I have a number of 5-gallon citrus that have been grafted to the rootstock about 18" of the trunk. Now half the canopies on many of them are tri-foliate alongside the grafted citrus. Is it practical to cut back these suckers or will it be an ongoing process? What are the chances the rootstock will take over completely? Any suggestions for ongoing care if these are planted in clayey soil SW of the Phoenix area?

You can always cut off the rootstock limbs but I'm guessing you got the trees from HD, due to the fact there on tri-foliate roots, If so, they came from Willits-Newcome, ,, your going to have a hard time with them in your area because of the salts you have in the soils where you are. Add Gypsum each time you fertilize, and deep water.