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.

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  1. planted 15 cypress in SC 3 yrs. ago. canker appeared in most of the 15. lost only 2.
    have sprayed and doused roots with diluted mixture of cleary 3336f & daconil for past year. followed Cleary tech support advice.
    all signs of canker gone, but best change made was adding a drip irrigation system last spring. all growing tall & very green. was told it’s important to make a fungicide cocktail b/c canker can develop resistance to just one.

    • Thank you for your comment, but Daconil and Cleary 3336F Fungicide are dangerous chemicals that are long-lasting in the environment. They have no place in an organic garden. Cleary 3336F Fungicide is not permitted in the state of California where I live and which has stronger regulations against destructive and dangerous chemicals than many other states. Cleary 3336F is also systemic (Daconil is not systemic.) Long lasting pesticides and systemic products often enter groundwater even when early tests show they don’t. (Roundup is a good example of a chemical product—in the case of Roundup, a systemic weed killer—that for many years was thought to be harmless and even short-lived in the environment but now traces of it have been found in ground water.) Thus I cannot speak strongly enough against the use of chemicals in home gardens and even on farms. I myself grew up on an organic farm and my family made a successful business of it.

      The advice that I give gardeners on this blog is confined to organic methods of gardening, including pest and disease controls. In the long run you can grow an amazingly healthy and disease-free garden by following the organic way. Organic practices free up the natural disease controls—beneficial fungi that reside in the soil itself. Left to their own devices, these beneficial fungi can control the “bad guys”, but all fungi, both good and bad, are killed by chemical pesticides and fungicides. Thus, when you use chemical fungicides you kill off the beneficial fungicides that nature provides as natural disease controls in the soil. Thus I would not recommend that anyone use Daconil or Cleary 3336F Fungicide.

      Organic gardeners do not use chemical disease controls or pest controls and they avoid using chemical fertilizers also. Our desire is to put the health of our families, our pets, and our planet ahead of any perceived benefit of using a disease control or pest control that may offer a quick solution to a problem but is also a dangerous poison that can get into ground water, and poison people, animals, fish, or beneficial insects and arachnids. We prefer to take the safe route and use only organic controls, even if it means losing a few plants en route.

      Organic gardeners have weighed the balance and decided that it’s better to be on the safe side and overcome plant problems in organic ways. We feel this is far better than getting cancer ourselves or contributing to a situation that is giving cancer to little children in our country. A hundred years ago when none of these modern chemicals existed, our little kids weren’t getting cancer, losing their hair and dying from leukemia and a host of other ills. Following the organic way of gardening may mean avoiding growing certain plants that are not well adapted to the environment in which we are trying to grow them, but organic gardeners feel this is a small price to pay in return for doing the right thing for our planet, the future health of the human race and the well-being of animals and nature. It is many years since Rachel Carson’s book “Silent Spring” was first published, but its message still has not sunk in. Rachel Carson was not just talking about DDT, she was sounding an alarm against petrochemicals as a whole and many of the problems she saw ahead are now happening.

      • Is there any type of cypress that is canker-resistant, nice looking and available in Southern California so that I do not need to use Daconil and Cleary 3336F Fungicide?

        I have a fence of more than twenty trees of Italian Cypress which are dying, one after another. Taking all of them out at once is not an option.

        • Hi, Mario.

          I’m in Northern California. I have a few older Italian cypresses and many more in my neighborhood. All of them are doing well. However, I am still looking for another privacy and windbreaking plant which is canker resistant. Did you have luck finding another tree?


          • Have you considered Thuja ‘Green Giant’? Though Thuja plicata can also fall prey to cypress canker, it is further down the list of susceptible plants and also this variety is a hybrid cross with T. standishii and T. plicata and thus might be more resistant. But since none of the Italian cypress trees in your area seem to be afflicted and your trees are okay now, until the problem arises why worry? Italian cypress growing in cooler climates seem to be doing better than those in the hot interior. I have three Italian cypress trees in my garden. I have them cut the Italian way (lower branches removed), they are all okay now. There really is no substitute that does the same thing, so if they die I will go for another look entirely. If I were growing these as a screen I would fill in blank spaces with another tall screening plant, that is trouble free and can be clipped, such as Podocarpus gracilior, or I might use an evergreen climber, such as star jasmine. In Hollywood I notice that many of the old eugenia hedges have grown very tall and are intertwined with tropical vines. Mixed hedges are not all bad and you often see them in old Japanese gardens and in England, where one thinks of the gardeners as being such purists. In Japan I even saw small-leaved holly mixed with conifers and clipped like a hedge.

  2. Are these cankers/pods that develop on the trunk of the cypress toxic or harmful if you touch them or they open up and get on you? Just asking if anyone knows
    Thank you

    • No. Cypress canker is non-toxic (i.e. to human beings), so don’t worry about touching the tree other than not to get sticky sap on your skin or your clothes.

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