Hello; i have 8 fairly large; huge for this area Arba vitaes. Without taking a scientific measurement am guessing the range of around 25 feet tall. Give or take on the measurement. The symptoms an oily drip or bleed from the needles. Most of the time in this area that would say to me aphids. Do You guys know of any other conditions that would cause this???? What will be the best spray to combat this problem????