I have a row (8)of Bradford Hollys. Planted two years ago they are growing very well. This Summere two of the plants have sent up a shoot each that is over 30 inches. No side branches have emergedfrom these tall shoots. My question is if I cut them back say to ariund 12 inches will that cause side branch to sprout? If not what can I do to encourage side branch growth? Thank you for sharing your knowledge.
You don't need to reduce the central leader so radically to promote lateral branching. Reducing by a few inches to one foot off the top will suppress "apical dominance" and allow lateral branching.
You can also use a plant growth regulator with the active ingredient of 'paclobutrazol' which suppresses the hormone that facilitates rapid vegetative growth and promotes a bushier growth habit. But it's expensive.
Also, don't fertilizer with a high nitrogen chemical fertilizer that promotes rapid vegetative growth. Use a balanced, slow release organic product like this: