# Please critique my fungicide plan



## DFW St Aug (10 mo ago)

I have owned my current property for nearly 7 years, and the only fungicides I have used up until last season were Azoxystrobin and Propiconazole. Last season, I had gray leaf spot pretty bad in several sections of the yard, and ended up putting down Thiophanate-methyl which worked fairly well, but I still had a few problem areas.

I had planned to try and use mostly granular products this year, but obviously they are more expensive. I have a bag of Pillar G that I am going to put down this weekend, and then I am going to get a good powered sprayer and start using liquids.

My plan after the Pillar G is to alternate between Azoxystrobin and Chlorothalonil for 4 weeks and then Myclobutanil and Thiophanate-methyl for 4 weeks. Does this seem like a reasonable preventive plan? If I had issues later in the season, I would add to it.


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## CenlaLowell (Apr 21, 2017)

Good luck I caught hell with fungus in my st Augustine. My suggestion would be to make sure you fix your soil starting with a soil test.


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## DFW St Aug (10 mo ago)

Would you recommend any changes to the preventative plan I have going into this season?


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## david_ (Aug 22, 2019)

Are you addressing the root cause? Overwatering? Evening watering? Shade?


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## DFW St Aug (10 mo ago)

david_ said:


> Are you addressing the root cause? Overwatering? Evening watering? Shade?


Watering was fine, some of the areas are more shaded but it can't be avoided. Do you think this is a good preventative plan to start the season?


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## david_ (Aug 22, 2019)

I do, but I'm not an expert as I typically throw down some disease ex when my palmetto inevitably turns to $hit mid-summer.

LCN has good St. Aug fungicide videos - i.e. https://www.youtube.com/watch?v=JAXNDXAwp0w&ab_channel=TheLawnCareNut


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## CenlaLowell (Apr 21, 2017)

DFW St Aug said:


> Would you recommend any changes to the preventative plan I have going into this season?


Nah,. Your using good products already. I've dealt with this and it's not the products your using I can promise you.


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## DFW St Aug (10 mo ago)

CenlaLowell said:


> DFW St Aug said:
> 
> 
> > Would you recommend any changes to the preventative plan I have going into this season?
> ...


Every St. Augustine lawn in my neighborhood had a fungus problem last year. I'm just trying to stay ahead of it this year.


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## DFW St Aug (10 mo ago)

@david_ I have seen all of his videos on fungicides. Normally he suggests Azoxystrobin and Propiconazole together and last season when he had his own issue with gray leaf spot, mixed Thiophanate-methyl into the rotation. That is what I did last season, so I am looking for a slightly modified strategy going into this season.


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## Sling Blade (May 31, 2021)

Looks fine to me. I also have issues with gray leaf spot and rotate between all of the fungicides you listed. Going to try to get ahead of it this year and begin spraying at a preventative rate before it shows up. If you haven't already I'd take a look at this website to see the effectiveness of the different fungicides against what you're trying to prevent / cure.

https://www.turffiles.ncsu.edu/diseases-in-turf/


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## DFW St Aug (10 mo ago)

Sling Blade said:


> Looks fine to me. I also have issues with gray leaf spot and rotate between all of the fungicides you listed. Going to try to get ahead of it this year and begin spraying at a preventative rate before it shows up. If you haven't already I'd take a look at this website to see the effectiveness of the different fungicides against what you're trying to prevent / cure.
> 
> https://www.turffiles.ncsu.edu/diseases-in-turf/


Excellent, and thank you very much!


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## UltimateLawn (Sep 25, 2020)

@DFW St Aug , sounds like we have a lot in common. I am in DFW running with St Aug. I'm always battling fungus outbreaks depending upon the time of year. My challenge is I'm in full sun trying to keep the St Aug alive in the DFW heat without shade. I use a mix of Azoxy, Clearys and occasionally propiconazole.

Knowing which fungus you are fighting really helps. Last year there was a big TARR outbreak and the freeze helped contribute to a slower green-up when the TARR was hitting hard. I'm already seeing some yellowing that could be a TARR attack again.

I am getting pretty tired of paying high fungicide prices and having to do so many apps. At this point I am letting the St Aug die out as the bermuda takes it over. It seems that bermuda is much more resistant to all of these fungus problems. Where I have shade I'm building out gardening beds. Even if the St Aug can grow better in the shade, it is just too much trouble there as well.

I'll be following your thread to see where this discussion goes.


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## Austinite (Oct 4, 2018)

I spray and use granules monthly. Sometimes twice monthly depending on how varying weather can be that month. Same with Insecticide. So long as you are rotating (vital) you will be fine.


