Knowledgebase
pear tree issues #870792
Asked May 30, 2024, 3:03 PM EDT
Lane County Oregon
Expert Response
1. What variety of pear is this and what is the rootstock?
2. Did you test the soil prior to planting? If yes, what were the results of the soil test?
3. How did you plant the tree and did you use the native soil or add any amendments?
4. How is the drainage in this area? Do you typically see standing water after a rain storm?
5. Do you see any symptoms on the trunk or branches?
6. When did the symptoms start and have they changed or spread on the leaf or to other leaves? Or did the symptoms appear suddenly and haven't progressed?
7. Is it possible to take a photo of the symptoms on the underside of the leaf?
If you could provide a little more information, I will take another look at the case.
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1. What variety of pear is this and what is the rootstock? Joeys red flesh on p. communis
2. Did you test the soil prior to planting? If yes, what were the results of the soil test? No I didnt test
3. How did you plant the tree and did you use the native soil or add any amendments? I had a friend here who had brought them to me from a class she took. We mixed native soil with some compost from lane forest prod and sprinkled something, mitochondrial mix?
4. How is the drainage in this area? Do you typically see standing water after a rain storm? No the drainage seems good. No standing water in the area
5. Do you see any symptoms on the trunk or branches? they seem ok
6. When did the symptoms start and have they changed or spread on the leaf or to other leaves? Or did the symptoms appear suddenly and haven't progressed? if it is progressing it is happening slowly. Not sure how quickly it came on. Hadnt really looked at the trees for awhile, maybe 2 weeks, and noticed it
7. Is it possible to take a photo of the symptoms on the underside of the leaf? attaching
Thanks
I think this is Fabraea leaf spot, but I can’t completely rule out Pacific coast pear rust. Fabraea leaf spot, a fungal disease, starts as reddish to purple pinpoint leaf spots that are 1-3 mm in diameter. The spots are found on the upper and lower leaf. The spots grow to 10 mm inch in diameter and develop a dark brown or black interior. Severely infected leaves become necrotic, turn yellow, and drop prematurely. To manage, rake up and dispose of fallen leaves in the fall to prevent overwintering of the fungus. Water at the base of the tree and avoid overhead sprinklers or irrigation that wets the leaves. There are some pesticides that can be sprayed, and any early season fungicides applied for scab will also be prevent Fabraea infection. Sprays should start in the early spring at green cluster if it is a rainy spring and the disease was prevalent last year; otherwise, wait until white bud, and apply at 10-day intervals for 3 weeks. Mancozeb is effective and one study showed that horticultural mineral oils are also effective. There have been reports of resistance buildup to fungicides, so if you use a fungicide, alternate sprays between mancozeb and horticultural oil to prevent resistance. The fungus overwinters on infected leaves and fruit, so removing all fruit and raking up and removing fallen leaves in the fall is one of the most effective measures. For more, refer to https://pnwhandbooks.org/plantdisease/host-disease/quince-cydonia-oblonga-leaf-spot
Pacific coast pear rust is also a fungal disease that affects pears in this area (as does trellis rust). You often see yellowish spots with pustules on the leaves and fruit. I do not see spores or fungal fruiting bodies in the pictures you sent, but they may not be visible in the photo. Rust fungi typically require different hosts to complete their life cycle, the primary host (e.g. your pear tree) that will display severe symptoms and a secondary host (e.g. an incense cedar tree that is nearby) which may only display minor symptoms. Management practices include collecting and discarding infected leaves and fruit, pruning out infected woody plant parts, and removing alternate hosts (which may not be practical if the cedar tree is in a neighbor’s yard). There are pesticides, but they are only registered for commercial use, so you would need to hire a licensed pesticide applicator. For sprays to be effective, they have to be applied when swollen, orange telia are present on the cedars (which is usually around bloom). For more on pacific coast rust, refer to https://pnwhandbooks.org/plantdisease/host-disease/pear-pyrus-spp-pacific-coast-pear-rust
and https://extension.oregonstate.edu/news/watch-out-rust-can-jump-incense-cedars-fruit-trees.
Look for changes in the spots. If they grow and turn blackish-brown in color, then Fabraea leaf spot. If they develop some bright orange pustules, then pacific coast pear rust.