A local arborist brought this in over the weekend -its Entomosporium leaf spot on an ornamental pear (probably a Bradford pear). It will not kill the tree but if you don't attempt to control it the tree may become weakened from defoliation. The treatment likes in changing the cultural conditions so that the inevitable coating of fine mist that is deposited when our 'June Gloom' overcast layer is really deep and gloomy dries out as quickly as possible, giving the fungi's spores less of a chance to germinate. Besides removing all the infected leaves and disposing of them in the trash (composting them could recycle the spores) this can be achieved by opening up the tree near the base using selective pruning, removing organic mulches under the canopy of the tree (they keep the moisture levels up too high) and making sure irrigation water isn't hitting the leaves or trunk of the tree. If infestations of Entomosporium are high it's not a bad idea to apply a copper fungicide until the weather gets drier.
|Entomosporium leaf spot on ornamental pear.|