help!!..ornamental cherry anthacnose..

Discussion in 'Woody Plants' started by murphy, Aug 6, 2003.

  1. murphy

    murphy Member

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    ..i have three ornamental cherry trees that i think have anthracnose...they bloom beautifully in the spring, leaves begin to grow, and shortly thereafter, the leaves begin to deform and show dark brown spots - almost burnt...and the leaves begin to drop....by this time of the year, they are sad specimens..i am reluctant to cut them down especially since one grows up thru my deck offering shade and a place for my bird feeders...treatment of this disease doesnt sound too successful....i'd appreciate some *unbiased* opinions on what if anything can be done for this condition...

    thanks!

    murphy, delighted to have found this site as a new resource!
     
  2. jimmyq

    jimmyq Well-Known Member 10 Years

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    Other issues the trees may have could be;

    Blossom and shoot blight, a common reaction with damp weather after blossoms finish in spring, twig ends and leaves as well as spent flowers all turn brown and may shrivel and dry on the plant.

    Shot hole fungus can also be a problem, causing small brown spots on the leaves which gradually dry , turn brown and then fall out or get blown out by wind leaving holes in the leaves. When you stand at the base of a tree with this problem you can look up through the canopy and it will look as though someone has pointed their shotgun up and taken a few rounds out of the tree, hence the name.

    I would say the best course of action is to get the problem correctly identified if possible, take some pictures or some plant parts to a local nursery or have a qualified professional come out to have a look.
     
  3. murphy

    murphy Member

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    thanks for those thoughts....taking in a sample of what is left of the leaves is a good idea....

    ....a neighbour has suggested the trees have come to the end of their life span..i'm guessing they are about 20 years old....is this possible...?...i dont think that would be reflected in such damaged leaves, imho....he said the bark was not smooth and was not able to conduct nutrients up to the leaves?...i am in denial over this diagnosis as i dont want to lose them!

    murphy
     
  4. Douglas Justice

    Douglas Justice Well-Known Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    Yes, pictures would be useful; however, the symptoms you describe sound very much like those caused by bacterial blight (Pseudomonas syringae) and brown rot (Monilinia fruticola and/or M. laxa), both exceedingly common diseases of cherries in wetter parts of the Pacific Northwest. As the two produce overlaping symptoms in cherries, they are often referred to interchangeably (they are nevertheless very different organisms -- one is bacterial, the other fungal). The diseases are particularly common on some popular ornamental cultivars, including nearly all those derived from Prunus subhirtella (spring cherry) and P. avium (includes the mazzard as well as the sweet cherries). Cultivars in the Sato Zakura Group (the village cherries -- a group that includes many of the most common large-flowered "flowering cherries") vary in their susceptibility.

    Unfortunately, both diseases are difficult to control on older plants. Cankers severely weaken stems and are a perennial source of reinfecting inoculum. Judicious pruning to remove these cankers often does not help; besides disfiguring the trees, open wounds on cherries are common sites for infection (often, the larger the cut, the bigger the problem). Compounding the blight and rot problems, virus diseases in the tree, which are untreatable in infected existing plants, may contribute to the decline in overall health and vigour. The application of copper and sulphur sprays is sometimes recommended (both materials acceptable to the "organic" gardening community), but the frequency of application and overall effort required probably would not warrant trying, except with exceptionally valuable specimens.

    Preventing infection is difficult. Both bacterial blight and brown rot are spread by rain splashing, pruning tools and insects. The severest infections tend to occur when winters are not cold enough to knock out the overwintering pathogens. Good air circulation is enormously important for the health of the tree, as is full sun exposure and well-drained soil. Virus diseases of cherries are primarily spread by insects. Some are pollen-borne diseases -- and therefore impossible to prevent without completely deflowering the tree annually (which kind of defeats the purpose) -- but other viruses may be vectored by aphids or their relatives or other arthropod pests.

    Once trees are in a weakened state, cherry bark tortrix is a common visitor. This insect lays eggs in fissures on the trunk and major limbs, usually at a graft union or around a canker, whereupon the hatching larvae tunnel to the cambium and create extensive galleries. Identification of cherry bark tortrix itself is difficult (the adult is an small insignificant moth), but the presence of the larvae is shown by the small piles of orange coloured sawdust pushed out of tiny holes in the bark. Trees at this stage of decline are probably best removed entirely.

    With severely affected trees, it is probably sensible to either replace the tree with a species more appropriate to the site (i.e., a completely different plant), or if the conditions are suitable, a cherry more resistant to the common problems (such as the daybreak cherry, P. yedoensis 'Akebono').
     
  5. murphy

    murphy Member

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    ....thank you for taking the time to make such a detailed and understandable reply, douglas.....it sounds like you have hit the nail on the head, and the fact that we have had several mild winters would validate lack of kill due to cold temps....sounds like i will have to think about how i am going to replace the tree growing in the middle of my deck....the other two are no problem to get out and i may not even replace those....

    ...once again, i am absolutely delighted to have stumbled upon this forum and look forward to reading more of the discussions already here..

    thanks to all that have offered insight into my problem..

    murphy
     

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