Fungus Among Us–Anthracnose

Anthracnose is a fungus that most associate primarily with our native dogwoods, cornus florida.   In fact, that’s what the above photo is of–anthracnose on my white native dogwood.  It doesn’t kill them–this tree has had anthracnose just about every year that I’ve lived here and I’ve been in this house 19 years now.  But it is disfiguring and it can weaken the tree and leave it susceptible to other problems that dogwoods are susceptible to like borers, so it’s not a good thing.

 A close up of this leaf shows how truly disfiguring the fungus can be. And because it overwinters not only in leaf litter but in small branches and shoots, it comes back year after year (as I’ve mentioned, this tree has had the fungus every year since I’ve lived in the house).

As this Fact Sheet from the University of California show, anthracnose is not just a disease of dogwoods, however.  It can affect many other hardwood trees and ornamentals as well as fruits and vegetables as well. They suggest that the fungus can be managed on a small scale (presumably with the veggies) with a fungicide but I wouldn’t want to eat vegetables treated with a fungicide so I just let my cucumbers die every year once they get that wilt spread by the cucumber beetle.    Some years I’ve planted late enough that I’ve missed the beetle–and the wilt–entirely.

The Fact Sheet from UC Davis has a list of resistant cultivars that can be planted in lieu of susceptible varieties of plants and I was pleased to see not just the Kousa dogwood, which doesn’t have a very high wildlife value but the Cornelian Cherry (cornus mas) a very early blooming type of dogwood with pretty yellow flowers and a smaller reddish fruit that has a much higher wildlife value than the kousa.

If you are searching for an alternative to our native dogwoods and don’t like the look of those ‘Rutgers cross’ trees, take a look at those.  You do have to like yellow flowers though.

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