Left spot/melting out - When to go Nuclear?

[agn015]

I’ve been battling what I think is leaf spot/melting out for the last couple of years. Here’s some pictures of what I have at the moment. The lawn was seeded/over seeded between fall of 2017 and fall of 2018 so it’s still fairly young for kbg and tttf.





In 2018 I was still a novice and didn’t notice any disease pressure besides some very light rust/powdery mildew.

In 2019, I kept up with serenade apps but had a small section in full sun die off in mid July. It recovered in the fall but remained thin through the winter and stayed thin in early spring of 2020. It actually never seemed to fully recover. Here’s a couple pictures of the spot that died mid July 2019



In 2020, the quarantine helped me to be even better about keeping up serenade apps and minimizing drought stress on the turf (yes, I move around hose end sprinklers, I thankfully have a timer this year). I included nufilm p, kelp help and molasses in every serenade app and was able to keep the disease at bay. No turf was lost but it did thin out, especially as fall/winter approached.

This year it’s more of the same. The turf was slow to wake (but it seems most lawns were this year), even after following the aggressive N regimen. I actually think the regimen may have weakened the turf in the fall and encouraged thinning.

I’m wondering if it’s better to keep up the fight using serenade or if I would be better off going nuclear and drop a curative rate of disease ex? Even if I bomb only once on the entire turf then continue with serenade. Could that be all I need to clear out the bad and continue encouraging the good?

[agn015]

Here’s another photo of the spot that died mid July in 2019

[MorpheusPA]

I'd go nuclear the instant you see any sign of approaching disease. Serenade should, hopefully, keep the disease at bay and conditions may or may not be right for it to show its ugly head this summer.

But seriously, watch out. If you see anything, bomb the entire lawn, make sure nothing is untouched, and assure that the nukes cover everything with sufficient radiation to assure that all disease is nothing but a shadow on scorched concrete.

Curing before the disease is really there often doesn't do anything much (the disease isn't widespread yet, which would be the good outcome, or isn't yet on the lawn at all, the bad one). But it does kill a lot of helpful micros that are trying to use up space that the diseases can now use to flourish instead--and disease bacteria and fungi grow a lot faster than symbiotic ones do. These apps always come with a price.

[agn015]

Thank you Morph! It sounds like now is a good time to nuke!

This will be my first time using a real fungicide. Do you have any recommendations on which one I should use? I’ll have to do some more research on this too.

I’ve been very hesitant to reach for fungicides as I always see Andy posting about a pattern of people who keep reaching for them and create a vicious cycle. I’ve tried so hard over the last few years to not be that person. But I don’t think I have a choice. Hopefully the the serenade will keep it at bay in the future.

[MorpheusPA]

Neither leaf spot nor melting out has been anything I've fought, so I have no personal recommendations. Listen to others.

And yes, you don't want to keep reaching for the fungicides. But when you have a fungal problem, you have no choice. Just keep rotating them every time you use them (if possible). It helps avoid your disease fungi developing resistance.

Some will say (I say) that cracked corn or corn meal can help a wee bit with fungal resistance. 10 pounds per thousand, once a year. It's no great shakes and seems to be just the slightest bit of help, but I'll take what I can get. It's absolutely not a curative, however, and you're far past that point.

[agn015]

Thanks, hopefully I don’t have to keep reaching for them.

I’m a fan of cracked corn too. I’ve put it down for the last couple years starting at 10lbs/k and this year was my heaviest at about 30lb/k. If it’s helping keep the disease at bay I can only imagine how bad it would be without it. Some areas perked up as usual but others are still struggling so I’ll pick up some Scott’s disease ex to get the battle started

I’ll pause the serenade for now too since it seems like it will be wasteful to use that while the disease ex is active. I’ll probably pause my saw dust and coffee grounds apps too and I think I’ll switch to bagging my clippings even though I absolutely dread bagging.

[MorpheusPA]

All that makes absolutely perfect sense--except maybe pausing the Serenade, which will help combat the disease too. But I don't think stopping it will make a noticeable difference for a few weeks, either.

[rxrep]

The guide that I use is this:
http://www2.ca.uky.edu/agcomm/pubs/ppa/ppa1/ppa1.pdf
Azoxystrobin is awesome. Just don't apply more than two applications in a row without using a different fungicide with a different mechanism of action. As far as Leaf spot/melting out goes your best choices are Azoxystrobin and iprodione (both systemic) and Chlorthalonil and mancozeb (both contact fungicides). Good luck.

[agn015]

That’s a good point on the serenade Morpheus. I was thinking the azoxy would kill the bacteria in serenade, but it sounds like the serenade just has to stay on the leaf to be effective in preventing the bad guys from colonizing. The nu film will certainly help with that. I’ll keep the serenade flowing to help give the good guys a chance.

Thanks rxrep! That link is a great resource! I dropped curative rate of azoxy yesterday morning. I’m not home now but it was already looking a lot better before I left.