Pear Leaves With Black Spots/Areas

Asked August 29, 2019, 7:01 PM EDT

We have two pear trees that were planted February 2018. One is a 20th Century Asian Pear and the other is a Ubileen. The Ubileen tree has no visible issues of any kind. Also, it has no fruit. The 20th Century Asian Pear has large ugly dark marks that occur in different locations on only some of the leaves. Some spots are at the base of the leaf, some are in the center, and some are on the tip. While a majority of the tree has healthy leaves, the number of discolored ones is growing. Most are on the lower parts of the tree. It also has fruit that is almost ready for picking. Some fruit has light scarring, but no visible sites of pest entries. I am including a collage that shows three leaves, front and back, with the spots. There are also a very few that look a bit different, more like something stripped the upper layer of the leaf off. I am including a photo of that as well, in case they are related. While they look totally different on the top, they look the same on the back. The trees are fifteen feet apart in Sweet Home, in the Cascade foothills and they have very good drainage. Possibly too good, as the well doesn't fill, so it has had deep watering twice the last month. I used fertilizer spikes as per the package instructions this spring. I did not do a copper/oil spray this winter (but I sure will this winter!). I did see a few leaves last week that looked like there was miniscule insect poops on a few leaves, but I saw no insects. I saw no poops today, but we had strong showers this morning. I have macro shots available of the area that looks like the top layer of the leaves were stripped off if needed.

Linn County Oregon

4 Responses

Hi and thank you for contacting Ask an Expert.
You have two problems with the leaves/pear trees. The first set of leaves with the black spots is most probably botrytis which is a fungal disease. The brown spots on the second picture looks like damage from sawflies (slugs) or pear psylla (black slugs). these slugs give off a honeydew type syrup which scars the fruit. Both will do great damage to your tree and your fruit.

Here is a link to learn more about this pest. The other sawflies eat roses and other plant leaves.

Botrytis can be somewhat contained by cleaning up and pruning all disease limbs (look for dark spots on the limbs). Clean all fruit and leaves around the tree and then add compost to the area for winter protection leaving the compost about 6 inches away from the trunk. Sprays for botrytis are numerous and some are toxic. For fungal disease in my orchard I use Rex lime sulfur, Neem oil and dormant oils. These three sprays have helped contain most fungal diseases and will also help with overwintering pests. All three will kill or smother pests and eggs. Rex lime sulfur can be found in farm stores like Coastal and Wilco. A number of organic sprays like Seranade (a bacterial spray that eats fungus), Insecticidal soaps and mineral oils are available in most stores carrying nursery products. If you buy Neem oil buy only 100% pure Neem (found on the Internet). Other Neem products are often mixed with highly toxic chemicals you would not want on your fruit. This may be a long process. After you have pruned the diseased limbs and leaves and bagged and thrown them away, spray the lime/sulfur, wait 10 days (per instructions on the container), then spray the Neem oil. epeat this spray cycle monthly on dry days with at least 8 hours of no rain. The weather sometimes doesn't help you out. Always read the and follow the instructions on the containers. Dormant oil can be sprayed later in the year. Fungal diseases are notorious for coming back again and again. Here is a link on organic sprays for pests. Do not spray any of these during blossom time, they will kill your pollinators.

There is a lot of information about this fungus and the pests. If you have any further questions, please re-contact us.

Thank you, Sheryl. We are headed to Wilco this morning.

I just went out to check and see no black spots on limbs, so I will pick off all affected leaves and start treating today. Should I pick off all fruit or is the Rex lime sulfur safe with washing the fruit before eating?

In case I do see stem spots while picking leaves, would you leave any stem cuts raw, or seal them, if done this time of year.

Again, thank you. I appreciate the time (and knowledge!) you shared.

Hi Leia,
As to the fruit, is it about ready to be harvested? Gently rock one of the Asian pears back and forth and if the stem comes loose from the limb it is usually ripe. Most pears will ripen off the tree but they need to stay on until almost ripe. How do you determine that, experience. I take my red Bartlett pears off when they are really red but still hard. They don't last long and if I leave them on the tree, they are too soft and going bad by the time I do get to them.
Asian pears bruise easily so handle with care like eggs and store in the fridge, they go bad fast too. If you have too many, drying them is a great way to preserve them. Store in the freezer afterwards for a few days to kill anything left after the drying.
I am advising you read the instructions on the lime/sulfur container as to how soon you can pick your fruit after harvesting. If your Asian pears are rock hard and won't come off the tree, I would not pick them now. Follow the directions and pick when ripe.
This time of year with the hot, dry weather, you can cut and leave the limbs to dry. Have fun with your new trees. Sometimes it takes a couple of years for fruit trees to even blossom, don't worry once they start, they usually don't stop. Have fun with your newly planted orchard.

So sorry, the sentence on spray and eating should read . . . can pick your fruite after spraying - not harvesting.