In Ben Nobleman Park in Toronto, Ontario, where I planted a community orchard in 2009, I learned my lesson about disease on leaves early. In the first year, I saw a few orange spots on the leaves of one of our young pear trees. I ignored them.
The next year there were more spots and this time, they were on all three trees. By the end of that summer, the trees were covered with orange spots and looked like three miserable kids covered with chicken pox. Only then did I do my research and discover that our pear trees were infected with a fungal disease called pear trellis rust.
But that’s just one spotty disease that trees can experience. Over the years, I’ve seen all sorts of trees with spotted leaves. They may be big or small, brown, green or red, but they are never a good sign. Often they are signs of fungal diseases.
The important thing is to research the problem early. Some fungal diseases can be nipped in the bud with applications of an organic fungicide such as garden sulphur.
By the time we acted, it was too late. Our young pear trees were too weak and stressed and would never fully recover. We had to dig them out and plant apple trees instead.
Signs of pear trellis rust, a fungal disease.