He might spray the tree with pesticide or fungicide or inject medicine into its bark. After treatment, he might prescribe a special watering or fertilizer regimen, as he did in the case of the dying Arizona eucalyptuses. Often, he cuts diseased or infested branches off the tree to save the others, a process called pruning. He also prunes branches that rub together and those that are not well supported by the rest of the tree. Pruning a tree correctly takes skill.
Arborists climb onto a tree s branches using ropes and hanging seats called climbing saddles.
They carefully remove branches with chainsaws, shears, and tiny clippers. If a branch is diseased, arborists sometimes dip their tools in disinfectant before cutting another branch to prevent the spread of infection. Jeff, like all arborists, uses mathematics to analyze a tree s structure before he decides which branches to cut. We measure the tree s circumference, and we can figure out a tree s height without climbing it. Some arborists use computer programs to calculate the forces and weights within a tree.