I'm curious as to what others think about this as well. I know daniel and I were considering mowing lower....

Here in central NC I think you would get fungus no matter how high or low you cut. Our summer temps are typically in the upper 80's and mid 90's with night temps in the 70's along with high humidity and heavy dew each night. It's the ideal conditions for brown patch and possibly other types of fungus.

On the other side of that, the high heat and long periods without rain will wreak havoc with a low cut lawn, especially without irrigation. My lawn is 1/2 acre and being on city water it would run me over $150 per 1 full inch of irrigation so my only real option is to let the lawn go dormant. When the summer heat hits I go to 4.5" and will not mow at all once the rain stops. I feel my TTTF stands a better chance of making it being left long. Once we do finally get rain the lawn greens back up and I will mow. Just how it works here. This is my second year applying fungicides which has helped my summer survival rates tremendously so I will continue this routine.

Good points. Same type of summer weather here in NNJ.

The problem with mowing height is the universities. Every uni does a study to get the perfect mowing height. The problem is that mowing height only works within a few miles of wherever that university is. So if you live near Rutgers, you can use the Rutgers recommendation. If you live across the country, then don't use Rutgers values. The other problem is they micro measure these heights and give you something in between what a normal mower can produce. A mower might have 4 settings between 1.5 inches and 3.5 inches. But the universities will give you a number like 2.3586636 inches. They will show you several patches of grass mowed at 2.3809264 and 2.32549073457 and they will proclaim that 2.3586636 is the ultimate perfect mowing height. The university in the neighboring state will insist that 2.5643373 is a much better mowing height. I simply don't have time for that.

I like to keep it much more simple than that. In general most grasses should be mowed more toward higher than lower. The easiest way to say that is to mow at the mower's highest setting. But if you have bermuda, centipede, or creeping bentgrass, those should be mowed at the mower's lowest setting to get the best density. Those grasses can survive heat when mowed lower. There are a few exotic hybrids of prairie grasses that will do well mowed high or low. As mentioned the general problem with mowing low is the grass dries out very quickly after watering. Mowing the tops low will cause the plant to trim off roots which need more water to keep the plant green. So if you lower the height in the middle of summer, you are picking the worst time of year to lower it. But if you are getting regular summer rains, then that is the time to lower it if you want to.

Good points dchall.

I think our biggest issue is the dew. Right now my grass is damp by 8:30 in the evening and isn't fully dry until 9:30 to 10 in the morning. That ends up 12+ hours of the grass being damp and doesn't even factor in the afternoon thunderstorm which adds even more wet time. This year I was seeing lesions on the blades in mid April. None of my neighbors have fungal problems but their lawns are 90% crabgrass and other assorted weeds which aren't effected by fungus. As much as I hate it, I've come to the conclusion that fungicides are a necessity around here.

z t, where in the world are you? what grass are you growing? Some grasses can be mowed quite high while others need to be cut much lower and it depends on where in the world you are.

Tall, thick turf will provide shade and help trap moisture under the canopy. This can help if you are a drought scenario. However, if you are regularly watering a tall, thick cool season lawn in the summer heat, you are definitely inviting disease. The same thick canopy that traps moisture - beneficial in drought - also means that it takes the lawn longer to dry out. When you throw summer heat into the equation, you are inviting disease. The heat and moisture under a thick canopy can be trapped, which would be to the advantage of lawn diseases.

In my opinion - choose between:

A)

Taller grass (3.5-4 inches)

Fungicides (preventative)

No watering (unless absolutely necessary)

Or

B)

Shorter grass (2.5-3.0)

Weekly Watering

More frequent cuts

the vast majority of people scalp their lawn...I wonder if the people who are getting fungus on high cutting are ALSO regularly "feeding" their lawn a nitrogen fertilizer, because they've been brainwashed by the lawn-industrial complex that it's somehow necessary.

My lawn is not great. It has Poa trivialis infiltrating and one day long in the future I should just roundup the whole thing to start over. There's no way to selectively control that stuff. It's a mix of various fescues and probably some bluegrass and rye. BUT I always cut it high, and as a result it's the last lawn to turn brown in droughts, whereas pretty much all the other idiots in the neighborhood who scalp either end up with brown grass, or 100% crabgrass. It looks a damn sight better than most of these other 'lawns' aka Crabgrass fields. So few weeds can invade I only need to spot treat the odd crabgrass or dandelion in mine. For several years I did broadcast spraying to rescue it from what I inherited (probably another idiot who scalps) but it is no longer needed. Also don't need to cut it as often, which is better for air quality.

