boxwood and pachysandra blight
We have various Hollis and Junipers in our driveway island--Star Junipers (pic1) Helleri Holly (Pic2) and Junipers (Pic 3) that were planted about 25 years ago that have all been dying back very slowly even though they have been fertilized with Holly Tone on a regular basis. (The only thing that does not seem to be affected in the island is the Cut Leaf Maple.) We wrote this off to old age, and were planning to rip everything out except the cut leaf maple and plant Boxwoods, until I started reading about Boxwood blight, which apparently can spread from infected soil and pachysandra blight (I know for a fact that our pachysandras in the next bed are badly infected by a blight which won't go away, even though I have been spraying them repeatedly with Daconil fungicide --see Pic4). My questions: 1. Is the browning of the plants in the island likely due to old age or a blight? 2. If a blight, what if anything can I plant in the circle that will NOT get infected by this type of blight that is deer resistant (we have lots), and relatively slow growing (<2 ft high hedge), attractive and evergreen? 3. What if anything can I do with my blight infected pachysandras? Should I keep spraying them or rip them all out too? What can I replant in that space which is for the most part very shade? Thanks in advance for your learned advice.
Howard County Maryland
We only received one photo of the juniper. You can send more photos.
There could be several reasons for browning. Junipers usually look good once planted and after a while decline due to lack of sunlight, winter injury, vole damage http://extension.umd.edu/hgic/voles-groundcovers, possible diseases, poor drainage, etc. Junipers grow best in full sunlight and a well drained soil. They will thin out and brown due to lack of sunlight. All you can do is prune dead wood.
Helleri hollies grow best in full sun to shade in a well drained soil.. If drainage patterns have changed it is possible you may be dealing with a rot root. Japanese hollies can be susceptible to black root rot Thielaviopsis. Do not replant Japanese hollies in this area.
We do not recommend planting boxwoods due to boxwood blight. http://extension.umd.edu/hgic/topics/boxwood-blight
There is a fungal disease called volutella that infects pachysandra. Volutella is not uncommon on old, unmanaged pachysandra beds.
Here is our page about it: http://www.extension.umd.edu/hgic/volutella-dieback-pachysandra-groundcover
As with any foliar plant disease, management goes far to promote better growth and less chance of a recurrence. This includes removal of diseased leaves, thinning of the bed by mowing or removing some of the plants so that there is better air circulation, and raking of debris from the bed when needed. Generally, anything that keeps the leaves more dry than wet is what you are after. The longer leaves stay wet, the more likely that diseases can get out of hand. Sprays are ineffective.
It will be difficult to find evergreen shrubs that grow in the shade and deer resistant. Most evergreen shrubs require some sun. You may have to consider a mix of different grundcovers and/or shade perennials. Consider hayscented ferns, Christmas fern (evergreen), Pa sedge, dwarf forms of American holly, dwarf Itea,
helleborus, Green & Gold, etc. Here is our deer resistant list http://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/non_HGIC_F...
I asked two questions at once which led to confusion. So let me simplify. We need to redo our island because the hollies and junipers are very sick or maybe too old (25+ years) See above pic and the ones attached below. (They may have gotten infected from infected pachysandra bed (see last pic below) which is adjacent but NOT connected. Can that be?) My first question: What can we plant in the island, that is in full sun, is deer resistant (we have many), blight resistant, evergreen, attractive, relatively slow growing and can be shaped? (we were going to plant boxwood but you recommended against it.)
My second question: Should I mow down the infected pachysandras, which appear to be infected with volutella (see the last pic below) so they do not infect the new plants which will be planted in the adjacent bed on the other side of the driveway? Will that kill the pachys or will they regenerate, and no longer be sick? Or does the blight remain in the soil and transfer to other plants anyway?
Thanks for your help.
Boxwoods and Pachysandra both get Volutella blight. Junipers are not well adapted to our climate. They will do well for a period of time, but they do get fungal diseases, mites, needle cast, root root, and/or winter damage and tend to decline over time.
There are not many options for deer-resistant, disease-resistant, slow-growing evergreens. Hollies and Chamaecyparis are two possible options and there are some low-growing cultivars of each. Rutgers University has a good resource for checking the "deer resistance" rating of plants (but there is no guarantee they won't browse). https://njaes.rutgers.edu/deer-resistant-plants/
You might consider some non-evergreen choices that are deer-resistant: ornamental switchgrass, deutzia, pyracantha, forsythia, bluemist shrub, yucca, and catmint are some choices that would do well in full sun.
Yes, you can mow and rake out the diseased foliage from the Pachysandra bed. Volutella blight is not known to be a problem that would spread to the other plants I listed above. Generally, anything that keeps the leaves more dry than wet is what you are after. The longer the leaves stay wet, the more likely that diseases can get out of hand. Fungicide sprays are ineffective; they suppress the disease but will not cure it. Any fungal spores remaining in symptomatic foliage can serve as inoculum to start a new outbreak if environmental conditions are suitable. https://extension.umd.edu/hgic/topics/volutella-dieback-pachysandra-groundcover