Deep brown spots on Bosc pears and leaves - what is it and what can we do? - Ask Extension
Hello,
Our Bosc pear trees have something affecting the pears and the leaves. The pears have areas that look sort of like they have scabs. Slightly r...
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Deep brown spots on Bosc pears and leaves - what is it and what can we do? #840212
Asked July 12, 2023, 12:47 AM EDT
Hello,
Our Bosc pear trees have something affecting the pears and the leaves. The pears have areas that look sort of like they have scabs. Slightly raised, rough areas that are brown. Only parts of the pears are affected, generally 10% of each pear or even less. And not all pears are affected, perhaps 50% of the pears or less. Those that have the brown areas on them seem mostly to be in more shaded spots on the trees. The leaves also have brown spots, areas and some are completely brown. Again, not all are affected. Perhaps 10% of the leaves are affected. We sprayed with copper in January and a systemic antifungal in May. We have removed the affected leaves. We have other fruit trees including a Bartlett pear and none of them seem to be affected.
We would love to know what you think it is, is there anything we can do about it?
In Corvallis. Thank you for your help!
Benton County Oregon
Expert Response
Thanks for contacting ask extension with your pear question. I believe you are dealing with a fungal or bacterial disease. To help me with the diagnosis I need a little more information.
1. Did you see similar symptoms on the leaves last year?
2. Have you seen the russeting on the fruit in past years? (If yes, did it impact the fruit flesh or just the skin?)
3. Do you see any cankers on the tree?
4. Any sign of bacterial ooze?
5. Did any of your blossoms show signs of infection? Did they shrivel and die?
6. Re: Brown spots on fruit: Did they start off brown or were they olive-black and then turned to brown.
7. Did you see olive-black spots on twigs?
8.Do the infected leaves turn yellow and drop off the tree?
Looking forward to hearing back from you.
1. Did you see similar symptoms on the leaves last year?
2. Have you seen the russeting on the fruit in past years? (If yes, did it impact the fruit flesh or just the skin?)
3. Do you see any cankers on the tree?
4. Any sign of bacterial ooze?
5. Did any of your blossoms show signs of infection? Did they shrivel and die?
6. Re: Brown spots on fruit: Did they start off brown or were they olive-black and then turned to brown.
7. Did you see olive-black spots on twigs?
8.Do the infected leaves turn yellow and drop off the tree?
Looking forward to hearing back from you.
Hi Deb,
Ok, great. Here are the answers to your questions. This is only our second year living with these trees so I’m afraid we don’t have a lot to go on. Hope this helps and thank you!
- Did you see similar symptoms on the leaves last year? Not that we were aware of.
- Have you seen the russeting on the fruit in past years? (If yes, did it impact the fruit flesh or just the skin?) If it was there last year we did not notice it. The fruit was affected with codling moth and I do not know if it was also affected by anything else.
3. Do you see any cankers on the tree? No
4. Any sign of bacterial ooze? No
5. Did any of your blossoms show signs of infection? Did they shrivel and die? Not that we noticed but I could use education on this I am not sure what this would look like since all blossoms fall off?
6. Re: Brown spots on fruit: Did they start off brown or were they olive-black and then turned to brown. I believe they may have yes.
7. Did you see olive-black spots on twigs? Not that I am aware of
8.Do the infected leaves turn yellow and drop off the tree? No, the brown just progressed to nearly black. They did not fall off even when fully dark brown/black but we removed them.
Thanks again!
Jennifer
On Jul 12, 2023, at 1:30 PM, Ask Extension <<personal data hidden>> wrote:
Thanks for answering my first round of questions. I have just a couple more.
1. Your picture of the damaged leaves (IMG-1050) looks to me like the branch spurs are blackened (although it could be just a shadow).
When I asked about blossom showing damage, I should have asked about the stems that the blossoms were attached to. I think I see a black and shriveled blossom twig in the picture.
Can you confirm if this is what I'm actually seeing?
2. And lastly. Would you cut into one of pear fruits to see if the russeting is on the skin only or if it has penetrated into the flesh?
Sorry for all the questions!
1. Your picture of the damaged leaves (IMG-1050) looks to me like the branch spurs are blackened (although it could be just a shadow).
When I asked about blossom showing damage, I should have asked about the stems that the blossoms were attached to. I think I see a black and shriveled blossom twig in the picture.
Can you confirm if this is what I'm actually seeing?
2. And lastly. Would you cut into one of pear fruits to see if the russeting is on the skin only or if it has penetrated into the flesh?
Sorry for all the questions!
Hi Deb,
No worries about your questions, keep them coming. Just want to figure this out.
