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:

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.

Top Five Diseases of Warm Season Turf at the 2011 GCSAA Education Conference

What's the Biggest Problem for Warm Season Turf?


Dr. Phil talkin' about Diseases on Monday

Last Monday, Phil Harmon, Megan and I got to teach the Management of Diseases of Warm Season Turfgrasses here in Orlando.

It was out third time doing it together and I think each time we’re getting better. I think Bruce Martin from Clemson has stopped checking up on us to make sure that we’re doing the class right, which is good, but we sure do miss the opportunity to put Bruce on the spot! Bruce taught the class previously for >10 years at GCSAA, and it took three of us to replace one of him!

This year we had about 45 students with Florida heavily represented in the group. We had some visitors from Central America and as far away as Australia, but most of the guys came to talk about bermudagrass and bermudagrass diseases in the southeastern U.S.

A survey taken during the class showed the disease issues that superintendents are most concerned with for warm season turf (by # of mentions):
1. Fairy Ring (22)
2. Rhizoctonia zeae aka mini-ring (18)
3. Large Patch (15)
4. Gaeumannomyces Decline (11)
5. Bipolaris Leaf Spot/Melting out (7)

Surprised?

We’ll follow up in the next few weeks on these diseases and what’s the best management strategies for each of them.

Until next week, signing off from the right coast....

Fungicide Review: Polyoxin D

Polyoxin-D: Mother Nature’s gift for fighting Rhizoctonias (and some other important diseases).

Polyoxin-D zinc salt is the active ingredient in two turfgrass fungicides: Endorse (Arysta) and Affirm (Cleary Chemical). There’s been some switching around of names and products since 2009 (as discussed last year) when Arysta LifeScience took back the distribution rights for the 2.5% WP formulation and Cleary’s introduced Affirm, a 11.3% WDG formulation, that contained the same active ingredient. Either way, both formulations have the same range of disease control and I haven’t seen any data so far to suggest that the two formulations have any significant differences in disease control between them. Polyoxin D is classified as a FRAC Group 19 fungicide (polyoxin antibiotics) and presently, only polyoxin D is registered as a turf fungicide in the U.S. (Image to the right taken from alanwood.net)

There are a number of other polyoxins out there (polyoxin A, polyoxin B,…polyoxin J, etc.), and they all share a common “ancestry” as far as being discovered as metabolites of Streptomyces bacteria (which are commonly called Actinomycetes). Streptomyces are typically soil inhabiting bacteria and are potent producers of some very important anti-bacterial and anti-fungal antibiotics. Interestingly, antibiotics derived from Streptomyces species account for two-thirds of our commercially available antibiotics including streptomycin, chloramphenicol, tetracycline and vancomycin (anti-bacterials) and nystatin and amphotericin B (anti-fungals).

Polyoxin D was discovered in 1965 as a fermentation product of Streptomyces cacoi var. asoensis (Suzuki et al 1965 Journal of Antibiotics Ser. A), so interestingly, this molecule has been around for a long time! Commercial fungicides containing polyoxin D utilize this active ingredient in the form of a zinc salt. Why, may you ask? Because the polyoxin D molecule is extremely water soluble and it would wash off of plant surfaces easily; the zinc salt form of polyoxin D is much more stable and enhances the longevity of the fungicide on the plant surface.

Biochemically, polyoxin D inhibits the formation of chitin, which is the main component of the cell walls of true fungi (Ascomycetes, Basidiomycetes, etc.). You can see from the photo here (taken from Endo et al. Journal of Bacteriology 1970), that fungal cells treated with polyoxin D (top photo) are unable to make functional cell walls and thus can’t function normally like the untreated ones (bottom photo).

Since Oomycetes like Pythium don’t use chitin in their cell walls, polyoxin D won’t affect these “water mold” type fungi. Polyoxin D is considered a local penetrant fungicide, and does not translocate easily upwards in plants like some other systemic fungicides, so coverage is important when applying these.

The earliest use of polyoxin D was for the control of rice sheath blight (Rhizoctonia solani) in Japan back in the 1970s. Not surprisingly, for turf diseases, Endorse and Affirm would be considered strongest against Rhizoctonia diseases like brown patch, large patch and yellow patch and the Rhizoctonia-like Waitea diseases like brown ring patch and leaf and sheath spot.

In a large patch trial we did in 2008, you can see that Endorse was very good in controlling large patch.

Applications made 16 Apr and 6 May to bermudagrass

In a brown ring patch trial also conducted in 2008, Endorse provided some of the quickest control of the disease, but didn’t have as much residual as some other treatments. We suggest tank mixing Endorse or Affirm with another fungicide like a DMI (Banner MAXX, Tourney, Triton or Torque) to get good knock down and added residual.