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## DFW St Aug (10 mo ago)

UltimateLawn said:


> @DFW St Aug , sounds like we have a lot in common. I am in DFW running with St Aug. I'm always battling fungus outbreaks depending upon the time of year. My challenge is I'm in full sun trying to keep the St Aug alive in the DFW heat without shade. I use a mix of Azoxy, Clearys and occasionally propiconazole.
> 
> Knowing which fungus you are fighting really helps. Last year there was a big TARR outbreak and the freeze helped contribute to a slower green-up when the TARR was hitting hard. I'm already seeing some yellowing that could be a TARR attack again.
> 
> ...


I have several areas of my yard that are full sun, but I've been able to keep the St. Augustine dominant there, although there is a small amount of Bermuda. It is definitely a high maintenance grass, but I like the look of it and enjoy working in the yard. Last year was definitely tough with the big freeze, and everything seemed behind. I'm more hopeful this year.

Those are the 3 active ingredients I have used, but I am trying to add other ingredients and MOA this season. Going all liquid is definitely going to save me a lot of money. I will be sure to keep this thread updated to see if this plan works.



Austinite said:


> I spray and use granules monthly. Sometimes twice monthly depending on how varying weather can be that month. Same with Insecticide. So long as you are rotating (vital) you will be fine.


What is in your fungicide rotation? Do you use 2 or more MOA per application?


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## Austinite (Oct 4, 2018)

DFW St Aug said:


> Austinite said:
> 
> 
> > I spray and use granules monthly. Sometimes twice monthly depending on how varying weather can be that month. Same with Insecticide. So long as you are rotating (vital) you will be fine.
> ...


I vary groups each time. Each group only has 1 MOA so I never apply more than one. All these below are what I rotate, they are all in different groups and different MOAs.

Cleary's 3336f
Eagle 20EW
Daconil Ultrex
Palladium

I also keep Aliette WDG and Segway on hand, These 2 can target several diseases that most cannot. They have very low limits to max apps per year so they are not used as preventative. I used them to eliminate Pythium Root Rot and Yellow Tuft when all others failed. Segway is obnoxiously expensive, but one of the best options for root dysfunction.


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## DFW St Aug (10 mo ago)

Austinite said:


> DFW St Aug said:
> 
> 
> > Austinite said:
> ...


I appreciate the info. I had not heard of Palladium before. I will keep the expensive stuff in mind in case I run into problems this summer.


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## DFW St Aug (10 mo ago)

I'll try to keep this thread updated periodically throughout the season with the status of my turf.

I ordered a new battery powered tank sprayer, and have some Abound and Drexel Chlorothalonil 720 on the way. I am going to order some Eagle 20EW and Quali-Pro TM 4.5 this week as well.

I applied the bag of Pillar G I had on 3/26. Starting on 4/23, I am going to start this rotation every 14 days:

Abound .38 oz/K

Chl 2.12 oz/K

Eagle 20 1 oz/K

TM 1.75 oz/K

I know Azoxystrobin is supposed to be good for 28 days, but I figured it wouldn't hurt to apply something else after 14 days. Can Abound and Chl be mixed in the same application? I know that Abound needs to be watered in to work, so would applying them together be OK as long as I waited a day or two to water? If that is possible, I may also apply it with Abound at the beginning of the cycle.


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## mjh648 (Sep 1, 2020)

Azoxy, Myclobutanil, and Thiophanate-methyl should do the trick for St. Aug rotation but as other users said really hone in on why the fungus is appearing and remedy the solution that way. Cut down on nitrogen when gray leaf spot pops up. Also maybe you are watering too much around then or keeping the grass too tall. Toss in a contact fungicide like Chlorothalonil on it in addition to the systemic rotation you are using but generally speaking gray leaf spot is not a big issue.


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## DFW St Aug (10 mo ago)

mjh648 said:


> Azoxy, Myclobutanil, and Thiophanate-methyl should do the trick for St. Aug rotation but as other users said really hone in on why the fungus is appearing and remedy the solution that way. Cut down on nitrogen when gray leaf spot pops up. Also maybe you are watering too much around then or keeping the grass too tall. Toss in a contact fungicide like Chlorothalonil on it in addition to the systemic rotation you are using but generally speaking gray leaf spot is not a big issue.


I always go low N in the summer, and I don't overwater. This area of North Texas always has lawn fungus issues because the temperature and humidity can and do frequently shift very quickly. Last year, we had much higher humidity than normal, and there was not a St. Augustine lawn in the area that did not have gray leaf spot in a fairly major way.

