For years the trees, shrubs and other plants in my forest garden have been incredibly healthy with no sign of disease on them. However this year pear rust (gymnosporangium sabinae) arrived and I only really became aware of it as a problem today when I noticed ugly galls protruding from the lower surfaces of certain leaves. These leaves have had bright orange spots for several weeks and had I been aware of the disease this would have been a warning sign. Pear rust is unusual in that it needs both pear trees and juniper bushes to complete its life cycle. This article has more details.
Before looking this up I had been round the garden and collected a small bag of all the affected leaves I could find. Fortunately the trees are all small and easy to reach! If I see the tell tale orange patches in future years I will take the affected leaves off immediately to save the trees the stress of playing host to this fungus.
Over recent years it has become my habit to reference the most relevant forest gardening principle(s) at the end of each blog post. And this principle highlights just how being a forest gardener is a never ending journey of ever increasing learning and deepening understanding of what is unfolding before us.
Forest garden principle: Polyculture learning is slow learning.