Insect and tree disease management is an integral part of tree health care. When left unchecked, insects and fungal pathogens can cause irreparable damage to trees. Insects, fungi, and bacteria can cause various health problems and diseases in trees that range in severity. Sometimes the effects can be moderate, such as early defoliation and sometimes they can be severe, leading to tree mortality. Diseased trees can also be a liability to property owners and municipalities when factors such as decay in stems, roots or branches lead to whole are partial tree failure.
Assessing tree health to determine if tree decline is caused by abiotic environmental factors (drought, sun scorch, chemicals, or mechanical injury) or biotic pathogens (insects, bacteria, or fungi) takes a thorough and multifaceted approach.