One curative application made on 26 Apr

In our California trials, we’ve seen it been pretty good against anthracnose and although other materials seemed to be better, Endorse and Affirm could certainly be added into the summer rotation.

Six applications total from Jun to Aug, 2005 data

Other diseases on the labels include pink and gray snow molds (it seems like they are best tank mixed with another fungicide for the best control, but ask Jim about that one), red thread, leaf spots, gray leaf spot, and fairy ring.

Endorse looked pretty good vs. fairy ring in trials conducted by myself and Mike Fidanza :www.gcsaa.org/gcm/2007/may/pdfs/treatingFR.pdf

However, I can’t say that I’d recommend polyoxin D by itself for gray leaf spot, I just haven’t seen enough data to say it’s a good choice for this disease when other fungicides are available.

OK – that’s enough geeking out for tonight – until next week, signing off from the Right Coast….

What is the Most Interesting Disease in the World?

I think of two diseases that, at least by name, are the most interesting in the world. Surely there are others. I'd like to hear them. Fairy ring must have some poetic names in various languages? But I still think it is difficult to beat zō no ashiato. Check out this adventure story to find out why.

and here is the exciting conclusion!

NO WIND = DEAD GRASS

I'm back.

For those of you who were hoping that my first post would be on bacterial wilt, I am sorry to disappoint you, but we have more important problems here in the Southeast right now.

Several years ago, I got a call from an angry homeowner who lived in a golf course community. The golf course superintendent had installed a fan adjacent to the green in her back yard. Said fan was preventing her from enjoying her patio, keeping her awake at night, and reducing the value of her property.

She must have been a scientist of some sort, because she asked me if I had a mathematical model that could be used to determine if a fan was necessary. So I broke out my plant physiology, meteorology, and calculus books and after several weeks of analysis, I came up with the following equation:

NO WIND + HEAT = DEAD GRASS

I don't think she liked that answer because I never heard from her again. But this summer is proving my equation to be correct: I have never seen fans make such a huge difference in the survival of creeping bentgrass putting greens as they are this year. Just about everywhere I've visited, the creeping bentgrass being impacted by fans is relatively healthy, whereas the turf furthest away from the fans or on greens without fans is really struggling.

It's been a difficult summer and there's no sign of it getting any easier. But if one positive thing can come out of it, we can use it to demonstrate the benefit of turf fans, fine tune the placement of existing fans, or fight for the money to install additional fans. Don't miss this opportunity!

On the disease side, a number of superintendents in our area are still struggling with Pythium root rot, and some summer patch is also showing up on creeping bentgrass greens. For more information about these diseases, please see the following post from last year.

We have also seen a couple of cases of Rhizoctonia zeae on creeping bentgrass greens. This pathogen induces similar symptoms to brown patch, but is active at higher temperatures and the patches or rings have more of an orange coloration. Most fungicides labeled for brown patch will provide good control of R. zeae, but this pathogen is not sensitive to thiophanate-methyl and is less sensitive to iprodione so you should avoid these products.

Blue Skies, Nothing But Blue Skies...

The last post focused on my final thoughts on snow mold and since then the weather in the Upper Midwest has been great! We have had a very early spring. This is good for the golf industry because golfers have been able to play golf! The last couple of weekends have not been nice, but at least some weekday play is occurring. The TDL, my phone and email have been fairly quiet with respect to turfgrass problems. We have been very dry the last month or so and this week has been extremely windy. When I was still at NCSU, Lane used to make a very simple point to his students-What is most important to a fungus? WATER! We haven't seen or heard of a lot leaf spot development because of the dry spring. The only interesting symptoms we have seen are some unusual reddish brown rings on one of our putting greens at the OJ Noer. Upon incubation of the affected turf, we obtained a Rhizoctonia like fungus. The cultures are only a few days old, so I don't know what fungus it is yet. The reddish brown rings were a little unusual though.

Besides the development of this little anomaly, we have been busy laying out our summer fungicide trials. We have also been busy planning our summer field day, which is scheduled for July 27th. We are changing the format slightly this and we are still planning on conducting the afternoon Lawn Care Session that focuses on basic turfgrass management skills. The topics include, grass ID, weed ID, sprayer and spreader calibration and pest identification. We are kicking around having a congruent session that focuses on advanced turfgrass management skills, like soil moisture measurement and interpretation, disease diagnosis and fungicide program development and insect management. If you think this would interest you please let me know!

