how to treat Black Root Rot in Japanese Hollies ?

Asked May 1, 2018, 6:28 PM EDT

I had 9 beautiful Japanese Hollies planted in May of last year. The shrubs dropped some leaves after planting and small clusters of top branches died after planting leaving small holes in the compact shrub, so I took sample to Valley View in Sept and they looked under microscope and found spider mites I had sprayed for mites by Scientific Plant Service and they were scheduled to spray again in May. Last month I noticed 1 plant dropped many leaves and another dropped almost all leaves - Scientific suggested I have Bartlett Tree/Plant Experts look at them and was told I now have Black Root Rot and some scale. They recommend 4 treatments May/June/Aug/Sept @$245 each (fertilizer, granulated sulphur and fungicide) but very difficult to 'fix' and may not 'fix'. the problem of black root rot. Would love to hear your feedback.

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5 Responses

The treatments for black root rot are preventative--not curative. They will not cure the current problem, just prevent more damage.

The fact that these newly planted shrubs are having all these problems suggests they are not suitable for the site where they were planted or are being stressed in some way. They are very sensitive to overly wet sites. Once they are stressed, they become susceptible to diseases and attract pest insects.
We hope the plants were covered by a guarantee and since it has been less than a year since they were planted, that you can replace them with a more appropriate species.

ECN

Thank you very much for your response. COULD THE TREATMENT PLAN SLOW DOWN the black root rot, mites and scale? I realize this is a broad question, but have to ask.
I'm not confident the "landscaper" will stand by his guarantee unfortunately!

Spider mites are generally not a problem on hollies.
Scale - depends upon the type of scale and life cycle. Send photos of the insects and damage that you are noticing.
Root rot - the fungicide for the root rot can slow down the problem but will not cure it.
If you decide to replace the plants, select another species of plant.

mh

Thank you so much for your valuable help!
You mention Hollies as not as susceptible to mites - however I have a serious deer problem - and they don't seem to mind eating prickly holly so choose the Japanese Hollies which they do no like. I know they don't like boxwood, so maybe I'll try boxwood although I know they can get a boxwood blight. Are they susceptible to mites, scale or black root disease?
How do I go about sending pictures? I live close to Shawn Road Extension facility.

You can take digital photos and attach them right to this reply by using the "Choose File" under "Images" below. You can attach three at a time.
For what it's worth, broadleaved evergreens in general look pretty rough this time of year after hard winters. If alive, shrubs will soon push out new growth and look a whole lot better. Don't be in a hurry to do anything until you see what may come.

As far as boxwood, they have many disease and insect problems.
We don't know your site conditions- sun-soil-water, space for mature size etc., but here is a our page on deer damage, and you will see a link to publications listing plants that tend to be deer resistant. Match those with your site conditions:
http://extension.umd.edu/hgic/deer

Also, just fyi, you will see on the list several hollies that are deer resistant.

cm