Anthracnose killing my lupin, Verticillium Wilt killing my penstemon
I read that I have to dig up and destroy all affected plants. But that the fungus lives in the soil for a long time afterward. I read that I can use solarization on the affected soil, but can I just apply fungicide to the soil right away and then replant???
Grand County Colorado
Anthracnose is not a soilborne fungus. There are foliar fungicides on the market that can treat for this problem. The issue is whether lupine or other ornamental perennials are listed on the label and timing of the application. Also, good garden cleanup at the end of the season can reduce anthracnose as the spores of the fungus can overwinter on the plant material left in the garden.
There are no fungicide drenches available for Verticillium. This pathogen is soilborne and soil solarization is probably the best way to reduce populations of the pathogen. However, verticillium is endemic in our soils so even with solarization it is best to plant verticillium resistant plants in that area even after solarization.
I hope this helps answer your questions.