wild pear leaf issue


I have a collected wild pear (from a field near Owen Sound) that will one day be a bonsai. For the past 3 years it has been growing well in the ground to fatten it up. A few days ago I noticed that a number of the leaves are browning in places. Could they be reacting to the sudden heatwave we’re in – no rain, intense heat and sun? I believe wild pears also suffer from rust but I don’t think it looks like rust. So my question is: Can leaves get scalded by the sun? As soon as I saw this I watered the tree well and the leaves perked up but the “burns” are still there. They only seem to be on the leaves that get the most direct sun. Just to be safe I built a little “shade screen” to sit above the tree and take the edge off the sun.
Love to know your thoughts and how I can treat it.
I’ve attached some photos.
Thanks. – A


Dear A —

Thank you for consulting Toronto Master Gardeners, and sending the very clear photo.  Making a bonsai is certainly an  ambitious project.

I think that your diagnosis and your treatment are both correct.  I looked at a lot of pictures of various kinds of rust and other diseases that pear trees might be subject to, and the pattern of infection does not really resemble any of them.  But pear trees are quite sensitive to heat and drought (more than apple trees) and Toronto is having a lot of both right now.  (You don’t say exactly where your tree is now, but if it came from Owen Sound to Toronto, it may notice the difference more.)  However, you should continue to observe the leaves closely to ensure that some other disease of pest doesn’t become more apparent.

The Ontario Ministry of Agriculture, Food and Rural Affairs has a detailed and useful web page which describes both the cause and the best response for leaf scorch in pear trees:


Another site you may find useful is:


So as this drought continues, keep that water coming, and best wishes.