While September and the fall may be around the corner, some Ontario residents have already noticed the leaves are changing colour. The red, yellow and orange burst of colour on deciduous trees like maple, oak and birch is usually the signal that fall is here and seeing it in August may seem a bit early for the leaves to start changing colour. It turns out, the wet weather is likely to blame.
“The trees that are changing colour early appear to be under stress,” University of Guelph Arboretum manager and certified arborist Alison Morrison said. “This year, heavy rains have been hard on urban trees with poor soil conditions and drainage. We seem to have heavy rain that moves quickly over the land and runs off without percolating through the soil to provide the tree with what it needs, or we have days of saturating rain that completely fills the soil and leaves the trees sitting in water.
” Neither condition is ideal, Morrison said. “Trees prefer a slow trickle that soaks in without oversaturating, leaving space for air and not drowning the very important soil fungi and bacteria that support a tree’s nutrient uptake.” Another issue adding to the stress on the trees this summer is the heat and humidity, which has created perfect conditions for fungal pathogens and some pests and diseases to breed in trees, Morrison said.
“Many species are suffering from various mildews, rusts, scales and wilts.” Healthy trees have robust immune systems that allow them to combat th.