[CarolinaCuttin]

Hi all, first of all thank you for putting this together.

Looking for some feedback on my 2021 Fungicide preventative plan. I already own the fungicides listed.

Started taking care of my lawn myself this year (mostly TTTF) and had lots of fungus this year, and looking back on pics when I paid someone to maintain it, it looked like I had lots of fungus then too. This year I had Pythium, some brown patch (I think) and I think I am getting some leaf spot now (GLS is my thought, but not sure).

That said, my watering in 2021 will be substantially improved (deep and infrequent), which, alone may help prevent some fungus in and of itself.

I'm in Nashville with a long and hot, humid summer. I've done lots of research on this, but still have tons to learn and am curious on your thoughts. I realize this is a rather extreme (and expensive) preventative plan.

Another thought is to add in Enclave in lieu of some of the treatments for another MOA especially towards the late summer, early fall. I do not own that yet.

May 1
Azoxystrobin & Propiconazole 28 days

June 1
Thiophanate-Methyl & Mefenoxam 14 days

June 15th
Thiophanate-Methyl & Mefenoxam 14 days

July 1
Azoxystrobin & Propiconazole 28 days

Aug 1st
Thiophanate-Methyl & Mefenoxam 14 days

Aug 15th
Thiophanate-Methyl & Mefenoxam 14 days

Sept 1st
Azoxystrobin & Propiconazole 28 days

Sept 15th (Approx seeding time - lots of water and still bouts of humidity)
Thiophanate-Methyl & Mefenoxam 10 days

Sept 25th
Thiophanate-Methyl & Mefenoxam 10 days

Oct 5th (Oct can still be in the 80s sometimes and humid)
Azoxystrobin & Propiconazole 28 days

Thanks in advance.

Subdue (mefenoxam) has an extremely high risk of resistance development. I know azoxystrobin is labeled for pythium but it's not useful once the disease pops up and it only works okay as a preventative. Use mefenoxam only once you see pythium present and at seed down (one application only). Get some phosphites and spray every 14 days during the growing season foliarly (low carrier volume, don't water in). Phosphites are cheap, they have low use rates, and I'm sure you could do a split with someone if you wanted. They are great at preventing a pythium outbreak when applied successively and preventatively. Subdue is your last line of defense unless you buy something else, so don't render it unusable by spraying it with no rotational partners throughout the season. Never spray two successive applications of Subdue without tank mixing it with another fungicide labeled for pythium.

If your main concerns are pythium and brown patch, this is what I would do.

Pythium: Do not water unless the turf needs water. Water in the early morning if possible. Every 14 days spray foliar phosphites. Do not tank mix with other fertilizers except urea. Check compatibility before mixing phosphites with anything except urea. Shorten interval to 7 days during periods of high disease pressure. If breakthrough occurs, spray mefenoxam at the max rate allowed by the label.

If pythium is bad for you then you will need another fungicide. I'd need to check which ones are labeled for residential lawns but some things to look at are Fore (mancozeb), Segway (cyzamofid), and Banol (propamocarb).

Brown patch: Do not water unless the turf is telling you that it needs water. Water in the early morning if possible. Do not give the turf more than 0.4 lbs N/M monthly from June to August. Maintain the turf at the proper mowing height going into the summer, the goal is to make it through.

Start preventatively treating when nighttime lows get above 60° F for three consecutive nights. Use azoxystrobin on a 28 day rotation, thiophanate-methyl on a 14 day rotation, and propiconazole on a 14 day rotation. Suppose you look at the forecast and see on June 12th that you have the first string of 3 nights above 60° F for the year. This means it's time to start treating preventively in anticipation. Using this as an example:

June 10th: Propiconazole
June 24th: Thiophanate-methyl
July 8th: Azoxystrobin
August 5th: Propiconazole
August 19th: Thiophanate Methyl
September 2nd: Azoxystrobin

By the time the last azoxystrobin app wears off, you are probably out of the woods as far as brown patch, temps at night will be below 60° F. If you happen to see a breakthrough, raise the rates and shorten the interval for the next application. If you are managing your water properly I don't see how any brown patch will get through a program like this.

