I recently put down new topsoil and applied hydro seed in early September. I’ve noticed these lighter patches since the grass began to grow. The grass in these lighter areas is thinner and comes out more easily when raked. Some parts are flattening out no matter how short I mow. I stopped watering a few weeks ago since the yard is shaded and I spotted some fungus. I treated it with Scotts disease-X, and the fungus seems to be contained. New England has been in a drought, which might have helped a bit.
What do you think is causing these lighter spots and how can I help the grass survive?
That light green color is just young grass. That’s why the blades are thinner and floppy. It will darken and thicken as it grows. By spring, all those patches will look darker.
The new seed might have a different color than the older grass but that’s unlikely. It will probably mix well next season.
If it still looks patchy next August, consider getting more of the seed you used this year to overseed the area next fall. The new grass will match the old in color the following year.
EDIT: I just noticed you said the whole lawn is new. Forget the last two points, everything will appear uniform next year in both color and thickness.
@Keenan
Do you have an irrigation system? Maybe one sprinkler isn’t working well? It looks like a donut shape which can happen when sprinklers don’t have enough pressure.