Spruces and disease or mites?

Asked April 21, 2019, 11:30 PM EDT

Would like some help identifying what's attacking 2 Alberta spruces and 2 globe spruces in my front garden and what to do, if anything, to save them.

First, let me say that we did, at one time, have a Fat Albert blue spruce nearby these other spruces that was removed 2 years ago because it was slowly killed by what we were told was spider mites. From the bottom up. An arborist stopped by and diagnosed that along with something else (I can't recall) that was causing white looking sap to drip down the trunk. He also said the tree was stressed out because it was planted in a raised retaining wall bed. I mention this because I'm thinking those mites, having lost their food supply, have spread to the other spruces. They were all happy and healthy whilst the Fat Albert blue spruce was slowly dying.

The first picture shows the sunny side of one of the alberta spruces with the globe spruce in the lower left. There is a mirror image of this arrangement of spruces on the other side of our front window. The sunny side of the alberta looks all happy, but you can also see some die off beginning on the front of the globe spruce that JUST started to be noticeable this spring. The alberta spruce is approx. 15 years old. The globe spruce is even older, since it was here when we moved in...so it COULD be approx. 25 years old or more.

The second picture shows the shady side of the alberta spruce...practically bare ! Maybe the mites like shade? or could it be a disease that flourishes in the shade? the needles are just turning brown and falling off. I have looked closely but can't really see any critters, so I just don't know.

The third picture shows a close-up of the globe spruce's needles. And this is only happening on the sunny, front side of the shrub. All other sides look very happy and healthy.

I think it's safe to say that the alberta spruces are goners. I don't think they would ever develop new needles even IF we could kill what ever is killing them.

So here are my questions:

1. since the globes have just a smaller amount of damage, can they be saved? Yes they are old...so if their fate is the same as the Alberta's so be it. But it's worth a try. What is the treatment?

2. My bigger concern is how to manage and protect this entire bed. It goes from one end of the front of the house to the other. With azaleas between the alberta's and a dwarf Japanese maple at the other end. (It's hard to tell my story with only 3 pictures.) It seems to me as if those mites ….or disease.... is just spreading from one end to the other. I'm worried that if I replace these shrubs, they will suffer the same fate because of a mite population that is living.....in the mulch? in the soil? That will just spread. How can I ensure an adequate die off of whatever this is BEFORE I spend hard-earned capital on new shrubs? If I remove these dying shrubs, I worry the mites will just jump over to the azaleas or my Jap maple !! How can I prevent that?

3. Once all of this is resolved, can you suggest better choices of shrubs for my garden that might be more resistent? We have a horrific deer problem in our neighborhood so, something with needles would be best (cypress and arborvitae are out, they are deer winter salad). Even the azaleas are stripped of all foliage each winter (no more flowers, see 2nd picture to the right of the alberta, bare azalea), but that might be what's saving them because the deer may be eating any leaves that may have been infested with mites ! (strange luck)

Any guidance would really be appreciated.

thanks in advance

Jeanne Murphy

Howard County Maryland disease issues shrubs mites deer damage trees

3 Responses

We don't think that any disease or insects are necessarily "spreading" wildly through your beds. We think it is more of a function of the design of the garden, including the plants being used, and how they have been planted.
Healthy plants can often stave off insects and disease just like we can. But when stressed, they are more likely to suffer and succumb. Abiotic problems are environmental issues like poor placement, management or care that can stress plants and lead to problems.
For plants to establish well and be happy long term, they need to be well planted into a site that has their required culture.
For instance, azaleas do best in part shade, shallowly planted in an acidic soil. This area looks quite bright- (how much sun?) and many of the plants we can see are planted much too close to the wall of the house, where it is hotter with less air flow. This can lead to other problems like the spider mites on evergreens, and which will almost always be a problem with Alberta spruce. Mites however are rarely a problem for many other plants, so don't worry that they are taking over.
When planting, you always want to consider and plan for the mature size of the plant. If you don't have enough room there, it's time to consider smaller plants at maturity.
We would recommend removing the Alberta spruce.
Azaleas look very unhappy. You might want to move them (if there is much left after removing dead wood) to a cooler area with part shade, avoiding late afternoon sun. They do not get spider mites, but they can get lace bugs, nutritional problems (like too much calcium from the soil near foundations) and deer do love them.

The 'globes' look like they may recover.
Other issues to consider in general. How deep is the mulch cover? It should only be 3-4 inches and never lay against the trunks or stems of plants. If it is, pull it back.
As you do, watch for signs of gnawing damage from rodents on the lower trunk areas.



Christine



Thank you Christine,

Over the years, things have changed with our shade canopy on our street. Used to have very large oaks at the edge of our property that shaded the yard perfectly for the azaleas. Those 2 trees died and were cut down. Those poor azaleas are now not only struggling with afternoon sun, but the deer stripped them clean over the winter, which is why they look so sparse.

But I get that the Alberta's are almost dead and the azaleas need a better home. I may have to give them away in the fall, because no matter where I put them, the deer will only eat them again.

I do have 2 more questions please.

1. What should I do to help the globe spruces? What sprays? I plan to fertilize and prune, but fear that I'll only expose more "deadness". What actions should I take for them?

2. Can you suggest, or point me to a source, to help me find appropriate shrubs for this sunny area? Or maybe you know of a local nursery who can help me?


thanks!

Jeanne Murphy

1. Prune out the dead material. Water during drought.

2. Junipers love it hot and sunny and deer are not a problem. You could also try holly or possibly pyrecantha. You could try an ornamental grass. Switchgrass is native. Calamagrostis is attractive and not invasive. Consider native deciduous shrubs such as American beautyberry, fothergilla, or clethra.

We cannot recommend nurseries, per se. Look for ones with knowledgeable staff.

Ellen