Lawn Fertilizer around mature oak trees?

If you read the bag, weed and feed fertilizers tell you to avoid the drip line of bushes and trees. A landscaper told me atrazine can build up in the soil and kill your trees over several years. One year will not hurt it. For this reason, I only use fertilizer, no weed killer. Research what is the best ratio for your grass. Louisiana agcenter has great info on their website.

Don't know about the oaks, but Bonus S will knock citrus' dick in the dirt.

LSU Ag center does have some great info on preserving old oak trees.

Be careful because you can really stress an old oak with improper plantings, fertilizing, and trimming.

It might sound silly but if they are very old oaks, you may want to consult an tree consultant.