What's up y'all, I took some time the last few weeks to focus on creating a new guide for you all around one of the topics that I see a lot of confusion about, fungicides.

Making another guest appearance is my friend, Matt Martin of The Grass Factor to get down in the science-y details for you.

This guide to fungicides is pretty long. If you want a PDF copy sent to you via email, click here and enter your email address.  

Without further adieu here is:

The Lawn Care Nut Ultimate Guide to Fungicides

By Allyn Hane and Matt Martin
Flowery writing, opinion, and stories: Allyn Hane, The Lawn Care Nut
Technical Truth and Knowledge: Matt Martin, The Grass Factor

Fungicides - they are in the top 5 of topics/questions I get asked here at LCN-HQ. Interestingly enough, after 15 years at TruGreen-ChemLawn, I don’t know much about them. Let me tell you a story.

In the late 90s and early 2000s at TruGreen in Chicago, we didn’t often apply fungicides to lawns, at least not for money. Don’t get me wrong; in many cases, they were needed.

Our quick release, synthetic nitrogen fertilizer applications (33-0-3 was a common analysis, 3lbs/100 = 1lb N/1000) coupled with rushing yet intermittent early summer heat and humidity in late May and June were often lynchpins to the disease triangle, thus releasing the scourge.

Dollar spot and to a lesser extent, brown patch, were evident most seasons. If red thread was bad in spring of a year and turf scars persisted as they often did - lawns looked freckled and weak. No one likes pink, yellow or tan pockmarks on their double dark KBG. Nightmares.

So what would we do? Not much. For those who complained, we’d go out on a service call, diagnose, tell the customer to “wait it out” and “mow tall, catch the clippings, irrigate only in the morning.”

The idea was, just keep to the basics of good cultural practice and let the lawn power through. For the most part, this was fine. The thing about it is though, it was probably us contributing to a lot of the fungal activity in the first place because of all the super high dosed quick release nitrogen we applied every 4 weeks.

Didn’t matter really though: our customers mostly knew what to expect from us, and that was a weed free lawn. We were good at killing weeds. Not so good at much else. Limitations in creativity with big-box lawn care and all that, anyway...

For the extreme cases, where someone was really making a stink about the early summer dollar spot in the 2-year-old sodded lawn in White Hawk in Crown Point, IN… ...for THOSE people, I did keep a special tank mix in the back of my favorite F-350. Banner Maxx. One heavy-handed squirt today, with a half rate followup 7 days later and dollar spot and every other brown spot would be vanished like magic. Especially if I dosed the lawn simultaneously with a shot of Starter Fert and we got some rain (with lightning) we’d be clear of the uglies inside of 14 days. I was a rubber-gloved magician. It’s a good thing service calls were free and my overall chemical cost was in line. It allowed me to experiment a little. I learned just enough to be dangerous and form my own opinions.

In this guide along with the companion video I produced, we are talking about 3 strategies of attack against lawn diseases. Below that, you will find the recommended products, their coverage and costs, along with what disease they are most effective against.

2 Groups of Fungicides

All of the following are ok for all grass types.

DeMethylation Inhibitor - Group 3

Matt Martin says:
DMI (DeMethylation Inhibitor - Group 3) fungicides work by blocking cell membrane production in certain fungi. Without this function, the fungi fails. DMIs pose a moderate risk for fungus resistance.

DMIs notably have a growth regulatory effect on turfgrasses. When applied foliarly or as soil drench, DMIs effect gibberellic acid pathways (gibberellic acids make plants reach towards light), and also negatively affects overall turf quality the warmer it is outside. Applied at max rate or greater, DMIs can cause slightly phytotoxic effects (yellowing of leaves).

DMIs are particularly affordable in relationship to the delivered result (they’re broad spectrum), but typically have a short residual.

DMI Fungicides: myclobutanil, propiconazole

Strobilurin -Group 11

Strobilurin (Group 11) fungicides inhibit cellular energy production causing failure of the target fungi. Strobilurins have a high risk for fungus resistance. Strobilurins are typically the most expensive of fungicide classes but offer the longest length of control and the greatest control in terms of efficacy.

Strobilurin fungicides: Heritage, Pillar G, Armada

Because both DMI and Strobilurin fungicides have moderate-to-high risk potential of resistance, it is best to combine them in single applications to attack or prevent diseases with two modes of action.

With two modes of action, it attacks fungi development two different ways which would require two lateral mutations of the fungi before it becomes resistant to the fungicide applied. Residual control does not increase in length of time, but the spectrum of control does increase.

Here is a visual representation of efficacy on common disease when using this 2 class attack (Allyn calls it the “bulletproof strategy” in the video.)

3 Strategies

Ok so I want to give you 3 options to consider.

The first is the one I’m using called the “bulletproof strategy.” The reason I call it this is that I want to give myself the best chance of surviving the next 30-45 days with little-to-no disease issue. After that, I’m banking on the fact that the weather patterns will normal out.

