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Dead Holly Limbs
There have been limbs dying on hollies locally for several years now. This damage is prevalent on ‘Nellie R Stevens’ Hollies. I see it in my daily driving all over the place over the last few years.
When we see this type of damage, single limbs dying randomly in a plant, we know that something is girdling the stems. Girdling means that something is killing the tissue in the stem. Then the rest of the limb dies.
Causes
Anything that cuts the water supply to a stem can causes the limb to die. It can be physical restriction such as an object wrapped around a stem. The problem can be chewing by animals. Other causes are insects or diseases.
I hypothesize that we are going to see latent storm damage in trees. Even if a tree did not topple, it likely had roots or limbs broken from the high winds. I suspect we will see similar damage in deciduous trees. Maybe it is showing up in the evergreens first?
Winter 2025 we are seeing holly limb death caused by sapsucker damage and hornet damage.
Squirrels – I have seen squirrels strip the bark off of hollies causing this kind of damage.
Squirrels sometimes strip bark off of limbs.
Woodpeckers – Sapsuckers peck concentric rings of holes in regular rows in the bark of hollies in the spring time. The holes are small and hyphen-like. The birds harvest sap from the holes. Wrapping trunks in burlap may protect trees. Often hornet damage and sapsucker damage appear side by side.
Fungal Infections – Fungal infections can enter a cracked stem and girdle the stem, killing it. Cracked stems can result from environmental extremes such as severe cold or high winds. The swollen cracked area on the stem that results from a fungal infection is called a ‘canker’. I suspect that in many cases the damage we are seeing is a stem girdling canker fungus. Inspect the dying limbs and see if the stem is swollen and cracked. If so, it is a canker and you should prune the limb all the way past the canker.
Bartlett Tree Experts in Brevard, NC was first to note that a “pink disease” (likely referring to Erythricium salmonicola) has been causing cankers in trees and shrubs in western NC. As with any disease it’s important to take action to prevent further spread by avoiding stem damage and by pruning out infected stems. Symptoms include stem and branch cankers, gum exudation, and swelling or sunken areas on the main stem and branches, as well as cracking or splitting bark and dieback.
A fungal canker on a cherry laurel branch.
Fungal canker on holly (possibly Pink Disease, a new pathogen).
This ‘Pink disease’ close up shows the pinkish webbing that forms on infected limbs. Image from Bartlett Tree Experts.
Cold damage – I chatted with a nursery grower recently and he believes a lot of the dead branches we are seeing in hollies are from cold damage. It was -10 degrees F here for two nights in a row in December. For sure, I have seen hundreds of plants damaged by the cold. Why would the cold damage just individual branches die on hollies while whole plants died in other species? That I cannot answer. But I have inspected some of these plants and there is no other sign of damage, insects or disease.
These potted hollies have dead branches that show no sign of disease, insects or other damage. I suspect cold damage is to blame.
Over-shearing – When you shear a plant you remove the newest leaves. In an evergreen plant, the new leaves are the most productive leaves photosynthetically. Photosynthesis produces the food for the plant’s growth. When you remove the new leaves and leave the old less productive leaves year after year, plants cannot produce enough food to thrive. This causes the plants to get weaker making them more susceptible to problems. Sheared plants are less healthy and shorter lived than naturally maintained plants.
Shearing also encourages dense leaf and branch production at the ends of branches. The dense branching and leaves shades the interior of the plants. The leaves inside of the plant are shed because of the lack of light inside the plant canopy. Over time sheared evergreen plants have a shell of leaves on the outside of the plants and no leaves on the inside. This shell of leaves can trap moisture inside the plant and lead for fungal infections.
Heavily sheared plants eventually start to decline in health. Limbs die and gaping holes are left in the hedge. Overtime the planting will simply fall apart.
Holly decline due to over-shearing year after year.
Solutions – In most of these cases, there is little you can do. Stopping a squirrel is impossible short of lethal control. Unless you can find the hornet nest you can’t stop them. The fungi are not curable. Really the only thing you can do is to avoid over-shearing and keep the plant healthy so that it resists damage and recovers quickly. Plant the right plant in the right place, plant it correctly and fertilize and water as needed. Finally, many times hollies have underlying problems that make them weak leading to disease susceptibility so look for signs of improper planting, wires or straps wrapped around the stem, etc. Often hollies are planted without removing the packaging material which can lead to plant health issues.
Nylon strap wrapped around trunk is left from planting.
