Rust - wait it out some more?

[Green]

My 1K upper back lawn (TTTF/KBG mix) is sloped, and has had rust for a while now. I think it's 2 months. I've been doing everything culturally I can...including bag mowing when it was at its worst, always cleaning the mower after mowing that area each time, giving it a small shot of synthetic nitrogen (and Milorganite a few weeks before that when it was too hot). Unfortunately, I didn't keep up a proper Serenade program on that area, and before I knew it, it was too late...I had rust starting. I started Serenade after the rust had begun on that area, and the rust still spread. Maybe the Serenade slowed it down or limited the spreading somewhat. I'll never know.

The rust is bad enough that I had a lot of orange-brown grass. Today, it looks like it's just past its peak slightly. It's getting a little cooler, and I'm mowing a half inch lower now, so there are less "pustules". But I have a lot of dead, straw-colored grass blades now, as well as a decent amount of "rust" still. From what I've read, the grass crowns are probably fine, and new blades will grow once it cools down.

Is there any reason for using a fungicide at this point? And seeing that it's a foliar disease, I would think it would need a foliar app. I have granular stuff of various types, some of which is labeled for rust, though.

Or just keep giving it small shots of Nitrogen every week, and cleaning the mower after mowing that area?

[HoosierLawnGnome]

Yes, rust can weaken turf headed into winter and make it more susceptible to injury. 2 months sounds like a tough outbreak. If serenade isn't cutting it go with fungicides.

CT still has a month of top growth, no?

[HoosierLawnGnome]

Eta , bag mow regularly to remove it, dont overfertilize, water in the morning, apply fungicide, repeat the fungicide in a week. If Serenade hasn't worked go with something else. 2 months is a long time.

I haven't had luck with Serenade killing bad outbreaks. Maybe others have.

[Green]

Yeah, I should have almost 2 months of topgrowth left. But this area is a North-facing slope, so it's the very first to go into Winter dormancy, and the very last to wake up in Spring. Maybe 6 weeks of top growth left for that specific area.

For fungicides, I only have granular products on hand. I have Headway G, and Scotts brand Thiophanate Methyl.
I thought both were labeled for Rust, but the Scotts doesn't list it on the bag after I checked. This article does confirm that it is used on rust, however: https://www.uaex.edu/publications/pdf/FSA-7559.pdf

Since both fungicides are labeled for it, I could rotate them on the second application for resistance management.

[Green]

One more thing: I don't know if it's really been two months since the onset...but it's been bad for at least one month, and hasn't gotten much better. I think we're done with 90-degree heat, as of today...starting to get cooler. I also have a touch of rust in some other areas, but it's minor...not bad enough to do anything about like it is on the upper back lawn.

[lVlrBoJang1es]

I followed an every-other-week Serenade program this year with "proper" cultural practices and got HAMMERED with rust this year. Admittedly, i'm not perfect (neither is mother nature), but i feel i've done enough to steer my growing season towards success.

The rust in my lawn showed up in June (viewtopic.php?f=37&t=22648) and is currently at its' worst (now 4 months later). I've been bag mowing, fertilizing lightly (when the heat has died down), and continuing with Serenade in hopes that the problem will "sort itself out" as i've been advised through various resources.

There was a period between end of August/early September where i thought it was getting better (once i started fertilizing), but it REALLY exploded over the past 2 weeks with the heat wave we just had in the area - longest span of over 85 degree weather ALL year just hit here in the end of September...

I know there's a general consensus that rust doesn't have any detrimental effect on the turf, but i'm heavily persuaded, based on my experience this summer/early fall, that this claim is a load of crock. I've watched the patches of orange dust slowly materialize, and spread on (what looks like) healthy deep green turf which then turns straw like within a a few weeks. It's not that all the blades that go dead in appearance (only 25-50%), but enough to make these patches look pretty bad...

One may argue that this effect is not due to the rust alone, but i've seen no prominent visual evidence of anything else that may be causing this. I did have some minor leaf spot issues, but the damage that i'm seeing is localized ONLY to where the rust orange powder was/is.

I purchased myself some 41.8 Propiconazole that will last me a few years. I'm going out guns blazing as soon as the delivery arrives. I tried fighting this crap off "marathon" style, but i'm definitely going to "sprint to the finish" in the future with my chem fungicide next time i see the first signs of any fungal problems.

I don't mean to doom and gloom; i'm just sharing my experience.

[HoosierLawnGnome]

Agreed, Bojangles - I had prolonged rust in a few spots that killed the foliage down to the crown last fall. It can hurt your turf if you let it go crazy. It basically blocks the sun from getting to the plant. It came roaring back in the spring, but didn't look good heading into winter.

Rust is a disease that adheres to the foliage, and spreads via the wind. So, the best thing to hit it with is something that touches the fungus and kills it, or adheres to the foliage and helps the plant fight off the disease by blocking it from coming in contact with the plant. Ergo, chlorotholonyl is often used by professional turf managers. ( I don't like that it turns things a white hue, personally! )

Honestly if it's as bad as what I'm hearing (1 - 2 months, Serenade won't kill it, etc) - I'd apply a foliar contact fungicide that will kill what it touches and prevent new spores from colonizing on the foliage.

Granular products will help, but they won't kill what's already there as well by moving up from the roots to the foliage as something that will come in contact with it and kill it straight away. Those spores on the surface will still blow around and potentially infect another plant. You want to remove and kill what's there with bagging, while minimizing the conditions in which rust thrives as best you can.

