Apple tree suckers
Hi, I have an apple tree stump that is in my back yard. I didn't know this when I purchased it as it looks like a bush with many small branches coming out of it but this year there is fruit on a few of the branches ( approximately 3 of the many). Is there a proper way to prune the tree to enhance the fruit growth and potentially have a full fledged apple tree again?
Outside United States
Those apples may not from the tree that was cut down but from the rootstock. Unfortunately apples are grown rootstocks. Apples do not grow true to type from the seeds they are all different, just like people. The desired variety is grafted onto a rootstock. Initially the rootstocks were seedlings themselves and all the trees were generally full sized trees. Some where much smaller and suckers from the roots of these smaller trees were used as size controlling rootstocks.
Suckers coming from the ground are the rootstock. Suckers coming from the stump may be the apple that was there.
Pruning delays fruiting. If you decide to keep some suckers from the trunk remove all the suckers you do not want early next spring before growth begins. I wouldn't do any pruning on the shoots you keep until the following year and then start to select which ones you want.
Here is a link to another question on pruning apples which gives good information on basic pruning of apple trees. https://ask.extension.org/questions/229774.