Custom Search

Stormy skies

The major news around here this week has been the weather. No, that's not a photo of the Mother Ship come to take me home, that's the back of one of the many storm fronts that passed through this past week.

I'm sure you have all heard about the devastating tornado in Joplin. Other communities in the region were also struck.

Along with the violent winds, hail, etc, abundant rain has accompanied some of the storms. The University of Arkansas talks about wet conditions in their area. They also shared some images of flooding from some storms a few weeks back.

Here are some examples of how dark the sky got on Monday here in Manhattan. The clouds were so dark (at 10:00 am) that streetlights and car headlights were coming on:

Large patch

I was out and about earlier this week and saw some large patch symptoms:

At this site, the symptoms were a lot less common than they were in 2010. 2010 was extremely wet, and I think that's a big factor. After this week's cool, rainy weather, I expect to see a rise in symptoms.

Wet conditions also prohibited mowing, leaving a purple haze of several days of zoysia flowering heads:

In the dicot world: (oops, I mean non-turf world)

Those of you who deal with ornamental plantings might be interested in these observations about freeze damage in peonies and iris from a cold snap a couple of weeks ago. The pics and commentary are from one of my colleagues in the Kansas City area:

Spring dead spot of zoysiagrass

Spring dead spot of bermudagrass
After a cold winter throughout much of the Southeast, damage from spring dead spot is particularly severe on bermudagrass. Scenes like this one are all too common when visiting golf courses in North Carolina right now.

We're also seeing an unusually high number of spring dead spot outbreaks on zoysiagrasses across the southeastern US. Samples, photos, and reports of spring dead spot on zoysiagrass fairways, tees, lawns, and landscapes have been rolling in all spring.

Spring dead spot of zoysiagrass?

Yes, this is not a new thing. Spring dead spot was first documented in zoysiagrass by Green et al. in 1993 as part of the zoysia patch complex, which turned out to be mostly large patch and a little bit of spring dead spot. The Color Atlas of Turfgrass Diseases by Tani and Beard also lists spring dead spot as a disease of zoysiagrasses in Japan. 

In North Carolina, we've seen spring dead spot on zoysiagrass every year since 2002 and documented that it is caused by Ophiosphaerella korrae, the same species that infects bermudagrass in this part of the country.

Spring dead spot of 'El Toro' zoysiagrass
Overall, zoysiagrass seems to be more resistant or tolerant to spring dead spot compared to bermudagrass. The patches are typically smaller and not as widespread. Given the superior cold tolerance of zoysiagrass, this makes sense. The problem is that zoysiagrass is even slower to recover from spring dead spot than bermudagrass. Although the symptoms may not be as severe, they can linger for extended periods of time.

Not all zoysiagrass varieties seem to be susceptible to spring dead spot. In Kansas the disease was observed on 'Meyer'. In North Carolina, most cases have been observed on Zoysia japonica varieties like 'El Toro' and 'Empire'. 

Spring dead spot of 'Diamond' zoysiagrass
This year is a little different in that we're seeing spring dead spot on more varieties. Most notably, we've confirmed the disease on golf course fairways and tees established with the Zoysia matrella cultivar 'Diamond'. To our knowledge this is the first confirmation of spring dead spot occurring on Zoyisa matrella.

Spring dead spot management on zoysiagrass is identical to that on bermudagrass. We've seen very good results from preventive application of fenarimol (Rubigan) in the fall. Regular cultivation during the summer also helps to reduce spring dead spot development and speeds up the recovery process. We're continuing to research the effects of nitrogen sources and other fertilization practices on spring dead spot development, but I don't have time to open that can of worms this week. Stay tuned for details on that in next week's post!

Poa seedheads, basidiomycetes, and the usual suspects

With the recent spell of "warm" weather in combination with relatively high humidity, there were outbreaks of diseases we may typically see in June or even July. I reported a couple of weeks ago that things seemed to be picking up fast on the disease front. However, things seem to have slowed down least for the time being.

A quick walk around Valentine (Penn State's Turf Research Facility) was met with the usual suspects at this time of the year. We are seeing red thread and some leaf spot in the roughs, brown ring patch on the Poa putting greens, and today I saw what I believe to be superficial fairy ring (below). We are planning on isolating this one and hope to compare it to what we found over the last few weeks and what I have been calling Thatch Collapse (right). The SFR is showing up in my fertility plots, so it will be interesting to see if there is a difference based on N-source.

Other than that, Poa seedheads are in full force and we are seeing good control in select treatments. I hope to talk about this in the next few weeks once I get the data analyzed, but tentatively it looks like we are seeing good control with a few products and our application timings did make a difference in the level of control.

