Sanitation is one of the most important and first lines of defense in preventing insects and disease such as Apple Scab in the landscape. The simple act of cleaning up fallen leaves from an apple, crabapple or pear tree can immensely reduce the severity of infection the following spring. Once you have raked them up, dispose of them off-site as the spores can travel some distance by wind. Even infected leaves from nearby volunteer or undesirable trees should be cleaned up.