infection on fruits of serviceberry tree + growths on black cherry tree - Ask Extension
Hi:
I planted a black cherry tree about 3 decades ago to provide food for wildlife, even though I knew that cherry trees gets diseases.
Two years a...
Knowledgebase
infection on fruits of serviceberry tree + growths on black cherry tree #872400
Asked June 10, 2024, 11:43 AM EDT
Hi:
I planted a black cherry tree about 3 decades ago to provide food for wildlife, even though I knew that cherry trees gets diseases.
Two years ago I planted a new Amelanchier canadensis (serviceberry) to replace the one that had died in order to provide fruits for the birds. Just a couple of days ago I was shocked to see that all the fruits on the Amelanchier had growths on them which probably make them unfit for consumption. I suspect the growth is caused by a fungus. The first photo is from the Amelanchier and the next two are from the black cherry. My questions are the same for both trees; what caused these conditions and more importantly, what if anything should be done now or later to prevent the problems in the future. Please note that with extensive straight-species native perennials in my gardens, I do not spray anything that can harm the other beneficial pollinators and other invertebrates. Allow me to thank you now in advance for your answers which are always so helpful.
Carroll County Maryland
Expert Response
The symptoms on the Amelanchier are due to rust, a very, very common fungus that affects various rose-family tree species in our region. (To the best of our knowledge, this is a native fungus.) Several species of rust, all with similar symptoms, can infect Amelanchier, such as Cedar-apple Rust or Cedar-quince Rust. Neither can be treated once spores manifest on the Amelanchier, because those spores are infecting our wild Eastern Redcedar (Juniperus virginiana). Next spring, spores emerging from Redcedar infections will be wind-blown onto hosts like Amelanchier, completing the cycle.
While a rust infection can render most fruits on a tree inedible for people and birds, the plant's flowers and foliage still supports pollinators and other wildlife, and birds have evolved to having to shift foraging behaviors to account for natural "crop failures" such as this. (Many songbirds consume way more insects and spiders than berries in summer anyway, especially as they feed nestlings.)
There are no non-chemical controls for rust diseases, short of the impossible task of removing all junipers in a several-mile radius. That said, if you suspect they're blowing in from a certain direction, you could try planting a windbreak of sorts to intercept airborne spores. We would not recommend the use of a fungicide even when one would be effective (early in spring as spores are moving off of infected Juniper hosts), for the reasons you cite -- potential ecological impacts and the risk to pollinators, since sprays would likely need to coincide with Amelanchier blooms. Fungicides are also not foolproof anyway, and can fail to protect a plant if the weather does not cooperate with a spray schedule (since often multiple repeat applications are needed).
The symptom on the cherry is harder to diagnose (though familiar), but is similarly not a concern nor a threat to the plant's overall health. It might be a witches-bloom (mutated growth that tends to be dwarfed and congested), which can be caused by a variety of naturally-occurring factors, coupled with Brown Rot or a similar infection, or it could be Brown Rot by itself on flowering branch spurs. As with the above, no treatment is possible at this point, nor is a fungicide recommended.
Plant disease spread and severity can be highly weather-dependent, prevalent in years with wet springs and subdued in drier years. It can also depend on the genetics of the individual plant, which might have a natural inborn resistance to certain pathogens (or not). While cleaning-up and disposing of infected debris can help reduce the spore presence around vulnerable hosts, it's not a foolproof measure (especially with fungi having an unusual life cycle like rust) and it's not practical for many tree infections given the relative inaccessibility of the symptomatic areas of the canopy. As with the Amelanchier, the cherry will at least still have value to leaf-eating insects, which in turn will still support birds and other wildlife.
Miri
While a rust infection can render most fruits on a tree inedible for people and birds, the plant's flowers and foliage still supports pollinators and other wildlife, and birds have evolved to having to shift foraging behaviors to account for natural "crop failures" such as this. (Many songbirds consume way more insects and spiders than berries in summer anyway, especially as they feed nestlings.)