(Btw my lawn also has some areas of coumarin-scented buffalo grass, which is kind of nice. Basic philosophy is to allow any grass that doesn't look hideous or grow in a wild and invasive manner. So the buffalo grass can stay, while Carex, crab grass, and the dreaded goose grass have to go. Also, had a HUGE infestation of Microstegium from the prior owners, which I got rid of. Sadly, some ignorant neighbors have an entire backyard of it! )

In parts of my yard I allow some clumps of coarse and tall fescue get huge because they are in a semi-wetland and it's hard to mow except in the driest spells of autumn. Even in the wettest weather, like almost 40 inches of rain in a roughly 40 day period due to hurricane Irene and some erstwhile major storms, I've never seen any part of those clumps brown out from some kind of disease or fungus, nor has any part of my lawn. I only N fertilizer every few years. The one time I wanted to green it up I used iron and that seemed to help.

I would love to know the scientific justification for "some grasses need to be cut lower". The reminds me of hair stylists saying hair "needs to be conditioned". Industry sponsored pseudoscience. What, for millions of years could this grass only exist in nature because of a commensal relationship with some bird, that plucked each blade when it reached 2 inches, to make huge nests? LMAO. Sure, a bent grass might be bred to look good when it's scalped...and that's necessary for a golf putting green. But it's not going to die if it isn't scalped. And if you really need that look, and really want the busy mowing schedule and upkeep requirements, fine. In my opinion, at that point you might as well install astroturf. Just about as natural...and probably better for the environment.

Umm....

@davidrt28 Great, thanks for you ray of light. Most of us on here mow high but due to a wet spring/summer the fungus has been bad. Instead of bashing your neighbors maybe give them some tips so whatever is their lawn doesn't make it to your. Also poa is a pain, I believe I have both in my lawn. Sounds like annua can be eradicated but trivialis is difficult.

Thanks z t. I'm glad I wasn't too harsh sounding for everyone LOL.

There's generally no hope talking to neighbors about this kind of thing. At least around, "this is the way we always done things...yeehaw" LOL. And I live in one of the supposedly upscale neighborhoods of my rural Maryland county.

What's really awful are some HOAs. My parents live in a community in the DC area where you are required to cut the lawn short, BUT also required to have it weed free. Therefore, basically everyone has to be on some kind of chem-lawn type contract to control the weeds. These companies of course, also insist on giving the lawn "food". Therefore it grows fast and has to be cut twice a week to not look stubbly - often by the same lawn care companies $$$$ - during rainy spells. What a complete racket!

I should point out the Poa trivialis was here when I took over, of course. I didn't cause it. What would you expect for a lawn that was: onions, crabgrass, creeping charlie, etc. etc. Anything that can be selectively controlled, I have controlled for by now.

One final tip some people might not know.

Goose grass tried to start taking over my yard. Of course it doesn't respond to quinclorac - which for me controls crab grass superbly.

There is one selective for it - the oily stuff name forgotten at the moment. (oh, just came back to me: Acclaim) But let's say you miss a clump and it starts to go to hideous seed. Go ahead and spray with the selective. Give it about two weeks to die and dry out COMPLETELY. DO NOT cut the area...that would spread the seeds! Get a benzomatic weed burner and a can of CRC brakleen*, and FIRE BLAST that sh-t!!! You don't want to spray something like charcoal lighter fluid on _TO_ the ground before igniting it, because it will burn too deep and kill the good fescue roots. OTOH, the benzomatic weed burner itself just takes too long to fully destroy the seed heads in a clump with more than a couple plants. I guess you could stand there for 30 seconds waving back and forth but I prefer the big fireball approach LOL.

OBVIOUSLY, DO NOT DO THIS DURING A DROUGHT OR TIME OF ANY FIRE DANGER!!!!!! Have a source of water nearby!!! Dried thatch can start burning surprisingly quickly! Also legal disclaimer: I cannot be held responsible for misuse of this technique! It only takes about 3 seconds of spraying...the flame front is NOT going to travel back into the can, but if you freak out and throw the can (or propane cyl) into the fire, of course something could go wrong!

Now, all the grass will completely blacken out. Actually the still wet fescue is only semi-blackened, but the top is mostly killed as you'd expect. That CRC stuff makes a huge, hot flame which is why I selected it. But I kid you not, within 2-3 months, the fescue will grow right back and you will never know something like that happened. Of course, you can't do something like this in an HOA neighborhood.

I have done this several times in several areas, do it correctly and you will NOT see goose grass again.

The alternative is to get down on your hands and knees and pick every single seed head up without letting any drop. Be my guest! Or to use a pre-emergent next year...but sometimes I can't plan that far ahead. How would I remember where the clump had been? In fact you'd really have to treat the whole yard, and with 2+ acres of grass, that would get pricey by my standards. Of course, the best approach is just to spray the goose grass before it goes to seed.

* - non-chlorinated version, OBVIOUSLY