Landscape Contractor Perspectives
Extensive Deer Damage in rural and some urban areas. Picea glauca ‘Conica’ (Dwarf Alberta Spruce), Pinus strobus (White Pine), Chamaecyparis (Falsecypress) have windburn on both the south and west sides of the plants. Still a bit early to tell on other plant material, as the cold weather has slowed plants coming out of dormancy. I'm finding damaged tree limbs and some broken Taxus (Yews) and a few deciduous plants, due to the weight of snow, wind and storms. Mostly, I'm finding the perennials are coming up as usual.
In general more death, dieback and injury; lots of winter burn, especially on Taxus (Yew) and Buxus (Boxwood) and more salt injury on material near roads & walkways. Also seeing death of some plant material that would have been marginal in old zone 5...such as certain Cercis (Redbud) varieties and Cedrus atlantica (Atlas Cedar). There is much more dieback on Rosa (Rose) and Mahonia. On a positive note... we'll have more water and those plants that had prolonged snow cover fared better.
Grand Rapids Area
We are seeing more than usual amounts of snow mold on turf. Also crushed (bent and broken) limbs due to snow and ice falling off of roofs. Winter burn on Ilex crenata ‘Sky Pencil’ (Sky Pencil Holly)...not sure if it is due to the extended length of cold temperatures or if wind related, perhaps both.
Most significant in our area is broken or snapped branches from the weight of the snow. We are also seeing damage from rodents and small animals where they have chewed the bark off of the wood shrub material all the way around the stem. Frost was deep where there was minimal or no snowcover.
So far (still waiting for the plants to thaw) it appears that Forsythia blooms above the snow line may have been damaged, Cornus sanguinea 'Winter Flame' twigs are brown instead of yellow to red. We’re also seeing extensive rodent damage—any plant material above the snow level has extensive damage including Thuja (Arborvitae), Euonymus alatus (Burning bush), Ilex verticillata (Winter Holly), etc. May have lost a fair number of Euonymus alatus (Burning bush) due to rabbit girdling stems at ground level or branches that were exposed. The snow did provide a great cover for voles, letting them make tunnels to their favorite food source. I will be waiting to see what perennial crowns have been left that might be able to grow. By the looks of the tunnels and missing crowns, there is extensive damage. A fair number of Buxus (Boxwood) suffered winter burn above the snow line.
Michigan State University, Department of Horticulture
Broadleaved evergreens have been hit hard by the winter conditions. Damage includes foliage desiccation and death of terminal buds. The snow level indicates the line between healthy and damaged foliage. Please note, Even though the foliage is brown, it doesn’t mean that the stems are dead. To tell, scratch the stems with your thumbnail, light green is good, tan or brown is damaged. We have seen some flower bud damage on Cornus florida (Flowering Dogwood) and other flowering trees will also be affected. People can check flower buds on their ornamental trees by breaking off the bud; light green is good, tan or brown is damaged. Flowers buds may be killed, however, vegetative buds giving rise to new stems and leaves may be fine. Leaf and Stem buds can take a lot lower temperatures than flower buds.
Narrowleaved evergreen shrubs have also shown signs of winter damage. The most obvious is Taxus (Yews). Again even though the needles are brown, it does not mean that the stems are dead.
The best advice we can give is to wait until buds break later in the spring. Time will tell if flower and leaf/stem buds are dead. What appears dead could be fine.
The most obvious issue that is showing up so far is winter burn on Conifers.
We will also likely see dieback on some deciduous trees and shrubs, especially anything that might be considered marginally hardy. Liquidambar (Sweetgum), Cercis canadensis (Redbud), and Taxodium distichum (Baldcypress) are some examples of plants where we may experience some problems.
In most cases the best advice is 'wait and see'. Winter damage can often appear worse that it really is, especially for some of the winter-burned conifers. Buds may be completely unaffected even though the tree has extensive browning. For deciduous trees and shrubs the same advice applies; it's best to let things flush out and then determine what's alive or dead and what needs to be pruned out.