Why They Call it the Transition Zone

Spring dead spot of bermudagrass

As the old joke goes, "In the transition zone, we can grow all of the turfgrasses, we just can't grow any of them well".

The last year has been an excellent demonstration of this fact. Spring 2010 brought major problems with winter-kill in the warm-season grasses across much of the southeast. Everyone will remember the summer of 2010 as the year when record heat caused widespread failure of creeping bentgrass putting greens. 

Large patch of bermudagrass
The spring of 2011 hasn't been much kinder. Spring dead spot is particularly severe on bermudagrass this spring, and I've heard several reports of control failures from preventive fungicide applications. We've seen an unusual number of cases of spring dead spot on zoysiagrass as well (more on that next week).

Large patch (aka zoysia patch, aka brown patch, aka large brown patch....did I miss any? Seriously, can't we all just call it large patch?) is raging on all of the warm-season grasses as well. This spring is the first time I've seen large patch cause significant damage to bermudagrass in the Raleigh area. Zoysiagrass, St. Augustinegrass, and centipedegrass are affected very severely as well.

Many people struggle with these diseases of warm-season grasses because they have to be treated long before the symptoms express themselves. It is easy to forget about spring dead spot and large patch in the fall when everything is looking good. 

In addition, the economic downturn has led to severe budget cuts at many facilities, and the poor warm-season grasses are usually the ones that are left to fend for themselves without fungicide protection.

Over the next few weeks, I'll be writing in more detail about spring dead spot and large patch in the warm-season grasses. We'll cover things you can do now and during the growing season to help manage these diseases and how to prepare for preventive fungicide applications this fall. Stay tuned!

Large Patch Resistance of Zoysia?

Last year I suggested that there are differences in large patch susceptibility between Zoysia japonica and Zoysia matrella. A photo of large patch posted last month on the Turf Diseases Facebook page by Dr. Mike Richardson and follow up comments by Dr. Richardson and Dr. Kennelly on the relative lack of resistance they have observed has prompted me to write on this subject again, for all of my observations lead me to believe that there are differences in susceptibility to large patch among zoysia varieties and between zoysia species. Click on the thumbnail images to see photos of large patch on zoysia in Asia, and you will see that the symptoms are most evident on Zoysia japonica:

large patch on Zoysia japonica large_patch_noshiba_kanagawalarge_patch_noshiba_west_japan large patch on zoysia at Shimane, West Japan

Why am I convinced that there is some resistance to this disease?
  • I've noticed that when Zoysia japonica and Zoysia matrella are growing in the same general vicinity, large patch may be present on Zoysia japonica but not on the Zoysia matrella.
  • Research at the Chiba Prefectural Agricultural Experiment Station in Japan has found that there are differences in resistance to large patch among zoysia varieties.
  • Dr. Larry Stowell suggested there may be a mowing height effect on the disease where higher cut turf might be more susceptible but a greenkeeper at Japan assures me that at his course it is the Zoysia japonica at fairway height that gets more disease than the higher mown rough.
  • Masahiro Kato has published on large patch resistance in zoysia and he found that the differences in resistance among varieties are related to differences in leaf sheath lamination structure.

Things are picking up FAST!

Yesterday (this was meant for yesterday, but new disease activity today [Tuesday] has me posting a day late) I had the pleasure of hanging out at the Rutger's Annual Golf Classic which raises funds for their research program. I even got to play a little golf with our Midwest blogger Jim Kerns. Having left State College on Sunday and not really seeing much of anything on the disease front at Penn State, I was excited to find out if there were any actual turf diseases in the field...we hit the jackpot in North Jersey.

While certain diseases like anthracnose, leaf spot and brown ring patch were very active, I was surprised to see active dollar spot and RECOVERING brown patch (looked like it was active about a week ago or so). I think that things have been some moist and humid that everything is just taking off at this point. This would definitely be the earliest I have ever seen brown patch in the mid-Atlantic region and is in general pretty early for dollar spot as well.

Thatch collapse
This morning I headed into the Valentine research facility in State College and was surprised to see a LOT of disease activity there as well. We still don't have any dollar spot and brown patch is definitely a ways off for us, but there are several things going on. First, seedheads are in full force right now and we will be rating our plots over the next few weeks to see what worked and at what timing. As for diseases we are seeing: red thread, leaf spot, brown ring patch (images below, we are confirming by isolation...update to come), thatch collapse (see next month's GCM issue), Microdochium patch, and probably something else that I am forgetting.

So diseases are here or just around the corner...we could be in for another long year.
Related Posts with Thumbnails