I got my trees treated for pests/diseases last year. Do I need to get them treated again this year?

It depends on your plant health care program, the problem at hand, and the prescribed treatment that was employed. Some applications may need to be reapplied each year, like treatments for aphids, while others like Dutch Elm can be every three. Otherwise, annual inspections are recommended, and your arborist will advise the best health care schedule for your landscape.