Tree FAQ http://www.treeboss.net/FAQ-about-trees.htm Frequently asked questions about trees. en-us TreeBoss.net How often do you recommend having the following trees professionally sprayed? http://www.treeboss.net/FAQ-about-trees.htm#How_often_do_you_recommend_having_the_following_trees_professionally_sprayed The trees are maple, birch, plum, and locust.