Wilting leaves on burning bush
I have an established burning bush where all the leaves in 2 days have become wilted. I not found insects, but treated it anyway with insecticidal soap as I am a bit desperate. My drip system waters every other day with 1 gal in three spots around the bush (all emitters are functional). It is about 5 feet away from another perfectly healthy burning bush. I am concerned about possibly verticillium wilt as I have no other explanation. I lost a Golden Smoke Tree 4 yrs ago to VW but it is about 100 ft away in the back of my lot. Why is my bush wilting? Thanks very much!
Larimer County Colorado
With the very hot weather, it could be due to drought. You didn't mention irrigation in your original submission...are these shrubs getting water? What direction do they face? With the rock mulch and if they are in a southern or western exposure, it could be drought stress. Is there fabric under the mulch? If so, it may be preventing water from reaching the shrub's roots.
While burning bush are very susceptible to verticillium wilt, that could only be diagnosed by a plant pathology lab.
In a perfect world, I would recommend that you remove ALL fabric and rock from under the shrubs and replace it with wood mulch. Though fabric does allow for water and oxygen infiltration, it will clog over time. Not knowing how long the rock/fabric have been in the landscape, some of the pores may clog and not allow for proper exchange. It could also be that the rock is simply too hot.
With verticillium we generally don't see an entire shrub collapse. So the fact the entire shrub is wilting, to me, leads me to more of a cultural problem. Only being moist 2" down may not be enough moisture for the roots as a whole, which will likely be 6-8" deep. Also keep in mind that some of these plants are grown from seed, so there will be some genetic variability--perhaps this is one that just wasn't as hardy or tough. I don't have a better explanation.
But again, if you wish to have it tested for verticillium, then you can contact the CSU Plant Diagnostic Lab and ask how to submit a sample: https://plantclinic.agsci.colostate.edu/
As for the Master Gardener program, I coordinate the local program. We have a statewide coordinator, Katie Dunker, who coordinates from a statewide level. Our county programs follow the guidance of state policies, but are able to make decisions based on local needs. We are fortunate in our program to have a very successful farmers' market in Old Town FC that helps support the program. Volunteers also have some programs, like Tree Team and presentations, that bring in funds to support the program. There is an annual state fee that all volunteers pay to support statewide support.
I cannot make this text black and non-underlined for some reason, but if you wish to continue the program conversation, feel free to email me: firstname.lastname@example.org
Again, since it's the entire shrub, I think verticillium is unlikely, but only you can make that decision whether or not to get it tested. If it helps with your peace of mind, then it might be worth the expense. You could always contact the lab to find out potential costs.
I also can't predict whether or not it will recover--if only I could! As the summer progresses, check for buds that will set for next year's growth. You'll start seeing them soon.
Also, the symptoms of over and underwatering are similar, so proceed with your watering with caution.
My position is a CSU-funded position, with support from Larimer County. You don't need to make a donation, but I appreciate the offer. It was Dr. Tony Koski who visited your yard last summer. I believe I was out of town, but he was available to do the visit. If you feel inclined, you could always send a quick note to the Larimer County Commissioners--they always like to hear their investments are worthwhile.