Question
I have a very big problem with acorns my yard and patio are covered with them the tree is very large & I had the tree trimmed but it did not help the man who trimmed it told me that for $400 he could inject the tree with something that would sterilize it and I would not have any more accorns, my question is could that be possible? and will it harm the tree itself

Answer
I do not know of a injection system that will stop acorn production.
Maybe possible but not practicable. What needs to be done is stop the flower formation. It is possible to spray the oak each year with a plant growth regulator to prevent acorn formation An ethephon spray during flowering is recommended to prevent acorn formation but correct timing of the spray is critical.

A garden center may sell ethephon under a trade name such as Florel. Ethephon breaks down to release the plant hormone ethylene. A homeowner may find it most efficient to hire an arborist to spray their trees because an expensive sprayer is required for tall trees. .

The good thing is the production of  acorns will vary greatly by year depending on the weather (frost usually) during the time they are flowering.

Here is a link to the web for Certified Arborist--I would only use one that is certified.

http://www.isa-arbor.com/findArborist/findarborist.aspx