605 ILCS 5/9-116
The owner of any hedge fence growing along the right-of-way line of any public highway shall during the year next after such hedge has obtained the age of 7 years and during each year thereafter, trim such hedge fence to a height not exceeding 5 feet, except for Osage hedge which shall be trimmed annually after the second year from the first trimming to a height not exceeding 4 feet, and the owner shall trim all such hedges on the road side so that foliage will not extend over the right-of-way line for a distance in excess of 4 feet. All such trimming so required shall be done prior to October first.
The highway authority having jurisdiction over the highway, upon application of the owner of a farm, may permit such owner to grow a hedge fence to any desired height for a distance not to exceed one-fourth the total length of the hedge fence along the highway to serve as a windbreak for livestock. Such permit is revocable at any time.
The provisions of this Section do not apply to any hedge protecting either an orchard or a building.
Any failure or refusal to comply with the provisions of this Section is a petty offense and is punishable by a fine of not less than $10 nor more than $50 for each year of such failure or refusal.
605 ILCS 5/9-116