How to Recognize, Manage and Prevent Leaf Spots (Fungus) on Cherry Leaves

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Get Rid of Downed Trees

  • I guess you could say "beware of fallen cherry trees!"
  • Spores from the fungus Blumeriella jaapii overwinter in those pesky, downed trees and in the spring, rain and wind will be glad to carry them to your cherry trees causing cherry leaf spots. The real problem is that this type of fungus infection will decrease the nutrition available to your cherry tree and the result is a reduced crop of poor-quality cherries. Sweet and sour cherries are affected, as this fungus does not discriminate.

Recognizing Cherry Leaf Spot Fungus

  • This fungus will appear in all zones where cherries are grown. The fungus begins with tiny, brown-purplish spots on the upper surface of the cherry leaves. As these spots get bigger, the leaf tissue dies and produces a toxin that causes the leaves to become yellowish, and defoliation is produced in the infected leaves.
  • Spots appearing on the actual fruit and leaf stems are a sign of a severe infection. In warm, wet weather, small white specks appear on the underside of the leaf. They will become raised and become creamy-colored bumps which are directly beneath the colored spots of the topside of the leaves.
  • The result is that the centers may separate from the healthy plant tissue by drying, leaving a small hole. The effect of defoliation before the cherries ripen is a decrease in the fruit yield. The remaining fruit will be mushy, soft and watery.

Preventing Cherry Leaf Spot Fungus

  • It is very important to choose the correct type of cherry tree for your climate (and soil). There are no cherry trees that are immune to this fungus but some varieties, such as Meteor and Northside are partially resistant.
  • Sour cherries appear to be less resistant than sweet cherries. In order to prevent this nasty fungus from ruining your crop, you should learn to water and fertilize your trees properly. Pruning will improve air circulation, which in turn, improves fruit quality.

Meteor Cherry Trees are partially resistant to Cherry Leaf Spot fungus, but not totally immune.
Meteor Cherry Trees are partially resistant to Cherry Leaf Spot fungus, but not totally immune.

Management of Cherry Leaf Spots

  • If cherry leaf spots are infecting your current crop of cherries, there is no way to completely manage the damage. If you begin when the petals fall, it is possible to achieve partial management, by spraying with a fungicide containing captan, sulfur or chlorothalonil. Be sure to read the manufacturer's instructions on any fungicide and follow them closely. It is possible to do more harm than good when it comes to fungicides.
  • DON'T use the fallen leaves in your mulch. Rake them up and get them out of there!
  • Pruning plants will increase air circulation.

If you are curious, this chart shows the disease cycle of cherry leaf spots.  Great job by WVU.
If you are curious, this chart shows the disease cycle of cherry leaf spots. Great job by WVU. | Source

Pointers

  1. Severe leaf drop will cause cherry trees to weaken and they can be damaged further by the cold. The result is a lower fruit yield.
  2. Defoliation predisposes the cherry tree to damage from sunscald.
  3. Older leaves are less susceptible to cherry leaf spots.

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Comments 2 comments

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Casey White 4 years ago from United States Author

You are so right, Cat. Thanks!


cat on a soapbox profile image

cat on a soapbox 4 years ago from Los Angeles

Good advice. Disnfecting pruners in a mid bleach/water solution is also important in preventing re-infection.

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