You see, as mentioned in the video, we have had several straight days of “all day rain” and little-to-no sunlight. Humidity has skyrocketed. In fact, the weather report reminds me of a girl I used to date in college, it’s seriously that bad:

Because of this, the chance for disease outbreak is high and in fact, as you can see in the video, I’ve got a couple issues with gray leaf spot and what looks to my like dollar spot. Time to get after it!

I applied Heritage granular, then immediately Eagle liquid.

This gives me the broadest spectrum of control with 2 modes of action. I like the liquid Eagle because it can get right on leaf tissue where dollar spot and leaf spot reside. The granular Heritage (Azoxystrobin) will get in via root uptake and work it’s magic systemically. (The Eagle does too).

Then, if symptoms persist, I can apply another application of Eagle 14-30 days later as needed. I can even do 2 more apps if I want. It’s giving me flexibility.

(I’ll actually be using Propiconazole for my next Group 3 app so I can show you how that looks. Either one can be used 2-3 times, you don’t have to mix up the Group3s)

Also, if you’ve been hammering your lawn with Group3 fungicides for years and are noticing resistance… this is your strategy.

The second strategy is for those of you who have not been hammering your lawn with anything the last few years or months but you are concerned with these recent moist and unpredictable weather patterns.

You should just pick one or the other and hope for the best. Get the Group 11 and apply, all good for 30 days. If you do find that’s not enough, you can always just hammer it again.

You could essentially do the same with the Group 3. Just grab our old standby Propiconazole and apply now, then again in 14 days and maybe even again 14 days after that, if needed.

Either way, the idea here is to prevent.

The third strategy is just for correctives, mostly talking about dollar spot. If you see it, squirt it. Pick a Group 3 and go. Again, Propiconazole is a great choice.

I know I have not covered all disease issues in this guide… but this is a good start. Below are some recommended products. You can decide on liquid or granular - whichever is easier for you, just don’t make a mess and wear your PPE.

Ferti-Lome F-Stop Fungicide (Granular) Class 3
Active Ingredient: myclobutanil
Size: 10 lbs
Application Rate: 4 lbs / 1,000 sq ft
Bag Covers: 2,500 sq ft
* Price: $27.99
Cost per 1,000 sq ft: $6.99
Application difficulty: easy

*Price is subject to change. This guide was written May 2018.

Would probably recommend as a preventative. Not the best for curative. Same active as Eagle, but may be easier for some homeowners

Myclobutanil has a relatively short residual approximately 7-10 days but is especially effective in controlling dollar spot.

Eagle 20EW Fungicide (Liquid Concentrate) Class 3

Active Ingredient: myclobutanil
Size: 16 oz
Application Rate: 1-2 oz / 1,000 sq ft
Bottle Covers: 16,000 sq ft @ 1oz rate; 8,000 sq ft @ 2oz rate
*Price : $43.76
Cost per 1,000 sq ft: $2.74 - $5.74
Application difficulty: medium

*Price is subject to change. This guide was written May 2018.

Good preventative also a class 3 may need to be tank mixed with another fungicide of different class for curative. Also great for apple scab prevention if get early enough when buds fall off (crab apple). Foliarly applied myclobutanil will be more effective against turf diseases, preventatively and curatively, than granular fungicides.

Propiconazole (Liquid Concentrate) Class 3

Active Ingredient: propiconazole
Size: 32 oz
Application Rate: 2 - 4 oz / 1,000 sq ft
Bottle Covers: 16,000 sq ft @ 2 oz rate; 8,000 sq ft @ 4 oz rate
*Price : $46.56
Cost per 1,000 sq ft: $2.91 - $5.82
Application difficulty: medium

*Price is subject to change. This guide was written May 2018.

Propiconazole is a DMI fungicide that has the most aggressive growth regulatory effects. With sequential applications, control of difficult summer diseases (patch diseases) can be controlled for short periods of time, but at the risk of phytotoxic effects. It is extremely broad spectrum, and offers the best bang for the buck in terms of diseases controlled or suppressed. When mixed with Heritage, propiconazole offers superior control.

Heritage G Fungicide (Granular) Class 11

Active Ingredient: Azoxystrobin
Size: 30 lbs
Application Rate: 2-4 lbs / 1,000 sq ft
Bag Covers: 15,000 @ 2 lb rate; 7,500 @ 4 lb rate
*Price : $86.50
Cost per 1,000 sq ft: $5.77 - $11.53
Application difficulty: easy

*Price is subject to change. This guide was written May 2018.

Azoxystrobin is a strobilurin fungicide, Group 11, that offers superior control of patch, spot, and pythium diseases. While it’s very expensive, it covers a broad spectrum of diseases and provides very quick, thorough, and residual control. Azoxystrobin is best known for its 28 day residual preventative and curative activity.

If you want to throw in some RGS at 3oz/gallon for your liquid applications, that’s a good idea.

You can also mix in BiFen if you want to kill mosquitos in the lawn at the same time.

This guide to fungicides is pretty long. If you want a PDF copy sent to you via email, click here and enter your email address.  

I hope this guide has been helpful to you, I’ll see you in the lawn!