I find the 15 to 17 foot lengths provide some support for the limbs as the trees get older. Somewhat helps keep limbs from breaking if you get a heavy apple crop. About 10 years back, with the deep snow, I did get some browsing over the four foot cages. More than just nibbling around the edges.
Apples do fall in the bigger cages, and I remove them to reduce disease in the next crop. This applies more so to the apples in my yard, not those for the deer that get less attention.
I use mulch around the tree. Also put leftover tree tubes of various lengths around the trunk to keep away rodents. Either tie this to the trunk of bigger trees or if there is a gap between the tube and the tree, I place a chunk of Tomcat rodenticide in the tube. Works most of the time. And the tube keeps the tree from splitting from the winter sun.
Charlie Morse suggested 5 foot fencing cut into 10 foot lengths. I will try this on some of the smaller trees that I ordererd from him. He also advised me to split the tubes over young trees and put a block in the split for the fall/winter to harden off the new growth. I had tried this in the past and suffered winter damage, but did not leave the block in all winter, only for the fall. He says the warming/cooling cycle during winter can kill the new growth in the tubes. Maybe I should give the tubes another try. I struggled with them on many kinds of trees in the past.
Healthy Habitat, Healthy Deer, Less Antler Obsession-All for the Sake of our Hunting Tradition
NRA Life Member
Muskies, Inc. Life Member
Minnesota Deer Hunters Association