There are no non-chemical controls for rust diseases, short of the impossible task of removing all junipers in a several-mile radius. That said, if you suspect they're blowing in from a certain direction, you could try planting a windbreak of sorts to intercept airborne spores. We would not recommend the use of a fungicide even when one would be effective (early in spring as spores are moving off of infected Juniper hosts), for the reasons you cite -- potential ecological impacts and the risk to pollinators, since sprays would likely need to coincide with Amelanchier blooms. Fungicides are also not foolproof anyway, and can fail to protect a plant if the weather does not cooperate with a spray schedule (since often multiple repeat applications are needed).
The symptom on the cherry is harder to diagnose (though familiar), but is similarly not a concern nor a threat to the plant's overall health. It might be a witches-bloom (mutated growth that tends to be dwarfed and congested), which can be caused by a variety of naturally-occurring factors, coupled with Brown Rot or a similar infection, or it could be Brown Rot by itself on flowering branch spurs. As with the above, no treatment is possible at this point, nor is a fungicide recommended.
Plant disease spread and severity can be highly weather-dependent, prevalent in years with wet springs and subdued in drier years. It can also depend on the genetics of the individual plant, which might have a natural inborn resistance to certain pathogens (or not). While cleaning-up and disposing of infected debris can help reduce the spore presence around vulnerable hosts, it's not a foolproof measure (especially with fungi having an unusual life cycle like rust) and it's not practical for many tree infections given the relative inaccessibility of the symptomatic areas of the canopy. As with the Amelanchier, the cherry will at least still have value to leaf-eating insects, which in turn will still support birds and other wildlife.
Miri
Hi Miri: I was not expecting an answer so soon. Thanks so much. If I read your reply correctly, I should NOT spray a fungicide on the Amelanchier next spring as a rust preventer. If that is true, then do I assume that the fruits will be infected again next year and each year thereafter?
I originally had an Amelanchier canadensis in the same spot for 20-25 years and its fruits never got rust. During all those years, I had a 140 foot row of Juniperus virginiana (eastern red cedar) of which a few years ago the road dept. cut down 120 feet of trees leaving me with about 4 trees covering about a 20 foot row. And now with a minimum number of Eastern Red Cedar trees, of which I see no rust infection on them, I get rust.
Thanks,
Jim
Hello Jim,
Correct, we're recommending that you not spray a preventative fungicide for rust. In part, this is because such measures aren't always successful, and because fungicides could risk harm to other organisms, including pollinators (particularly in this case as applications would probably need to occur around the time the Amelanchier flowers will be open). Since you'd mentioned that you "do not spray anything that can harm the other beneficial pollinators and other invertebrates," this seemed to be in alignment with your goals of minimizing pesticide use. True, this means that the plant might develop rust infections in the future, though not necessarily extensively every year.
The situation with your prior Amelanchier and Junipers could have been happenstance, in the sense that the prior Amelanchier might have been naturally more resistant (genetic variability being a factor), and the nearby Junipers might not have been infected with rust, but perhaps now unrelated junipers elsewhere in the neighborhood (or within a couple miles, really) that have since grown up happen to have a rust infection now that is disseminating into your area when spores emerge each spring and are carried on the wind. We are not aware of any cultivar of Amelanchier with reliable resistance to rust, though undoubtedly there are individuals in wild populations that develop less rust than others when exposed to the same degree of infection potential.
Maybe that old row of junipers happened to serve as a windblock to rust spores coming from other junipers (spores produced on their stems cannot infect other junipers, only the rose-family host tree), which are now finding an easier path to your new Amelanchier, but we can only guess as to the reason fortunes have changed in that regard.
If you opt to try a fungicide anyway, find a product that lists rust as one of the diseases controlled, and follow all label directions for use carefully. Sprays will need to begin well before symptoms begin on the Amelanchier (junipers are not treated), likely around April or so, depending on when the weather becomes warm and mild (at least for a few days). Re-treatment will need to occur at whatever spray interval the product instructions dictate. Once the spore dispersal period from the juniper host has passed (likely into at least early May), then sprays can cease, because they've either done their job at preventing infection for the year or the threat of new infection is no longer present, since the disease cycle is progressing in the Amelanchier (or whatever rose-family host the spores have found) at that point. Since rust is not fatal to the host plant, that is another reason we generally avoid recommending treatment with a fungicide, since it's more of an eyesore than a threat to plant longevity.
