Leaf stains on fresh concrete driveway not sealed yet
Tar leaf, simply known  as tar, is caused from the organic pigments that give leaves and pine cones their color get embedded in the micro-pores and small voids on the surface of the concrete. They can be hard to remove without a good detergent and some scrubbing action. The best detergent to use is one with bleaching action or ammonia. Typically detergents designed to remove organic stains (blood, food stains, etc.) work best. OxiClean is one example. Granular detergents offer an added benefit, because they provide additional friction when you scrub the surface.

Here are the basic steps to follow:

Use a pressure washer to remove all solid leaf matter and debris from the concrete.

Apply a household detergent (as recommended above) to damp concrete. Let it sit and wet out for a few minutes.

Scrub vigorously with a stiff broom or scrub brush.

Rinse the concrete with water until you remove all the soap.

If this procedure doesn't completely remove the stains, repeat the process.