I recently moved from Michigan zone 5 to Tennessee zone 7. I brought several plants with me as I couldn't leave them behind. Anyhow I had this problem in Michigan as well with my beautiful Spirea. It flowers just beautifully then after the flowers are done I run into problems with parts of it drying out, dying or whatever it is doing. Should I prune that branch or leave it? Hope I made some sense
It's one of three things, either Fire Blight, a fungal leaf spot or verticillium wilt. It's important to know which because the treatments for the first two are entirely different. Unfortunately there is no treatment for verticillium wilt. Do the dead leaves hang on the branch or do they drop right away when they die? If a fungal leaf spot the leaves drop quickly. There are various sprays for controlling fungal leaf spots. Leaves on a Fire Blight infected branch die and hang on. Fire Blight is pruned out to healthy wood being careful to disinfect the pruners between each cut. Fire Blight is a bacterial infection, hence treated with different sprays. Verticillium wilt is a soil born fungus that plugs the vascular parts of the branches and starves the leaves. It has no treatment. Sometimes the affected tree/shrub will compartmentalize the fungus and grow through it. Or it can slowly progress from year to year resulting in eventual plant death. The only hope there is to keep the shrub well fed, with adequate water. If you have verticillium wilt then all future plantings should be verticillium wilt resistant. Once you have it in the soil it's there for keeps.
The dead leaves hang on the branch. So I just prune them off? Thanks so much good advice
If it's fire blight you prune out the entire infected branch. If there are multiple branches disinfect the purners after each cut. Spray with the correct chemical. The link below is an example of what you need. You should be able to find this product or a similar one at any good garden center. If it's verticillium wilt prune out the dead, water as needed, fertilize next spring and hope. It may or may not outgrow the fungus. Remember to choose verticillum wilt resistant shrubs, trees and plants in the future.
http://www.planetnatural.com/site/fire-blight-spray.html
Thank you so much
