Cypress Canker Disease on Italian Cypress
Canker on Italian cypress tree is similar to the appearance of canker on any other species of cypress. Cracks in the bark or wounds become infected with spores of the fungus (Seiridium cardinale) that causes cypress canker and then these cracks ooze sap. Dark sunken cancers, like cracks are found on branches. Resin flows copiously from these sunken areas. Small black spots may be found on some of these cankers. Entire branches or portions of branches wilt and die back. In severe cases sunken, oozing areas appear on the trunk of the tree. If the cankers girdle the tree, then the whole tree dies and should be removed as soon as possible so it doesn’t infect other trees.
There is no known cure for canker disease. Cut out infected branches or portions of branches, dipping tools in alcohol between cuts. Do all you can to improve the health of the tree. Spraying cankers with a natural fungicide like Serenade® might help but I don’t know that for a fact. Increasing the health of a tree can help the trees to throw off canker. I have several Monterey cypress trees (Cupressus macrocarpa) on my property and they have been able to withstand attacks for years because I keep them clean and they make enough sap to ward off beetles and canker. Cleaning out an Italian cypress is not an option, however, because of their shape. I also have several of these and luckily they have not succumbed to canker. Smoke from the wildfires actually helped many trees in my area because it fed them and the robust health they gained helped them toss of beetles and canker.
Round rough growths on cypress trees are not a sign of canker disease. If rough round growths occur on the bark of the trunk of a cypress tree, these likely are immature, undeveloped seed pods that grew in the early life of the tree at the base of a young branch and developed on the trunk of a tree after the branch was gone. They result from stress in the early life of a cypress tree and sometimes persist on the bark of the mature tree where there was once a knot hole (base of branch, now covered over with mature bark.) If these round shapes occur on branches, they are just the cones of the cypress. If there is a whole line of cypress trees and one tree has many more cones than any other in the row this is a sign the tree is under some kind of stress, perhaps lack of water, perhaps some damage to roots. When conifers fear they are going to die they grow an inordinate number of cones.They put all their energy into making cones and seeds in order to assure survival of the species. But Italian cypress always bear quite a lot of cones. If too many, their weight sometimes pulls the branch away from the rest of the foliage and should be wired back in. I have seen some large Italian cypress pruned so that the entire exterior is smooth and even, but this was in a very expensively maintained landscape. Usually all that is necessary is to tie or wire the branch back in place. Clipping off the heavy cones can help, but the tree might simply replace them.