Prunus shirotae (Mt Fuji) Brown Leaf Problems

Discussion in 'Fruit and Nut Trees' started by ken davey, Jan 31, 2008.

  1. ken davey

    ken davey Member

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    Good day folks! I have just found this site and am excited to try to find out if there is an answer to a disappointment we are experiencing with our beautiful Mt Fuji tree.
    3-4 years ago leaves began to wither in early summer. The tree is about 13 years old and stands 18-20 feet tall. The flower production seems to have gone down in that time as well. Although the tree produces new leaves, the overall effect with the brown dry leaves still hanging on is disappointing. It is now January and many of last year's leaves are still hanging on! I examined the tree this morning and find many of the smaller branches/twigs have withered and died although the majority look smooth and viable. The new flower buds are beginning to swell slightly now.
    Any help with this would be appreciated as this tree serves as a backdrop to the centre of the garden.
     
  2. 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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    It sounds like your tree has a brown rot problem. This is a fungus disease commonly found on cherries that can be caused by a couple of different Monilinia species. Typically the disease affects the flowers, blighting them before they have a chance to fall naturally and causing small lesions near the tips of twigs and branches. One of the primary symptoms is shrivelled flowers that do not abscise, but leaves can also be similarly affected.

    Pruning out the affected twigs may be an effective control, but pruning is generally problematic on cherries for a number of reasons. Pruning should only be undertaken when the risk of infection by brown rot fungi and other pathogens, such as Pseudomonas syringae (the bacteria that causes bacterial canker) is low; i.e., during extended dry weather in June and July. Earlier pruning, even during dry weather, may cause bark tearing, which is messy and does not contribute to wound healing. Late pruning (after mid July) can encourage late regrowth that may not harden-off adequately before cold weather arrives. It is important to disinfect your tools between cuts and after pruning.

    Pruning also usually looks bad in a cherry. Branch tip removal generally encourages regrowth that does not follow the natural line of the branch. Thinning (removal of a branch at its origin) is often a better approach in terms of maintaining the overall tree shape, but this may result in more tissue removal than is necessary. Make sure that infected material is not chipped or composted, but taken to a landfill or burned (although proper, industrial composting methods are probably adequate for destroying infective material).

    Finally, cherries require good air circulation, full sunshine and freedom from drips. Overhanging branches or structures of any kind will cause drips, which in turn can spread both fungal spores and bacteria. Some people get good results using "fixed copper" and "copper complex" sprays, both of which have fungicidal and bactericidal properties) as dormant sprays in winter.
     
  3. ken davey

    ken davey Member

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    Thankyou so much for the information on my problem tree. I am going to spray it as you suggest and carefully prune out only the obviously dead twigs. A huge weeping willow which was very near to it has voluntarily fallen down recently, giving the cherry much more air and light which should improve the circulation situation. Thanks again!
    Ken
     

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