For people living in cold climates, a sunny, warm day that interrupts an otherwise gloomy winter is something to look forward to.
For evergreens in cold climates? Well...sunny winter days aren’t so sweet. Harsh sun actually works against evergreens in winter. Come springtime, these endlessly green plants might turn brown from the damage.
Below, find out why your evergreen shrubs may not have gotten off to a good start in spring.
MY EVERGREEN SHRUBS (BOXWOOD, DWARF ALBERTA SPRUCE) HAVE WINTER BURN. WHAT NOW?
Winter burn sounds pretty straightforward, but what exactly does it mean?
Here’s the gist—evergreen shrubs, unlike other plants, hold on to their foliage in winter, and it takes tons of moisture to keep their needles green throughout the season. Anytime bright sun or harsh wind is in the forecast, the needles lose moisture, and since the ground is frozen, plant roots just can’t take up enough water from the soil to replace that lost moisture. Eventually, the needles get way too dry, causing winter burn.
HOW DO I KNOW IF MY SHRUBS ARE AFFECTED?
Winter burn starts with the tips of shrub needles turning brown, and then eventually full needles on a whole section of the tree are brown and dry.
Not surprisingly, the discolored section appears on the side of the plant that gets the most sun or wind throughout winter. But that doesn’t mean winter burn is immediately obvious. Evergreen shrubs might look green and healthy leading up to spring, and then start to turn brown just as the growing season arrives.
WHAT ARE SOME TIPS FOR WINTER BURN TREATMENT? WILL MY SHRUBS RECOVER?
Odds are, an evergreen shrub that has winter burn will bounce back. Even though brown chunks might make the plant look dead, your shrub will more than likely sprout new needles.
To be sure, prick a small area of an affected branch with your fingernail or a pocket knife. It should be green and moist underneath. Any branches that are still green under the bark are alive and can grow new needles. If any branches are brown and dry underneath, you should prune those out.
Lastly, make sure your shrubs get lots of water throughout spring. They’ll thank you with a flush of new green needles!
CAN I PREVENT WINTER BURN BEFORE NEXT YEAR?
Kudos to you for thinking ahead! Yes, there are steps you can take to protect your shrubs.
Here are four things you should do to prevent evergreen winter burn:
Thoroughly water your shrubs in fall all the way up until the ground freezes. Hydrated plants have a much better chance at dodging winter burn.
Apply 3-4 inches of mulch to the ground beneath your shrubs and trees. That’ll seal in the moisture you’re giving them when you water.
Try an anti-desiccant spray. It’s a wax-like coating that helps evergreens avoid moisture loss in winter. Read more about anti-desiccant sprays in this blog post.
If your shrubs are directly exposed to harsh sun or wind in winter, wrap them for protection. Here’s how to wrap an evergreen shrub with burlap.
NOT SURE IF WINTER BURN IS THE PROBLEM? HERE ARE MORE REASONS EVERGREENS TURN BROWN.
A beautiful maple, resoundingly/photogenically magnificent in shades of orange and red in autumn. Colors long persistent, from initiation to the crescendo, easily 3 to 4 weeks. Although Acer griseum receives the majority of garden accolades, this is the most adaptable, cold hardy, heat tolerant and reliable. In truth I love both, also certainly Acer maximowiczianum and Acer mandshuricum, all affectionally documented as the tri-foliate maples.
The Dirr garden houses two pretty Acer triflorum specimens, one now three-trunked, due to me dropping a water oak, Quercus nigra, dead center. But it regrew and self-morphed into a pretty multiple-stemmed tree. Most trees in cultivation are single-stemmed with an oval to rounded crown. I believe the multiple-stemmed version is better purposed to display the exfoliating ash-brown, tan to orange-brown bark, much in the same fashion as river birch.
The species ranges from 20 to 30’ high and as wide under cultivation. Largest trees I know are positioned by the visitor center at the Arnold Arboretum. There is a 30’ plus tree on the Maine campus, Orono which has consistent beautiful orange-red fall color (see photo). Even young trees are quite full and uniformly branched. Certainly, beautiful as a specimen but in groupings of three to five, the effect is powerful, especially against evergreen backgrounds provided by pines, spruces and firs.
