Blight / spore fungi??

Asked July 10, 2020, 8:20 AM EDT

Hello I have a hedge row along my driveway and some adjacent Russian Sage. One Sage is directly adjacent to the shrubs and two others a good twenty feet away near the front of our house. The hedges (not sure if it’s a boxwood - has small flowering bodies in the spring) has a leaf issue and I’m wondering if you can identify it from the following images. The leaves appear to eventually die and the litter below the shrub collects. The Russian Sage is splitting on many branches, also seen in photos, and branches appear to be wilting one by one. Important things to note are about two weeks of elevated temps near 90 and very night humidity here in St. Joseph, MN. Also, there is a downspout that empties onto the adjacent sidewalk and travels along the driveway edge / hedge row. I’m wondering if there is long term concern for these plants and I’ve read a lot about blight / fungi that can remain in the soil. Thanks so so much in advance! Dan

Stearns County Minnesota

1 Response

Your hedge is a hedge cotoneaster https://www.mortonarb.org/trees-plants/tree-plant-descriptions/hedge-cotoneaster There may be some other fungi going on with the leaves, such as quince rust, but the majority of the leaves seem to be suffering from powdery mildew: https://extension.umn.edu/plant-diseases/powdery-mildew-trees-and-shrubs I haven't been able to find any pests affecting your Russian Sage but it does look like a borer of some sort has invaded the stem. Or a caterpillar or slug has chewing a portion of the stem off. IF that photo is of the main stem, you probably don't want to cut it off. If it is a side stem, then I would cut it off and slit it to see if there is a borer inside If the drainage from the downspout disappears into the soil, there should be no problem. Watch for erosion.