Miri
Correct, we're recommending that you not spray a preventative fungicide for rust. In part, this is because such measures aren't always successful, and because fungicides could risk harm to other organisms, including pollinators (particularly in this case as applications would probably need to occur around the time the Amelanchier flowers will be open). Since you'd mentioned that you "do not spray anything that can harm the other beneficial pollinators and other invertebrates," this seemed to be in alignment with your goals of minimizing pesticide use. True, this means that the plant might develop rust infections in the future, though not necessarily extensively every year.
The situation with your prior Amelanchier and Junipers could have been happenstance, in the sense that the prior Amelanchier might have been naturally more resistant (genetic variability being a factor), and the nearby Junipers might not have been infected with rust, but perhaps now unrelated junipers elsewhere in the neighborhood (or within a couple miles, really) that have since grown up happen to have a rust infection now that is disseminating into your area when spores emerge each spring and are carried on the wind. We are not aware of any cultivar of Amelanchier with reliable resistance to rust, though undoubtedly there are individuals in wild populations that develop less rust than others when exposed to the same degree of infection potential.
Maybe that old row of junipers happened to serve as a windblock to rust spores coming from other junipers (spores produced on their stems cannot infect other junipers, only the rose-family host tree), which are now finding an easier path to your new Amelanchier, but we can only guess as to the reason fortunes have changed in that regard.
If you opt to try a fungicide anyway, find a product that lists rust as one of the diseases controlled, and follow all label directions for use carefully. Sprays will need to begin well before symptoms begin on the Amelanchier (junipers are not treated), likely around April or so, depending on when the weather becomes warm and mild (at least for a few days). Re-treatment will need to occur at whatever spray interval the product instructions dictate. Once the spore dispersal period from the juniper host has passed (likely into at least early May), then sprays can cease, because they've either done their job at preventing infection for the year or the threat of new infection is no longer present, since the disease cycle is progressing in the Amelanchier (or whatever rose-family host the spores have found) at that point. Since rust is not fatal to the host plant, that is another reason we generally avoid recommending treatment with a fungicide, since it's more of an eyesore than a threat to plant longevity.
Miri
Thank you for all the additional information, Miri.
I had not mentioned previously but wish to tell you now that the Amelanchier is only about 6-7 feet tall and about 3-4 feet wide with lots of air space between trunks so perhaps I could very carefully spray it next year. But only if I could in effect, "spot" spray it, with as little amount as possible and without much of the fungicide going beyond the tree. If so, I will read the directions to see if I can use a handheld pump bottle of solution to spray just the flower buds and/or the trunks and branches and/or the surrounding soil under it.
Again, thank you for all your helpful and detailed answers!
Have a good day.
Jim
You're welcome.
One additional note, after we checked with out plant pathologist: If spraying for rust prevention, treatments would probably need to start in April (around the time the Amelanchier buds are breaking dormancy) and continue (at whatever interval the product directs) for a period of about 8-10 weeks, because that's how long spores are moving off of infected junipers and starting new infections. If you intend to consume any of the fruit yourself, make sure the fungicide chosen is labeled for use on edible plants (at least "fruit trees"...it might not list Amelanchier specifically).
Miri
One additional note, after we checked with out plant pathologist: If spraying for rust prevention, treatments would probably need to start in April (around the time the Amelanchier buds are breaking dormancy) and continue (at whatever interval the product directs) for a period of about 8-10 weeks, because that's how long spores are moving off of infected junipers and starting new infections. If you intend to consume any of the fruit yourself, make sure the fungicide chosen is labeled for use on edible plants (at least "fruit trees"...it might not list Amelanchier specifically).
Miri