I don’t think the branch spurs are blackened but the buds at the tips seem very dark
As far as the stems on the blossoms we did not notice any damage on those stems when they were blooming. I am not exactly sure what a blossom twig is. Is that like a fruit spur that did not produce fruit? I don’t really see any of them shriveled or blackened but I may not be looking in the right place.
The cut pear looks like the russet on the outside does not affect the inside. See the pictures please.
Sorry I don’t seem to be able to really answer your questions well. I hope this info helps you solve the mystery anyway.
Thank you,
Jennifer
On Jul 13, 2023, at 6:19 PM, Ask Extension <<personal data hidden>> wrote:
Hi again!
Can you rub off the black stuff on the leaves?
Are the leaves sticky (honeydew?)
Hope you are staying cool during this hot spell.
Can you rub off the black stuff on the leaves?
Are the leaves sticky (honeydew?)
Hope you are staying cool during this hot spell.
Hello Deb,
No, we definitely cannot rub off the black of the leaves. The affected leaves have partially or fully changed color to black. The blackened areas of the leaves goes fully through the leaf. If you turn them over the underside looks exactly the same as the topside. And the leaves have no stickiness to them.
Thanks again,
Jennifer
On Jul 15, 2023, at 1:38 PM, Ask Extension <<personal data hidden>> wrote:
Hello Jennifer,
Thank you for all your patience with all of our questions. This one is a stumper! We think that there may be more than one thing going on here, in that what's affecting the leaves may be separate from what's going on with the fruit.
Bottom line up front:
We can not identify precisely what is going on with your pear tree. Our recommendation is to keep picking off and destroying the affected leaves. Monitor the tree for signs of insects, cankers or twig die back. Look for little bumps on the leaves that might indicate mites or other sucking insects.
Possible causes:
Fruit Russeting;
The spots on the fruit looks a little like russeting, which can be a symptom of a number of different causes. Russeting can occur from cold, wet weather, insect activity, or some types of fungi. Given that the interior of the fruit does not seem to be affected, and that the damage is not extensive you may wish to monitor for insect activity on your pear trees and see how things develop. Russeting does not impact the flavor, texture of shelf life of the fruit.
Leaf Spots:
The leaves are suggestive of early stage Fire Blight. Not all of the symptoms of Fire Blight are present on your tree so we can not say for certain. Fire Blight is a serious problem for fruit trees, and is worth knowing about so you can watch for other signs. There are not many good options for dealing with it other than vigilance in pruning out affected wood and good sanitation. We've provided more information about Fire Blight below. Fire Blight is a bacterial disease. This WSU publication has some excellent images showing what to watch for.
https://treefruit.wsu.edu/crop-protection/disease-management/fire-blight/
Again, we're just not sure. You may have to just continue to monitor and keep careful track of what's going on with your trees as the year progresses, and documenting anything with photographs and notes that seems off. Keep watch of your blossom development next year.
Again, this is a really hard one! Please keep us posted if you see any further developments that may help us identify the underlying issues.
Deb K & Jennifer G
Thank you for all your patience with all of our questions. This one is a stumper! We think that there may be more than one thing going on here, in that what's affecting the leaves may be separate from what's going on with the fruit.
Bottom line up front:
We can not identify precisely what is going on with your pear tree. Our recommendation is to keep picking off and destroying the affected leaves. Monitor the tree for signs of insects, cankers or twig die back. Look for little bumps on the leaves that might indicate mites or other sucking insects.
Possible causes:
Fruit Russeting;
The spots on the fruit looks a little like russeting, which can be a symptom of a number of different causes. Russeting can occur from cold, wet weather, insect activity, or some types of fungi. Given that the interior of the fruit does not seem to be affected, and that the damage is not extensive you may wish to monitor for insect activity on your pear trees and see how things develop. Russeting does not impact the flavor, texture of shelf life of the fruit.
Leaf Spots:
The leaves are suggestive of early stage Fire Blight. Not all of the symptoms of Fire Blight are present on your tree so we can not say for certain. Fire Blight is a serious problem for fruit trees, and is worth knowing about so you can watch for other signs. There are not many good options for dealing with it other than vigilance in pruning out affected wood and good sanitation. We've provided more information about Fire Blight below. Fire Blight is a bacterial disease. This WSU publication has some excellent images showing what to watch for.
https://treefruit.wsu.edu/crop-protection/disease-management/fire-blight/
Again, we're just not sure. You may have to just continue to monitor and keep careful track of what's going on with your trees as the year progresses, and documenting anything with photographs and notes that seems off. Keep watch of your blossom development next year.
Again, this is a really hard one! Please keep us posted if you see any further developments that may help us identify the underlying issues.
Deb K & Jennifer G
