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Fungus and cancers on fruit trees #757441

Asked June 21, 2021, 12:01 PM EDT

Hello, I have about 20 fruit trees on my property and 4 of them look to be infected but a seeping, red wet cancerous growth in the bark that has killed one of my peach trees. It looks like if the growth gets all the way around the trunk or a limb it will kill that portion. I need to safely remove a dead tree and dead limb without spreading the infection and treat the other cancers if possible to save the other 3 trees. Do you have any recommendations on removal and treatment? Thank you, Valerie Reed

Larimer County Colorado

Expert Response

Hi Valerie,

Based on your description alone, my best guess is this is Cytospora, which is a type of fungus and very common on fruit trees. It tends to affect stressed trees (those that are suffering from drought, improper pruning, planting issues, etc.).

https://extension.colostate.edu/topic-areas/yard-garden/cytospora-canker-2-937/

Yes, you can remove the cankered limbs and throw them in the trash (do not compost). Between each cut, sanitize your pruning tools with 1:10 diluted bleach or Lysol. And the most important thing would be to improve the overall cultural health. Water appropriately; water in the fall and winter; mulch the base of the trees (keeping it away from the trunk); and make proper pruning cuts. 

Alison O'Connor, PhD Replied June 21, 2021, 5:06 PM EDT
Thank you, Alison!
 Is there a treatment for the affected bark such as a fungicide or wrap to stop the spread?
Does it get in the ground so that I cannot replace a dead tree until the ground has been treated?
I heard you should scrape the infected bark. Do I need to take any special precautions with the gooey stuff? Should I only scrape the dry stuff? Can I do this when the weather is damp and rainy like this weekend is supposed to be?
Thank you so much for your help!!
 Valerie

On Mon, Jun 21, 2021 at 3:06 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied July 27, 2021, 9:48 AM EDT

Hi Valerie,

The best way to reduce spread is to reduce overall tree stress--this means making proper pruning cuts, adding mulch, and watering properly. I wouldn't advise you scrape away any of the tissue because you can do more harm than good (and damage the cambium). 

If the trees die, you can replace them in the same spot. This is not a soil-borne fungus. Again, if it is cytospora (which I cannot confirm because I haven't seen photos), this is a stress-related disease. So do your best to eliminate stress :)

Alison O'Connor, PhD Replied July 27, 2021, 10:21 AM EDT

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