Are our oak trees doing harm to our raspberry, blueberry and blackberry patches?
Question:
We have so many oak trees on our property. Between the leaves and the excess acorns left over from winter, we have excess of everything in our gardens. The grass doesn’t seem to like them so I will try to rake them off but are they doing harm to our raspberry, blue berry and blackberry patches?
Answer:
Kate Garland, Horticultural Professional
Oaks are an incredible habitat tree, supporting over 200 species of caterpillars alone and one of the most beneficial trees for supporting biodiversity in our region. However, they can be messy and some of the chemicals they emit, such as tannins, can have a negative impact on the growth of neighboring plants. From what I can find in the research, there’s still more to be understood on the allelopathic impacts of oak on various species and I couldn’t pin down any reference that specifically mentioned brambles or blueberries. To be on the safe side, I would plant those crops as far away as possible from the oaks to not only minimize exposure to those tannins, but also reduce competition for light, water and nutrients. Oaks have a very dense and shallow root system that can serve as significant competition to neighboring plants. Cleaning up the debris will also reduce the allelopathic chemicals.