pear trellis rust

(Question)

Hi,

I believe our ornamental pear trees have trellis rust. We have five in total. They are planted next to cedars not junipers. We do have junipers in the front of the house and are unsure if surrounding neighbours also have them. What can we do to remove the rust or prevent it from coming back next year? We just planted many of these items so they are fairly new to our property. I’ve attached a photo.
I look forward to hearing your advice. Thanks.

(Answer)

Sadly many ornamental pear trees will have this fungal disease. You are correct that it alternates between pear trees (summer host) and junipers (winter host). Although you don’t have any junipers in the immediate area, the spores of the fungus can travel up to 6 km on the wind. As you are no doubt living within 6 km of someone with a juniper, your pear tree will inevitably be infected every year with new spores. It can, in severe cases, completely defoliate a tree. This is obviously much more of an issue with pear fruit tree in Ontario, nevertheless, there is no fungicide registered in Ontario that can control this disease. Please read a previous post to our website for more information.