I bought this honey locust 3 yrs ago . It looked beautiful last year, but this year it grew all new shoots and the old branches are bare. I don’t know why it did this and do I remove all the old branches in the fall or leave it alone.
Thank you for contacting the Toronto Master Gardeners concering your sunburst locust.
This year there many landscape professionals have reported seeing significant canopy dieback in Maples, Yellowwood and honeylocust trees. Seeing Dieback in Maples by Jen Llewellyn gives detailed information as to what could be the cause.
Deciduous trees can and should be pruned at any time to remove any branches that are dead or diseased, or for shape. Many experts say that winter is in fact the best time to prune trees because they are dormant and it is possible to see the tree’s shape clearly once the leaves have fallen.
You should, however, be wary of pruning your honey locust (Gleditsia) as spring approaches and the sap begins to run. Like some other deciduous trees such as maples and lindens that bleed sap profusely in spring, the honey locust should ideally be pruned in early to mid-summer, after blooming has finished, to prevent excessive bleeding of sap.