This year, I am trying to stay further ahead with preventative treatments to see if I can avoid an issue later in the season. I think having a fungicide plan is the only way to maintain a good looking St. Augustine lawn in this part of Texas.

Thanks for your feedback on the fungicides. I was trying to find something new, so the Myclobutanil replaces Propiconazole and the Chlorothalonil is a new addition.

Edit: I was asking for advice here on a granular summer fert. I appreciate any opinions.

https://thelawnforum.com/viewtopic.php?f=24&t=34923


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## DFW St Aug (10 mo ago)

For anyone reading this thread, the goal is to not see disease rather than treat it when visible this season. In North Texas, it is possible to "do everything right" and still have disease issues. I am going to document all my fungicide apps this season and will report if I am clear all season for others in this area. Unless otherwise noted, all apps are at the preventive rate.

I put down Azoxystrobin last week and I will rotate from Group 11 next month. We also had very heavy rain here Sunday night/Monday morning, so I put down some Chlorothalonil yesterday. My irrigation is off for the rest of the week, and I knew avoiding contact with the lawn for a few days would be possible. Our temperatures are always up and down this time of year, humidity is up and down, and there is a lot of dew on the ground most mornings.

If the weather continues to be irregular, I will put down Chlorothalonil again in 2 weeks. Otherwise, I will apply either Myclobutanil or Thiophanate-methyl before/by May 19.

3/26 Pillar G
4/21 Azoxystrobin
4/26 Chlorothalonil


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## ionicatoms (Mar 8, 2020)

DFW St Aug said:


> For anyone reading this thread, the goal is to not see disease rather than treat it when visible this season. In North Texas, it is possible to "do everything right" and still have disease issues.


I'm afraid you won't like this, but....

IMO the schedule-driven approach is neither necessary nor desirable. Fungicides such as TM negatively impact microbes for a period of time after application. This, in turn, affects the thatch build-up and feeding and resilience of the lawn. Insecticides can do the same. Every intervention comes with a risk of triggering some other additional intervention. Before you know it, you're looking around at your neighbors wondering why they don't have as many issues despite not really caring for their lawns.

For me, after doing "everything right," the question is more about "right product, right place, right time." Journaling (eventually) produces credible answers to these questions. Furthermore, it is never the case that you're doing everything right. This isn't a knock against you; it's just an admission of the impossibility of achieving perfection with a species that is incredibly sensitive to inputs and its environment. I think it's like Allyn Hane says, "The weather always wins." And weather isn't the only thing that matters. Cultivation matters. As the lawn thickens up, you get new problems which require adaptation.

In short, Rotation good. Applying blindly every 2 weeks, bad.


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## mjh648 (Sep 1, 2020)

@ionicatoms TM also does a good number on Earthworms. Appears as though the Chlorantraniliprole interval applications doesn't seem to affect soil health or earthworm population so the Grubex sod webworm schedule might not be that bad. Now you have me looking up each AI to see if I can find certain rotations that pose lower risks.


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## DFW St Aug (10 mo ago)

@ionicatoms I know there is a tradeoff, however disease stress has been worse in recent years, especially last year. The goal is to make it through this season healthy and reevaluate after.

I am definitely not blindly applying fungicide every 2 weeks. This is a very tough time of year here for fungus. Whether or not I apply more Chl in 2 weeks depends on the weather. It also depends on what I see in other lawns in my neighborhood.


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## DFW St Aug (10 mo ago)

mjh648 said:


> @ionicatoms TM also does a good number on Earthworms. Appears as though the Chlorantraniliprole interval applications doesn't seem to affect soil health or earthworm population so the Grubex sod webworm schedule might not be that bad. Now you have me looking up each AI to see if I can find certain rotations that pose lower risks.


Chlorothalonil. I think you are referring to something else.


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## mjh648 (Sep 1, 2020)

@DFW St Aug I'm referring to the AI in Grubex for a 60 day interval preventative application to control sod webworms that @ionicatoms adopted a couple seasons ago. A little off topic I admit but it tied into his comment


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## DFW St Aug (10 mo ago)

mjh648 said:


> @DFW St Aug I'm referring to the AI in Grubex for a 60 day interval preventative application to control sod webworms that @ionicatoms adopted a couple seasons ago. A little off topic I admit but it tied into his comment


I just recently joined here, so I have no idea what you are talking about. Please share.

There are a lot of people on here who overlap fungicides all season long, especially in tough areas for fungus like North Texas. I am certainly not the only one doing this, and the products I am using are in line with what most also seem to be using. I am aware of what the yearly limits are with these products, and am timing the TM for when I think it will be most useful. I am also using the preventative rates which is certainly better for the soil that waiting for a major gray leaf problem this season and throwing down multiple curative rates of fungicides.


