summer patch, others?

Website update: We are in the process of finalizing the details/construction of the new website for Turf Diseases. Some planned features include:

• More authors for more updates
• Restructuring of regional updates in line with USGA Regions
• New "Research" section for the latest research updates from the scientists
• New "Tech" section (you'll have to wait for the launch to find out more)
• Disease profiles and Image galleries
• Disease updates from superintendents