Question
I have been requesting my landscape company to follow a careful maintenance program throughout the summer. It was work I expected would have to be done because my lawn is a Kentucky Bluegrass strain. The house looks nice most of the time but toward the end of the summer the grass began to look less healthy.  The grass was yellow and brown and almost ruddy up and down.  They said it was a Fungus and said they would put down a fungicide to take care of the problem.  Now there are white circular splotches in different locations on the lawn.  This is also mold, according to them.  Since we have already treated the Lawn, I fail to understand why we would still have any fungus problem.  Do you know what is going on?  Would you be able to explain it to me?  Thank you for your words of wisdom.

P.S. I live in the 23081 zipcode in Virginia.

Answer
Your symptoms suggest a few possibilities.  I'll describe them, and then we'll go over why a Lawn already treated for Fungus can still get a Fungus when the ink on the Fungicide bill is barely dry.

'Fusarium Patch' (Microdochium nivalis) shows up as Yellow or Straw colored patches, often in Spring, but can appear after any spell of cool, wet weather when days are not warmer than 62 degrees F and nights do not get cooler than 33 degrees F.  Treatment includes holding off on heavy fertilization, especially the 'Winterization' that people like to do in fall; these late season Nitrogen applications push tender growth at the expense of strength.  A similar disease, Typhula Blight, has similar symptoms.

'Powdery Mildew' usually attacks sections of Shaded Bluegrass.  Several Fungi are responsible.  But temps are milder, at least 60 degrees, no warmer than 72 degrees F.  Your region appears to have been too warm to be conducive to a Powdery Mildew episode.

When I look at your 23081 zipcode's weather history, you had a short period of rain in early and late September.  Temps in early September hovered in the 80s, quite warm, but dropped later in the month -- too warm for Fusarium Patch.

Let's consider something else.

Root growth for KBG is strongest during Fall and Spring, peaking when Soil temps hit 60 degrees F.  Root growth slows down as temps rise above 70 degrees F.  Any chance your problem could be Grubs?  Have a look; tell me what's down there.

Before signing off, I want to mention one thing.

You have a Lawn service that you pay for to take care of your Grass.  About 1/2 the country, last I heard, pays someone else to mow and fertilize their Lawns.

Trouble is, these Lawn servicers are strictly hard laborers.  Much of the time, around here at least, they don't speak any English -- nothing wrong with that, mind you, but how do you expect someone who doesn't even speak English to READ a report on the 'Turfgrass insect pests in the Northeastern USA'.  Grubs hatch and feed on Grass roots in late Summer and Fall.  There's ongoing research, and lots that we already know thanks to previous research, but NONE of that has ever reached the brains of those landscapers who take care of your Lawn.

So what they do that I don't like is 'treat' Grass according to a schedule determined by the manufacturer, and designed not to grow healthy Grass but definitely designed to maximize profits for the manufacturer.  Those treatments -- fertilizer, grub killer, Fungicides, etc. -- make the Grass weak and vulnerable to attack.  Without it, most Lawns would be fine.

What say you?

THE LONG ISLAND GARDENER