Many landscapers design gardens and lawns to provide shade from trees. Despite the best planning, the roots of trees spread out and occasionally send up secondary trees. The placement of these trees can become a nuisance and can present a problem by their presence. To rid your yard or garden of these nuisances, you can poison the trees and remove them when they die off. Herbicides and salt perform well at this task, but salt has the drawback of killing everything that grows in the area and takes many years before anything will grow in that spot again.
Choose a hot day without rain in the forecast to treat your trees. You need time for the treatment to work before dilution occurs by rainfall. If it rains before the herbicide can take full effect, the effectiveness of the treatment will drop drastically.
Fill a spray bottle with undiluted herbicide. Choose a sprayer that has enough power to reach the top of the tree.
Spray the leaves of the tree with the herbicide. The tree will bring the herbicide into its circulatory system and the poison will begin working to kill the tree.
Drill holes into the trunk of the tree and fill them with herbicide. The herbicide will work from the inner core of the tree. The points where the hole breaks through the bark will yield greater access to the circulatory system.