I’m a new pear grower in southern California. I received these two 4 ft bare root trees from raintree in January and planted them in the ground after soaking the roots in water. One is harrow delight and the other is Korean giant. They had no branches and no leaves when I received them. The new leaves emerged about a month ago and looked great. At some point these black edges started to appear on many of the leaves, more so on the harrow delight. They do not look like fire blight (I only know what fire blight looks like on apples). It’s been raining a lot in southern California this past week, but I am unsure of the timing of the black edges in relation to the rainy weather. I dormant spayed both trees with copper before any leaves or buds emerged.
The first two photos are from the harrow delight. The last photo is the Korean giant. I’ve looked carefully for pests but noted none except for minimal aphids that were easily fixed with some soap and water spray. Could this be due to soap?? I use very mild/ diluted dish soap on everything for aphids and never had a problem.
I’m having the same issue with my trees. Put them in 18 months ago. Had the black leaves issue last year, looks like it’s back. What could this be? I have Copper (weak, the Bonide stuff), and Chlorothalonil. I could also bite the bullet and but Kocide 3000 if need be.
I never figured out the cause. If you Google “black edges on pear leaves”, everything under the sun was diagnosed. Here are some that I can remember being diagnosed, even though they all look identical in pictures:
A variety of blights
I decided to go DEFCON 1 with everything I got, including copper, streptomycin, tebuconazole, chlorothalonil, dormant oil, neem oil, and spinosad during last year’s growing season and this past dormant season. They didn’t get any worse and some of the leaves that grew afterward were spared. Unsure if what I did made any difference. My pears are still dormant and growing very slowly so I can’t tell you if the problem returned.
I think that the photos that both of you shared are ‘leafspot disease’, they start out as black spots on the leaves and the entire leaves turn black, I had it last year and it seems like insects spread it to the leaves when they chew on the leaves, in our case insects spreading it from Bradford pear trees, there are plenty of them in our area. I pulled the blackening leaves off as I has seen them, and the trees were fine. I have no idea if your trees are as resistant to it as mine are.
When new growth dries up and dies and then stops the issue is often pear psyla, the most common debilitating pear pest in the northeast. They are quite small aphid-like insects that require magnification to see clearly, at least for my eyes.
This article covers the issue and shows that psyla are also a problem in the west. Surround seems to be quite effective as a suppressant although the article doesn’t mention it. Even conventional commercial growers will sometimes use Surround for psyla control- it is a huge problem once it arrives in orchards. I grew pears in my orchard for several years before observing them.
Focus on the growing shoots- that is where the psyla go because there is more protein there. Do a dormant oil spray at 2%-3% just when pears say they are about to grow or at first sign of any green, then another hort-oil spray at tight cluster (green flower buds) but not more than 2%. then if you do about 3 Surround sprays starting at pedal fall and 10-14 days apart and I think trees will be adequately protected, but you can hit them with oil and Surround if you start to see too much damage in summer. At summer base it on what you see. If you want to protect pears from other spring insect pests you should tighten up the Surround apps a bit. I’ve always done 4 a week apart but one year the person I had doing the Surround apps did it every 2 weeks into summer and the fruit was fine. Maybe just luck, but I’m not an expert on least sprays with Surround.