Drought (?) strategy for young Nannyberries

Question: Hello, I have several Nannyberry viburnums which I planted as bare roots three years ago. In the past few weeks, the leaves on many have very gradually been turning a dull faded color, and eventually getting curled edges but not actually being “droopy” early on. One of my pics shows a bush among three other unaffected Nannies. I don’t see any obvious egg cases or suspicious insects. Watering does not seem to have an effect, and I can’t keep scrambling around with a water can. Would cutting them to the ground help the roots stay alive? I have all kinds of young native shrubs and trees, and the only other species I’ve noticed with this is a couple vigorous elderberries. Not all of the leaves are affected. They’re not droopy and have set berries just fine.

responder: Jane MacKnight  Replied August 04, 2024, 1:05 PM EDT
response: Sheri: I have to admit it's hard to diagnose from photos. As a native species, nannyberry viburnum ought to be tolerant of local soil, climate etc. How have the plants done in the past two years? Have you seen the leaf dieback before?  The photo of your twig looks like it could be viburnum leaf beetle (VLB) which can a problem for nannyberry viburnum plants.  Here's an article that provides lots of information including treatment options, Viburnum Leaf Beetle | Ohioline (osu.edu). The article includes photos of the beetle. Since you also write that the drying wilting leaves are also on some of nearby elderberry plants, maybe it's not VLB.  Crown borers are species of moths that chew bark but your photos don't show evidence but here's an article with some photos so you can check.  Viburnum Crown Borers (illinois.edu)  The brown curling leaf is not characteristic of VLB. Skeletonization of the leaf is typically seen with VLB. Have you seen this? Leaf curling can indicate a variety of issues, e.g. soil nutrient imbalance, over or underwatering as well as pest damage. Viburnums are susceptible to several fungi and fungi-like organisms, e.g. powdery mildew. What I can see of the leaves, they don't seem to have the characteristic whitish appearance on the leaves. Powdery mildew can be a problem when the plants are in shady areas. Are your plants in sun-partial shade? There are lots of fungi and organisms that act like fungi that could be non-specific to viburnum.  Not sure that I've been very helpful in coming up with a solution for you. You might check with a local nursery or take in a cutting from the plant.

responder: The Question Asker Replied August 07, 2024, 3:01 PM EDT
response: Hi Jane, thanks for your help! I think this is a conundrum I’ll just have to wait out.    This the first year any of the shrubs showed this problem. Most of these are partly shaded, but I also have one in full sun which is starting to show the same dulling of color and browning. One in worst shape is within a few feet of three others which are just fine! They all have the same amount of moisture and sun–   I'm familiar with the beetles/caterpillars and their damage—I drenched some mature Arrowwoods in March, and they’re beetle-free this season. Fingers crossed they won't be back again. None of the young bushes have been attacked yet.    One of the Nannyberries is in an out of the way spot, I think I'll cut it to the ground and see if it sprouts in the Spring. Maybe cutting it will help the roots survive, rather using all their energy trying to keep the leaves alive.....   Sheri      On Sun, Aug 4, 2024, at 1:05 PM, Ask Extension wrote:

responder: Jane MacKnight  Replied August 07, 2024, 3:09 PM EDT
response: Sheri: It is a conundrum. I've just lost a viburnum to heat and dryness -- we were gone for 2 weeks and it was too hot without enough water, but it was under stress already.  I would do the same thing --- cut back one of the plants. If the roots are healthy, it out to send up shoots in the spring. Thanks, Jane