The leaves emerge caramel-colored with hints of red, maturing mid-green, developing the long persistent fall colors from mid-November to mid-December in Athens, GA. Called three-flower maple because the yellow-green flowers occur in 3-flowered cymes with the emerging spring foliage. Fruits are samaras with hard, bony nutlets and the attendant flattened, prominently veined, curved wing. Unfortunately, fruits are often void (without viable seed). Seed dormancy is complex and it takes two or more years of warm: cold cycles to facilitate germination. This is the reason the species is scarce in everyday nursery production.
Native to China (also Korea and Manchuria), described as reaching over 80’ (Flora of China), where it occurs in mixed forests at elevations of 1300 to 5600’. In the United States, I noted thriving trees from Minnesota and Maine to the Atlanta area. Under cultivation, any well-drained soil, preferably acid, full sun to partial shade, prove hospitable. Easy to transplant from a container but a 21/2” diameter tree in the Dirr garden took several years before actively growing. A meaningful observation relates to Cornus florida ‘Appalachian Joy’ located next to A. triflorum. The foliage of the dogwood flagged in severe drought; the maple unaffected.
Since all (most) A. triflorum are seed-grown, variation in fall color is to be expected. However, I have never experienced a dud. In 2017, I purchased an own-root selection, Artist Etching ™, with prominent exfoliating bark, from Song Sparrow Nursery. Added to the garden this year, it is fast growing and showing prominent exfoliation as a young pup. Cold, heat, wet, dry, acid, alkaline, like the postal service, the species delivers the fall color. To my knowledge, there are no serious insects or diseases. The nine-year old trees in our garden have never had as much as an aphid.
Ah, the iconic maple leaf! It’s one of the most recognizable tree leaves out there, and it usually looks fresh! The leaves shimmer green in spring before putting on a show and turning yellow, orange, and red in fall.
But what if your maple leaves develop unsightly brown or black spots in summer? Is your tree in trouble–or even a goner?
Take a deep breath! While those spots look worrisome, it’s just tar spot–a fungal disease that isn’t a big issue to your tree’s health. Learn more about maple tar spot and how to help your tree rebound below.
There are a couple types of fungi that cause those big brown or black spots on maple trees. They’re all called tar spot, and they most often affect:
As with most tree fungi, maple tar is more likely to happen if your area has been getting lots of rain!
The spots usually start developing in early-to-mid-June. Then, the dots are tiny and light green. So, you probably didn’t notice them.
Around August, those tiny spots become significantly wider and thicker. It will literally look like clumps of tar are stuck to the leaves. You may even see spots on the maple seeds – unless you were smart enough to plant a seedless maple without helicopter seeds.
Maple tar spot is mostly a cosmetic issue. The dots bring down the look of your tree – and can even cause early leaf drop.
But that’s about the extent of the issue. Maple tar spot rarely does any damage to the tree’s health.
If you’re really fed up with the maple tar spot, you can have a certified arborist and pesticide applicator apply a fungicide next spring. This is typically only recommended if your tree continually gets maple tar or it’s a prevalent issue in your area. Most tar spot is considered aesthetic and this method usually isn’t necessary.
Furthermore, to be effective, the fungicide must cover every single leaf, which can be quite the feat on mature maples. That’s why it’s generally best to treat and apply a maple tar fungicide on smaller trees.
The best way to treat and prevent maple tar involves a little elbow grease! As the leaves fall, rake and destroy all leaves. Do your best to get every single leaf out of the area, which in turn will remove most of the tar spot fungal spores.
Bagworms are back! by Chuck Royer
These invasive insects look like cone-shaped sacs that can sometimes be mistaken for pine cones. The sacs look like cocoons that hang from the tree branches. These cocoons or sacs contain bagworm eggs and once they hatch, they will begin to dine on the leaves and needles of your trees and shrubs. A heavy infestation on evergreens can cause extensive die-back and even death to the plant. Bagworms are fond of a variety of trees such as blue spruce, cedars, white pines and junipers. On deciduous trees, bagworms will strip the leaves, leaving only bare branches.
Left untreated, bagworms can defoliate branches, causing branch die-back and eventually kill the shrub or tree. The best defense against bagworms is an insecticide spray application. If the outbreak is severe, a second application may be required.