Regarding watering, I'm growing TTTF in SC and I like to wait to see the first (mild) signs of drought stress before putting any water down. The first signs are the leaf blade shrinking and getting thin and needle-like. I'm not saying you need to wait until it turns purple or brown, just wait until it starts to tell you it needs water.

Once I see stress, I pound it hard with water in the morning knowing that the roots will suck it up quickly and the sun will dry out the soil by sunset that night. The best disease prevention program is good management practices!

 

[lifeandmylens]

Thank you very much! This is excellent info for me to have. In the past I have definitely watered poorly and over watered. I will look into phosphites, I haven't heard of that yet.

What about tackling what I believe to be Gray Leaf Spot which has appeared early fall this year due to probably all the watering from the overseeding.

And then we get rains from the hurricanes that move up the country and it's always followed by cloudy days with high temps and humidity (how fun).

Currently my lawn is soaked from 3-4 inches of rain and the disease (what looks like melting out of new seedlings with some GLS looking spots on them too) is spreading. But the grass is still wet and tomorrow will be 80, cloudy and humid so not expecting it to dry tomorrow either. Guessing I should wait to treat it until it dries?

So would like to treat what I currently have going on. But also have a preventative plan in place for this new disease also.

 

[CarolinaCuttin]

@lifeandmylens One of the most important things with respect to pest management is proper identification. Can you get a picture of what you are seeing to see if we can make a confident ID? From far away, close up of affected plant, close up of leaf, etc.

You don't want to start throwing stuff down until you're sure what you have going on.

 

[lifeandmylens]

@lifeandmylens One of the most important things with respect to pest management is proper identification. Can you get a picture of what you are seeing to see if we can make a confident ID? From far away, close up of affected plant, close up of leaf, etc.

You don't want to start throwing stuff down until you're sure what you have going on.

Ok thank you.

Here are the newly seeded areas from further away:

And close ups (yellowing and small patches becoming sunken and slimy):

And blades (Seedling blades dying, older grass blades showing spots):

 

[CarolinaCuttin]

@lifeandmylens Yeah I'm agreeing with that diagnosis. What have you put down in the last 60 days and what dates for each app?

 

[lifeandmylens]

@lifeandmylens Yeah I'm agreeing with that diagnosis. What have you put down in the last 60 days and what dates for each app?

Ok thanks. I put down:

Azoxystrobin .4oz/M Aug 14th (preventative)

Propiconazole 1 oz/M at seeding (Sept 4th)

Mefenoxam 1 oz/M Sept 10th (knocked it out right away)

Mefenoxam 1 oz/M Sept 21st (didn't know better and put down another dose just in case per label)

My plan was going to be a curative rate of strobe tank mixed with either prop or clearys. Or possibly purchase Enclave knowing it may take a week to arrive. But open to your guidance.

 

[CarolinaCuttin]

@lifeandmylens If you want to treat for it, I would tank mix Azoxy and Cleary's for GLS, that will absolutely decimate it. It will also give you a month's worth of protection from any other issues that arise.

Enclave will do a fantastic job as well but keep in mind any product containing chlorothalonil is not labeled for application to residential lawns, including Enclave. Do with that info what you wish.

It looks like you have pooling of water on the turf near the cement pad around the pool. If you have standing water for multiple days after heavy rains, there isn't going to be a spray program good enough to keep the turf clean in those areas, the best bet is to sod cut those areas and grade it properly so that it runs down to the pine straw.

 

[lifeandmylens]

@CarolinaCuttin Thank you again!! You've been so helpful. A few follow up questions:

1) If I spray tomorrow and the grass is slightly wet (wont have rained for 24 hours, but still wet and then wet from dew) will that be ok, or should I wait for totally dry grass blades say in 2 days?
2) Should I use a surfactant with fungicides like 3336f and strobe? I find mixed answers on this online and no real info on the labels for turf.
3) Would you do anything differently than your suggested plan above to add prevention for GLS in 2021?
4) No N until this is cleaned up, right?