If you do apply that granular fungicide - which require watering - don't do so in the evening and create another long, wet, cool night with lots of fertility in which rust will do better. Apply and water in the morning and let it dry out during the day.

And something like propacanizole is a lot less expensive than azoxystrobin (headway, heritage et al)

[greenrebellion]

Rust consumes my entire neighborhood every fall. For those trying to avoid fungicides, is there anything else besides Serenade one can use as a preventative? I've been applying Serenade to my reno every 7 days, but its concerning that lVlrBoJang1es didn't see much success from Serenade.

[Green]

I'm also seeing some leaf spot of some sort, and the rust is starting to happen on the TTTF, too...not just the KBG anymore. It has already killed a lot of KBG blades. I think what I'll do, is actually make the first app as a split app:

I'll use the granular Headway I have first. I'll stick with the lower end of the label rate. There's a trick you can use to get it to stick to the blades better and absorb...basically, you wet the grass, then apply it, let it sit a half hour, and then water your tenth of an inch. We're getting some rain tonight as well (finally...knock on wood). Going to do it right now so it dries.

Then, I can follow-up in a few days with a low rate of a liquid app containing more Propiconazole...just to get what's on the leaves. I have to buy that, but I think my local store has some.

[HoosierLawnGnome]

I have a working theory based on a few years' observations now at my home, which has a lot of fields close by usually filled with corn or soybeans.

My theory is that the rust from neighboring fields on corn and soybean plants gets kicked up in the air at harvest time and sticks to dew-y turf. There are 100s of acres of fields within < 1/2 mile of me. Last year while they were harvesting there was a pale yellow cloud all day in the air. Not too long thereafter my entire open yard was covered in rust. I've seen the cycle for a few seasons now.

SO - I'm getting proactive this year.

My plan is to spray before and right after the harvest. I'll ask farmer Bob to stop by. Heck, I might ask him to drop off any OM he doesn't want to haul the half mile up the street to his barn in my front yard too

Check out page two of each of these studies:

soybeans: https://www.extension.purdue.edu/extmed ... -161-W.pdf
corn: https://www.extension.purdue.edu/extmed ... -160-w.pdf
wheat: https://www.extension.purdue.edu/extmed ... -162-W.pdf

propiconazole is given the highest ranking of all items there for rust on all these crop plants. I'm pretty sure that's what blows onto my lawn every fall

[Green]

Eta , bag mow regularly to remove it, dont overfertilize, water in the morning, apply fungicide, repeat the fungicide in a week.

Are you saying that you would spray Propiconazole again on any areas still with active rust, even though spraying twice with the same AI has a chance of contributing to resistance?

[lVlrBoJang1es]

Eta , bag mow regularly to remove it, dont overfertilize, water in the morning, apply fungicide, repeat the fungicide in a week.

Are you saying that you would spray Propiconazole again on any areas still with active rust, even though spraying twice with the same AI has a chance of contributing to resistance?

I'm going to.

I'm telling myself that two full strength apps won't be enough to build i resistance. I personally wouldn't hit this concern until i was doing multiple apps throughout the year.

I was shocked how quickly my lawn bounced back after my first Propiconazole app (0.73 Oz/k). I can definitely still see rust in some areas, but i'd say about 75% of it was wiped out. I'm due for another this weekend - hopefully that'll wipe the remaining out.

Leaves are starting to fall in my area - i'm hoping i can have this rust outbreak completely controlled before the leaves REALLY start to come down. I don't want to miss out by bag mowing my only source of OM for the year!

[HoosierLawnGnome]

Two sprays in a row isn't going to create a resistance issue.

[JohnP]

Two sprays in a row isn't going to create a resistance issue.

I've seen some people on here talk weekly Serenade apps, I'm assuming they've had issues before and we're doing proactive treatments rather than reactive, but I don't remember who it was or where I read it.

If you were doing preventative treatments with Serenade would you have a maximum in mind before quitting or cycling?

[Green]

Mine is bouncing back, too...not sure how much of that from the Nitrogen apps from the past month and how much is from the fungicide...but it does seem to be helping. Some areas are really far gone...brown...I might spray Miracle Gro on those areas. I'll do a second Propiconazole spray on at least the areas that still look bad.

[Green]

Thanks for the advice.

When spraying Propiconazole for rust, do you guys spray on dry or moist grass, and do you think it makes a difference?

[lVlrBoJang1es]

Thanks for the advice.

When spraying Propiconazole for rust, do you guys spray on dry or moist grass, and do you think it makes a difference?

I think it depends on what you're trying to control:

If it's a root based fungus, you'll be watering the application in afterwards, so i don't think applying it while the grass is moist would matter.

If you're going for foliar control, i would think that you want the grass as dry as possible when applying. I think this is further supported by the fact that the label states to apply after mowing. Although the intent of the label is to not chop the blades off where the stuff has been recently applied, i think this statement is relevant to your question since most people don't mow when the grass is moist. I may be reading between the lines too much here...

Notice all the "i think"s - experts correct me if i'm wrong.

[Green]

I asked because I read something recently (can't remember where) about applying to damp grass for foliar control. They didn't make it clear though, if they were talking about spray applications or granular applications. Granular applications, when used on a foliar disease, should always be made on damp grass and allowed to sit for a little while before watering in. But I'm wondering if liquids absorb (or is it adsorb?) better on dry or slightly moist grass.

[HoosierLawnGnome]

Liquids generally absorb into material that isn't already saturated better than those that are.

[Green]

Thanks. I was defaulting toward dry grass, anyway.

In other news, it's really starting to recover now...not just my imagination. I guess the fungicide is really working...the green color is actually coming back!