I think this summer will present some interesting challenges as most summers do. We also have a whole lot going on so stay tuned! Next week I will be in Lane's state for a much needed beach vacation, maybe I'll report on the turf I see there :). Before I go the picture attached to the post is a representation of one of my most favorite cities! We were out on the lake during mid-April!

Coolest July on Record!

Well the big news from the Midwest is we just experienced the coolest July on record! I guess you can imagine that there is not a lot of disease activity. Dollar spot is progressing, but very slowly. Even at one particular site in Milwaukee that is usually a petri plate for dollar spot, the disease has been very slow to develop.

We have had some brown ring patch come through the lab recently and most people in the Midwest are able to clean that disease up with an application of Endorse or Prostar. Dr. Frank Wong has also shown that applications of nitrogen fertilizers also help to alleviate brown ring patch symptoms.

This post will be a little short because I have just returned from Portland where I attended the American Phytopathological Society meetings. Another fantastic meeting! I will let Frank elaborate on the fun sites :)! There were some excellent talks and posters. One talk I thoroughly enjoyed was by Steve Kammerer who is at the University of Florida. I know we do not grow warm-season grasses, but nonetheless Steve and Dr. Phil Harmon may be instramental in renaming or changing Rhizoctonia classification. Great job guys. For those growing warm-season grasses and are struggling with something a little weird, you might want to get in touch with Dr. Harmon or Steve.

One final note, this weekend is projected to be quite warm in the Midwest, so if you have not sprayed for dollar spot in a while tomorrow or Friday may be a good time.

Don't neglect your nozzles!

As your college interns start to filter to the course from academic studies, now is the perfect time to fire up the sprayer in preparation for the 2009 season. This gives you the opportunity to ensure that your equipment is in proper working order AND gives the students the opportunity to get hands-on experience with calibration techniques that many have only heard about in the classroom.

Many websites and books are available to assist in the calibration of your equipment. In preparing for this update, I also came across a calibration software package that TORO offers for download from their website. While calibration of your equipment is important, another factor that should not be overlooked are the nozzles that you select to control turfgrass diseases.

Research conducted in the past few years has revealed that nozzle selection plays an important role in the suppression of turfgrass diseases (Read GCM Article). In particular, the control of foliar diseases such as dollar spot and brown patch can be improved by selecting nozzles that improve spray coverage. One major problem with this is that nozzles producing excellent coverage generally have increased potential for drift. Our research has shown that utilizing nozzles that incorporate air into the droplets (air induction) provide the best of both worlds. Here are some keys to improving disease control.

1. Consider the location of the pathogen. Fungicides for root diseases generally need to be applied in greater volumes of water (>2.0 gal/1000 sq ft) and/or watered-in following application. Foliar pathogens should be suppressed with a nozzle that produces excellent coverage.

2. Air induction nozzles provide excellent control of foliar pathogens and have relatively low potential for drift. TurfJet nozzles (typically supplied with many sprayers) generally offer poor disease control, especially where lower water volumes (~1.0 gal/1000 sq ft) are utilized.

3. Nozzles should be changed at least once per year (twice per year in some cases). Always buy an extra nozzle to use as a comparison when determining if your nozzles need to be replaced.

Brown Ring Patch or Yellow Patch?

Disease activity is relatively slow at this point, but there are some reasons to believe that this will change soon. So far, several cases of brown ring patch and yellow patch (i.e., cool temperature brown patch) have been identified from Pennsylvania to parts of New England. A quick way to distinguish between these two diseases is to incubate a cup-cutter plug in a tuperware container overnight. If mycelium is present in the morning, you are likely dealing with brown ring patch as yellow patch does not produce much visible mycelium.

Main areas of interest throughout the region have focused on annual bluegrass seedhead suppression and the application of early season fungicides for the control of dollar spot or fairy ring. In situations where chronic disease activity occurs, these early season fungicide applications have been shown to reduce the severity of each disease later in the year.

If you are in the Northeast and experiencing other disease problems, feel free to let us know in the comments section.

patch-a-rama in Kansas

Hello from Kansas

The warm-season grasses are greening up. Spring rains and temps in the 60's and 70's are triggering the development of large patch in zoysiagrass (see photo). I have not seen or heard of symptoms of spring dead spot yet in bermudagrass but I'm sure that will be coming soon.

As for the cool-season grasses, a superintendent in south central KS reported some yellow patch (cool-season brown patch) in the putting greens. Late April is fairly late, but with our unusually cool, wet weather I'm not surprised that this disease has popped up. Another person reported some powdery mildew on tall fescue in the Kansas City area.