Oak leaves a detriment to grass?

I have a new lawn, seeded last fall. I got a great stand, and it's looking great this spring. The problem? Two to three foot square brown patches are appearing. Could this be due to oak leaves falling from my large pin oak?

I would think that the leaves would have to be piled a few inches deep to kill off the grass...is it areas only under the tree, or across the lawn?

I rake the leaves, but some stick. The guys who mow my lawn (and did a great job planting new grass last fall) say the leaves, I guess even still on the tree, contain an acid that grass doesn't like. What do you think?

Shade and tree roots competing for water are also not ideal conditions for growing grass, so regardless of what's causing these particular brown spots you may always have some trouble growing grass under the tree.

I have a mix of St Augustine and centipede grass in my yard. I have a large old Live oak and a large Pin oak. My husband has a lawn sweeper that he runs after mowing (cutting the leaves with the mower helps them break down faster). Everything goes into the mulch bin.

We limbed up the Live oak some to allow better light and made the area under it a shade garden.Whatever leaves fall there pretty much stay there. As for the pin oak, the grass grows quite well under it. I have a circular bed around it full of gingers hostas and indigofera...biggest problem is keeping the grass out of the bed. Check out this link

http://iloveturf.com/library/articles/oak-leaves-do-not-kill-st-augustine-lawns-%E2%80%93-oak-leaves-are-good-lawn.

in this pic you can see both trees, the pin oak is to the right

All are correct, large rooted trees and leaves are not the best mix for a good lawn, IF it makes life easier for you come autumn, I raise the cutting blades from my lawn mower and run that over the lawn, it doesn't cut the lawn but the mower chops and lifts the leaves, it makes a tidy winter lawn and saves the grass from unwanted shade from either the leaves or the decaying leaves ad they die off. not all grass can take decaying leaves for more than a few weeks but when they constantly fall onto the same area, the lawn gets deprived of light, water, air and some leaves are bad for the lawn as they decay they release a poison to grass sheafs / leaves. there is no way to prevent this other than treeless gardens and who wants that eh, some folks chop lower limbs off the trees and this can help but get an expert to do this as they know how to balance the boughs of the trees to make them both safe and attractive. I would; aerate the lawn area with garden fork then feed a spring feed to green up the area and after that, look see what can be done to prevent recurrence of the same problems over the summer months. good luck. WeeNel.