Source(s): Gary R Peiffer
Bot Canker (Botryosphaeria dothidea, B. obtusa, Sphaeropsis, Macrophoma)
Infected branches on Leyland cypress are a bright rust color most often visible in spring and fall. The bot organism attacks sites with wounds from pruning, mechanical damage, freeze cracks, etc. or natural opening (lenticels) following a stress event such as drought. A sunken or flattened stem canker develops at the infection site and may ooze sap (gummosis). Eventually it may encircle the branch or stem killing all foliage above the site. It has a wide host range including Leyland cypress, fruit and shade trees and vines.
Prune diseased branches six (6) inches below the infected area. Water and fertilize plants appropriately to avoid stress and promote good growth. Protect plants from injury. Avoid planting too close together (plants need to be far enough apart to allow for good air circulation). No fungicides are effective once infection has occurred. A protective fungicide application when an injury occurs may reduce the possibility of infection.
Resource(s): Common Landscape Diseases In Georgia
Center Publication Number: 53