 

[CarolinaCuttin]

@lifeandmylens

1. You need this spray to hit the leaf blade and stay there. Spraying with a lot of dew or moisture on the leaf can cause some of the spray to fall off the leaf. Exactly how much you can get away with is something you'll have to be the judge of, you want the spray on the leaf and not messed with until it's dry.

2. Always read the label when looking for that info, if it were me I would not use one unless the label says one can/should be used. After reading the Strobe label, I would not use one.

3. Probably not, those three fungicides control GLS (but propiconazole doesn't do a great job) even though the program is built for brown patch management.

4. Yes definitely no N for at least a week or two, and I would consider waiting until November. By then the hurricane threat will be mostly gone and temps will be low enough to keep disease pressure down.

 

[lifeandmylens]

@CarolinaCuttin Thank you so much!

 

[lifeandmylens]

@CarolinaCuttin sprayed the Strobe+3336F today!

A couple more questions for you.

For the phosphites you mentioned for next year, something like this? https://www.domyown.com/phostrol-fungicide-p-21783.html

And finally, with GLS, I'll obviously bag clippings, but should I lower HOC to dry it out or keep around 3" which is what I currently have been cutting at after overseeding?

 

[CarolinaCuttin]

@lifeandmylens That's perfectly fine, but it isn't labeled for turf so there's no telling what else is in it or what rates to use. I use Phite 0-0-26 @ 3 oz/M and even with 3 straight days of rain and warm nights my bentgrass is clean as a whistle.

I would not cut it lower, I would maintain a low-stress HOC (3 inches sounds great) especially during periods of drought or high disease pressure.

 

[lifeandmylens]

@CarolinaCuttin thank you! I will keep it at 3".

Re: Phite 0-0-26 - since its potash will this raise potassium levels in my soil?

 

[CarolinaCuttin]

@CarolinaCuttin thank you! I will keep it at 3".

Re: Phite 0-0-26 - since its potash will this raise potassium levels in my soil?

It will slightly, I believe 3 oz per thousand is roughly 0.07 pounds of K per thousand. It's a very small amount but it is something.

However, so will the fungicide you linked to since it has potassium phosphite in it as well. The only difference is that the fungicide isn't required to give you a nutritional analysis.

 

[lifeandmylens]

@CarolinaCuttin thank you! I will keep it at 3".

Re: Phite 0-0-26 - since its potash will this raise potassium levels in my soil?

It will slightly, I believe 3 oz per thousand is roughly 0.07 pounds of K per thousand. It's a very small amount but it is something.

However, so will the fungicide you linked to since it has potassium phosphite in it as well. The only difference is that the fungicide isn't required to give you a nutritional analysis.

Thank you again! I will order some. Use every two weeks in the growing season, low carrier volume and spray maybe the opposite weeks that I put down a fungicide?

 

[CarolinaCuttin]

@lifeandmylens Yes, spray at 3 oz/M every 14 days, lower the interval to 7 days during periods of high disease pressure. I spray at 50 gallons per acre (1.15 gal/M) but anything close to 1 gal/M should be fine.

I haven't tried tank mixing it with anything except urea. No issues with urea but phosphites are very finicky, so you have to do a jar test before mixing with other products.

 

[lifeandmylens]

@CarolinaCuttin Understood. Ordered it. Thank you for all your help!

 

[slash8118]

Summer Patch question: NC State recommends: "Two to three applications on 28-day intervals provide excellent summer patch control in most situations."

That implies that SP is not a threat in mid/late Summer? Is this the case or do fungicide applications need to continue as long as soil temps are 65+?

 

[bernstem]

@slash8118 It likely depends on pressure and conditions. I have not found two applications to be sufficient, but it is very possible I am doing something else to increase my Summer Patch pressure. I would be interested to hear from people with good results with two applications.

 

[Copat]

attempting to wrap my head around all of the fungicide applications......What would be a straight forward granular plan that is easily accessible at the box stores/feed stores? TIA