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## ionicatoms (Mar 8, 2020)

@DFW St Aug

I understand the reason for confusion; the common thread is adverse consequences from product applications. TM reduces earthworm population, and so does imidacloprid. Instead of using imidacloprid, I use chlorantraniliprole, which is (now) the active ingredient of GrubEx1. It seems to be the case that chlorantraniliprole does not have an adverse impact on earthworms. In my mind, this makes GrubEx/Acelepryn a superior product.

Based on previous interactions, I think @mjh648 and I share a mutual concern for the responsible use of pesticides. I think (maybe) you saw a message posted by @440mag which mentions a 28 day standard program. The point being that for every person you point to who claims to be doing fungicide "all season long," I can find counter-examples where rotations are applied less frequently than every 14 days. I think @440mag's approach is on the right track because it's informed by journaling and technical criteria. He doesn't appear to include a time component, an example of which would be "humidity above a certain level for a duration exceeding X hours," but I wouldn't be surprised to see that as part of the heuristic he uses. I admit this is speculation.

It's good that you are aware of annual maximums. That wasn't clear to me at the time I read your request for feedback. It also wasn't clear if you understood that chlorothalonil is not labeled for residential use, and that overuse or sequential use of TM comes with a high risk of resistance. It wasn't clear to me if you understood the difference between systemic fungicide (e.g. azoxystrobin) and contact fungicide (chl).

Your last response is informative, but also does seem a bit defensive. At no point did I intend to suggest that what you're proposing is unusual. The bottom line for me is that a goal of literally zero fungus is unreasonable and unnecessary, and that pursuing such a goal year after year is inevitably going to be frustrating and cause other problems. And I don't think anybody has even brought up the issue of cost yet. Guys like @CenlaLowell and @Darth_V8r have posted a lot of good information about "the trouble with St. Augustine." From an "enjoying the hobby" standpoint, I think it's super important to manage our expectations when it comes to St. Aug.


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## DFW St Aug (10 mo ago)

@ionicatoms I'm not being defensive at all, but I am responding to criticism against my plan which is part of the overall discussion. When you made the comment about applying "blindly," I felt the need to explain myself. To be honest, from the amount of detail in my first post I feel like it should have been obvious that I am not a newbie. I do know the difference between systemic and contact fungicides, and I know all about Chlorothalonil and have made my own decision based on my situation.

My main concern going into this season that I tried to highlight from my first post was that the older strategy I had used for years stopped working so well last year. That is why I dropped (for now) Propiconazole altogether. If Azoxystrobin was not so cheap, I would have also avoided it this season as well.

I don't expect to have "literally zero" fungus in my lawn, but I am aiming as much as possible this year to avoid visible signs of fungus. Perhaps if you were familiar with the weather patterns in this area you would understand why I am taking this approach this season.


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## ionicatoms (Mar 8, 2020)

Yes, your plan will reduce visible signs of fungus. Potassium and silica are also known to reduce the frequency of Gray Leaf spot. Sorry, I took your statement "the goal is to not see disease" literally.


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## DFW St Aug (10 mo ago)

ionicatoms said:


> Yes, your plan will reduce visible signs of fungus. Potassium and silica are also known to reduce the frequency of Gray Leaf spot. Sorry, I took your statement "the goal is to not see disease" literally.


Thanks for the recommendations. I definitely stay on top of potassium, but silica is new to me. If you have any recommended reading, please share it.


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## ionicatoms (Mar 8, 2020)

https://apsjournals.apsnet.org/doi/epdf/10.1094/PDIS.2004.88.4.338


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## DFW St Aug (10 mo ago)

3/26 Pillar G (bag rate)
4/21 Azoxystrobin .37 oz/1K
4/26 Chlorothalonil 2.12 oz/1K
5/14 Myclobutanil 1.5oz/1K

Based on disease that I have seen in my neighborhood, I put this down just a little bit early today. I also decided to apply products slightly above the "minimum," but not so high that I get into curative rate territory. That's why I applied 1.5 instead of 1.2 oz per 1K. My turf still looks healthy, but there are plenty of diseases already in lawns with the temperature and humidity fluctuations.

I ended up not applying more Chlorothalonil because my lawn looked fine. My next app is going to be TM at a preventative rate. We already have some gray leaf spot in the neighborhood, but none in my turf so far.

Mods, you can move this to the Pest Control forum if you want. I started this when I first joined and wasn't sure where to post. This is NOT going to be lawn journal, so please don't move it there.


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