If you are renting a unit where there are dabgerous conditions on the grounds and the property management company is not responsive to you concerning the rotting trees on the property and rectifying the problem, I would write the company once a week for several weeks requesting the need to resolve the problem. Keep a copy of the letters for future use and need. You might wish to contact your local fire department to see if the trees pose a fire danger or some other governmental entity that has public safety duties concerning the problem you are writing about.From what you have written, you are not allowed under state law to make the the property conditions safe and then deduct the costs for doing so as to exterior issues of the rental.