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Q: Deer have stripped the needles from two types of evergreens in our foundation plantings this winter, even though we had them covered with bird netting.

We watched the deer pull at the needles with their mouths, despite the netting, and when they pulled upward, they stripped the needles, which then fell to the ground. Is there any hope, or can you suggest other shrubs that would be more deer resistant? It鈥檚 been a yearly battle. 鈥� Linda B.

A: The shrub in the photo appears to be a Mugo pine, and by the looks of it, what didn鈥檛 get damaged by deer suffered some winter burn.

Will it recover? It鈥檚 usually best to delay action until after mid-May to see if any regrowth starts. There鈥檚 plenty of time to replace the shrub if there are no signs of recovery.

I believe in giving plants a chance, but I鈥檓 afraid I鈥檓 not optimistic about the Mugo pine鈥檚 recovery. When evergreens are severely damaged, the branches don鈥檛 have the ability to recover and generate healthy new growth the way leafy, deciduous shrubs do.

If this were a deciduous shrub that had been deer-damaged, it could be pruned back severely, and would bounce back better than ever. Evergreens don鈥檛 share that recovery potential.

What about deer-resistant shrubs? I always hesitate to pass along lists of plants that are reputed to be deer or rabbit-resistant, because I鈥檝e often encountered plants on the lists that were ruined in our own yard by these animals.

If deer are hungry, they鈥檒l consume shrubs on the resistant list. For example, your Mugo pine that the deer found so palatable is on the deer-resistant list of a reputable university.

Shrubs to try include dogwood, Meadowlark forsythia, lilac, juniper and viburnum. Mugo pine was on the list, but your deer apparently didn鈥檛 read the list.

Fencing works where practical. Because deer are herbivores, repellents made of animal byproducts are worth trying, such as Liquid Fence and Plantskydd.

Q: I can鈥檛 believe the level of winter burn I鈥檓 seeing this spring. The usual suspects were hit very hard, like yew and arborvitae, but I鈥檓 seeing significant burn on blue spruce and pine trees. 鈥� Matt E.

A: Thanks for your observations. I鈥檝e noticed the same thing as I drive around our communities, and I鈥檝e received many emails about winter-damaged evergreens.

Every so often, the region receives winter conditions that cause widespread burning on evergreens, resulting in brown needles. Luckily, many evergreens escape the burn, but every 10 years or so, we see higher incidents of winter damage.

What causes winter burn? University of Wisconsin sums it up well, indicating there are many factors that interplay, making it difficult to pinpoint one single cause.

Warm fall temperatures can cause evergreens to go into winter in a tender state, not having 鈥渉ardened off鈥� sufficiently.

Cold injury can occur in mid-winter when temperatures drop sharply at sunset after foliage has been warmed and thawed by bright winter sunshine, often intensified and reflected by snow.

On sunny winter days, needles can lose water, and the frozen roots can鈥檛 replenish it, causing desiccation. Winter winds cause water loss and dehydration.

Evergreens that go into winter in a well-hydrated state are less likely to suffer winter burn, although that doesn鈥檛 make them immune. Foliage under the snow line is often protected from winter burn, while needles exposed above the snow may be burned.

Winter burn tends to be worse during 鈥渙pen winters鈥� having little snowcover, cold temperatures and howling winds.
Will evergreens recover? The best advice is to wait and see what happens. If the evergreen will recover, new growth sprouts will be evident in May.

To check for life in branches, scratch the outer bark, looking for a fresh green layer, the cambium, under the outer bark. Dead branches will snap when bent.

If upper portions of evergreens have been killed, they don鈥檛 rejuvenate the way leafy, deciduous shrubs can. Removal and replacement might be the best option.

If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at donald.kinzler@ndsu.edu . Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.