Question

The canker  

Inside of canker   I am in the Virginia Beach Oceanfront area and have a beautiful magnolia that flowers pink blooms in the spring. I have recently lost two large limbs. I noticed cankers in the bark...they are under the top layer...and in several locations. I have enclosed pictures...do you know how to treat this? I don't want to loose the whole tree:(. I can send more pictures if needed. Thank you.

Answer
 Sounds like a disease called hypoxolyn canker. Hypoxylon cankers are prevalent and highly visible disease problems affecting oaks and other hardwoods. Hypoxylon spp. are not considered aggressive killers. Instead, they are usually secondary in that they take advantage of trees suffering from any number of injuries of stresses. Hypoxylon cankers are often the finishing blow to oaks suffering from water stress, root disease, soil compaction, construction damage or other, related injuries.

Trees with extensive Hypoxylon infections are usually beyond repair. Removal of severely infected trees to reduce local sources of inoculum (i.e., infectious spores) is recommended. Careful pruning of branches that have localized infections should help prevent advancement of the fungus within the infected trees. Prevention of infections through avoiding wounds, root damage, etc., and providing adequate moisture via irrigation to susceptible trees during prolonged periods of dry weather is the best method of control. The presence of Hypoxylon cankers is usually an indicator of severe stress and often a warning to take precautions to reduce stresses (if they can be identified and reduced) affecting nearby trees of the same species.
Watering during dry periods with 1 inch of water (place a pan under the tree and turn the sprinkler on and when the pan has 1 inch of water in it stop). Fertilize the trees with 10-10-10 fertilizer at the rate of 1 lb. per inch of trunk diameter scattered around the tree and watered in good. Apply just before a rain event and you will not need to water. This should help the trees regain their health. I would fertilize now and again in the spring.