Controlling suckers in woody plants in the nursery can be time consuming by hand. There is a chemical option that could also be used in large landscapes. The following is more information.
We have had several questions on what materials to use to burn back sucker shoots on nursery plants. The wet season has resulted in a proliferation of sucker shoots. First off, do not try to use glyphopate to burn back sucker shoots. This will translocate into the plant and will cause bark splitting and possible dieback of the plant. Pelargonic acid sold as the product Scythe from Dow AgroSciences Company, can be used to burn back sucker shoots Avoid using this material on young trees with green bark. The material is applied to the sucker shoots before they become woody. The percent used is between 5 and 7%. The 5% rate is 2 quarts in 10 gallons of water. The 7% rate is 2 3/4 quarts in 10 gallons of water.
Information from the University of Maryland TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers