I live close to the river valley and we have a porcupine that comes over our 6 foot fence & raids our yard. So far he has sheered off the raspberry canes and polished off half of my climbing roses. I have found repellants for groundhogs, racoons, deer, skunks, squirrels, dogs & cats, but nothing for porcupines. Any suggestions? I would prefer a chemical or even electronic deterrant over a physical barrier as he can climb over the fence at any location and I cannot barricade my entire garden! I have heard about gadgets that emit high frequency sound waves - anybody know if they work on porcupines?