Make your Friday night Reserve-ations

Book 7, part I … are you kids as excited as I am?

Maybe some of you went to the midnight showing last night?

My main post is about Reserve, but at the bottom I have some follow-up comments about granulars.

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RESERVE

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Last week I accidentally gave away a little bit of my story prematurely. Maybe it was my headachy/sleepy day, but I thought my fungicide assignment was Renown, not Reserve, and shared a little bit about a 2010 that included Reserve. You can look back at my post last week where Reserve was one component to a couple of program trials.

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What is Reserve? It’s a new formulation from Bayer that combines triticonazole (0.54 pounds active ingredient/gallon) and chlorothalonil (4.25 pounds a.i./gal) as well as StressGuard.

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It is labeled for quite a few diseases: anthracnose, brown patch, microdochium patch/pink snow mold, typhula snow mold, necrotic ring spot, red thread, rust, summer patch, take-all, large patch, and dollar spot as well as algae and summer decline.

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Like other triticonazole products, there is potential for damage to bermudagrass. The label indicates that it should not be used at all on ultradwarf bermudagrass varieties. In addition, the label says not to exceed 5.4 fl oz/1000 every 30 days on any type of bermudagrass, and, for golf courses in Florida, do not apply Reserve to bermudagrass greens when temperatures exceed 90. Lane talked about this topic awhile back, and you can read about it here:

http://turfdiseases.blogspot.com/2009/10/effects-of-dmi-fungicides-on.html

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How has Reserve performed in KSU trials? As I said, it worked well as part of the program trials this year, and you can see last week’s post.

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In 2010, we also compared Reserve with Concert, which is a formulated combination of propiconazole (0.3 pounds a.i./gal) and chlorothalonil (4.0 pounds a.i./gal).

Concert: applied at 5.5 fl oz/1000

= 5.9 grams propiconazole + 78 grams chlorothalonil/1000 ft2

Reserve: 2.5 fl oz/1000 = 4.8 g triticonazole + 37.7 g chlorothalonil/1000

______3.2 fl oz /100 = 6.1 g triticonazole + 48.2 g chlorothalonil/1000

______3.5 fl oz/1000 = 6.7 g triticonazole + 52.8 g chlorothalonil/1000

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The 2.5 fl oz rate of Reserve was applied 7 times, on 24 May, 9 June, 22 June, 28 June, 6 July, 14 July, and 20 July. The other treatments were applied 5 times, on 24 May, 9 Jun, 22 June, 28 June, and 14 July.

Disease in the untreated plots bounced around a little bit, peaking twice at around 9% severity. Except for a little bit of breakthrough (2%) in the lowest rate of Reserve, all the treatments held disease around zero (click to enlarge).

As you might expect, the repeated applications of the propiconazole-containing Concert did have some negative DMI-type growth-regulating effects that reduced quality. However, keep in mind that most people would be rotating, not applying the same product over and over. This is an artificial type of situation used in an experiment.

Here are two pics, one with plot borders shown and one without, showing the quality effects associated with the repeated applications of the propiconazole-containing product. The triticonazole-containing Reserve did not have such effects.

Results were pretty similar in a trial I conducted in 2009.

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Color splash or color crash? It’s not easy being blue-green?

I do have a final question about the StressGuard… I have heard from a couple of superintendents (like, literally, TWO) who don’t like the strong color that is apparent immediately after application. One guy said that he avoids products for that reason, and another said that he’ll water the products in a little bit to wash of the color. Anybody else have comments?

GRANULARS

I have a few comments related to Lane’s posting about granular formulations. I have a few observations for formulations of azoxystrobin.

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In 2008 I ran two trials for brown patch in tall fescue (lawn-height). In one trial, the applications were done on July 9 and August 5. The trial included Heritage TL at 2.0 fl oz/1000 (5.7 grams a.i./1000) and Heritage 50 WG at 0.4 oz/1000 (5.7 grams a.i./1000). On the morning of August 5, I rated the % blighting per plot before the treatments were applied. Disease in the untreated was at 32.5%. Here's a photo to show some symptoms:

Whereas both Heritage formulations knocked disease down to 0%, like in the plot below.

In a separate trial nearby, I applied Heritage G at either 2 or 4 pounds/1000, equivalent to 2.8 or 5.6 grams a.i./1000. Applications were done on June 30 and July 28, and disease was rated on August 5 (same as the other trial). In this one, the untreated was similar to the other trial, with about 40% blighting. The Heritage G treatments reduced disease to 7.5% (2 pound rate) and 4.5% (4 pound rate). So, while they did significantly reduce disease, it was not down to 0%. This photo shows some breakthrough with a granular treatment (blighted areas circled):

Of course, these trials were not set up to directly compare the granular with the sprayables, but it is consistent with Lane’s comments (and others) that granulars can lack the consistency that you might find with a sprayable formulation.

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New Granular Fungicides for Turf

Historically, fungicides on granular formulations have never been used frequently on turf. With the exception of late fall snow mold applications and damping off applications to the seedbed, there weren't many situations in which granular fungicides were recommended.

Two things were limiting the usefulness of granular fungicides: a limited selection of products and low-tech carriers that weren't very effective for foliar disease control. As a result, my standard recommendation has always been that if you want good disease control,  you should spray instead of spread. As an example, look at the tall fescue plots to the left that were both treated with triadimefon at the same rate of active ingredient per acre. Triadimefon is not a very effective brown patch fungicide to begin with, but the sprayable formulation (Bayleton) is much more effective that the granular formulation (Fungicide VII).

Things changed quickly, though, and today many more products are available on granular carriers, including recent products like Armada, Disarm, Heritage, and Headway. Several others are currently being tested as experimentals. Furthermore, these new products take advantage of modern granular formulation technology that makes them more effective against foliar diseases by increasing foliar absorption of the active ingredient.

We've evaluated a number of these new granular formulations, mostly against brown patch in tall fescue in a lawn care scenario. I will include a couple of examples here. I would summarize by saying this: these new granulars are more similar to their sprayable counterparts for brown patch control, but generally their efficacy is a erratic and they require more frequent applications. I still think that if you have the capability to spray, it's still better to spray. But these products provide more options to turf managers in situations where spray applications are not possible or practical.

Another possible advantage of a granular formulation is for control of root diseases like summer patch, spring dead spot, fairy ring, take-all patch, etc. To control these diseases most effectively, you obviously want the active ingredient to be in the root zone. With a granular, you can make the application and then water in later at your convenience, rather than having to worry about running the heads right behind the sprayer before it dries on the foliage. While we haven't tested these newer products against root diseases, we always used to see very effective spring dead spot control from granular formulations of Rubigan.

I'd like to hear some comments from our readers on this topic: What are the advantages and disadvantages of these granular formulations in your experience? If you are using these products, how and for what are you using them?