Lack of N is one of the main culprits. Are you putting enough N down???

tbonejones:

5B zone says nothing really. Where do you live? (can I guess? Some place that is damp and humid in August, eh?)

Some grasses are more suspect to rust than others. What kind of grass do you have - and be specific?

>"lawn is too dry, cutting too short"

Whoever told you that about rust - run away. Google is our friend, not the person who gave you THAT advice. Genetics and mother nature cause rust first and foremost. Cultural practices second.

And yes, the grass will out grow the rust and the weather conditions will change. Nitrogen, like my friend formicburn says helps with a growth flush. And when do you apply N? When conditions/weather favor a growth flush after the rust conditions prevail, in fall.

Let's start with the basics. Lawn Rust is a fungus. It grows best in warm, humid conditions. It spreads through spores. It grows relatively slowly compared to most lawn diseases. It typically does not kill the grass it infests unless there is some other major, underlying problem.

So, how does that apply in your case? In august, your cool season grass is at its low point. It is stressed and growing pretty slowly. On the flip side, the rust fungus is loving the warm, humid temps. Even though it isn't growing so fast itself, it overtakes the grass. Come fall, the temps drop. Your grass starts growing faster and the fungus starts slowing down. The grass starts to win. The symptoms disappear, but the fungus is still there. The spores have no problem over wintering in your yard and the disease flares up again when conditions are favorable.

Don't worry though. You can break the cycle. Your best bet is a 3 part plan.

The first part is optimizing your grass growth. This problem effects grass at its weakest time, so anything you can do to strengthen the grass in summer will help. Get a soil test to see if growth conditions are optimal. You may need to add lime to adjust the PH or you may be low in certain nutrients. Make sure to keep the area watered once a week if it doesn't rain so the grass keep growing. I would try a mild, organic fertilizer (like cornmeal) in July as well.

The second part is minimizing the outbreaks. Make sure you are watering in the mornings only so that the area doesn't stay wet all night. If you have anything disrupting airflow (like low hanging trees) you should trim it back as much as possible. After each mowing, wash the mower deck and wheels and spray with a diluted bleach solution to sterilize them. If you have an outbreak of rust, bag the clippings until you get it under control. Minimize traffic on the infected areas to avoid spreading the spores. The better you control the outbreaks this year, the less spores you will have floating around to give you trouble next year.

The third part is long term management. Some grasses are just affected more by rust that others. You should plan on overseeding with some rust resistant types. That way, the grass itself will fight much of the battle for you.

Best of Luck

quite a bit of good info in previous posts.

In my experience, mostly a severe pest of common ryegrasses. Can also be a problem on some bluegrasses, but is always a complaint on certain Rye only lawns. Also seemed to be worse on newer lawns on rotten soil (surprise, surprise...) lots of Rye and rotten growing conditions.

N does help but also one needs to apply it and irrigate heavily prior to severe onset to keep the grass growing aggressively. Bagging may help somewhat but the spores are everywhere in the fall (even on your neighbors lawn--he just has a non-susceptible or less susceptible variety).

In central PA, Southern NJ, RI and eastern CT (my personal realm of turfcare experience), I NEVER saw rust on a lawn in the Spring or Summer. It was exclusively a Fall disease. What I was told by various academics was that it did not overwinter in the 'North', but rather arrived annually on large storms that come up from down south where it can survive year round. That always made some sense when I thought of Hurricane seasons onset and the arrival of rust in lawns.

If you have a Rye lawn, don't worry as Spring will allow for you to get 'red thread' infestations. I almost always saw it on the same lawns in the Spring that had been rusted up in the Fall. Though red thread will also affect other grasses as well. Same cultural practices apply (N + H20) to 'grow' that out although bagging clippings always seemed more effective at limiting the spread.

I never recommended fungicides on home lawns (too expensive, needed too often and only effective preventatively). A recipe for failure at high cost if ever I saw one. It always made much more sense to either overseed with resistant varieties (in cases of mild disease infestations) or Glyphosphate and switch to a different turf (Tall Fescue or Kentucky Bluegrass).

So the answer is : It will be there every Fall. You can chose to give it something different to try to grow on by renovation with a better type of turf.

There are three things necessary for any disease to be active. You need a 'Host', a 'Pathogen' and Environment(advantageous environmental conditions). Remove any of those three things and the disease will not occur. Fungicides, in one way or another, modify (though temporarily) the environment. This principal actually relates to ANY disease scenario...from mildew on your shower curtain (Bathroom fans,and windows are also attempts to modify that micro environment) to bread mold. Since Pathogens are generally thought of as omnipresent...you can change the host or modify the environment.

One caveat: Changing hosts often just changes which diseases are possible. The problem can change with the host. But, I never thought losing rye for either TF or KY blue was a bad trade.