Winter Injury

Plant Material Maintenance

Temperature Fluctuation

Damage can occur from:Rapid/extreme fluctuations in tempExtended mild weather can de-acclimate

plants, leaving them vulnerable to rapid temp drops

Low Temperatures

Use USDA Hardiness Zone RatingSeveral mild winters can lull people to believe

plant will be hardy. (Cutleaf Japanese Maple) Plant marginally hardy plants in protected

sites. East side of buildingcourtyards

Frost Cracks

Long cracks on the south-southwest side of thin barked treesDue to temp fluctuations between day and

night; uneven contraction of the woodEx European Linden, Red Maple, Norway

Maple

Frost Cracks on Green Ash

Sunscald Injury Very similar to frost cracks; damage is an

elongated cankerWinter sun is lower in the southern skyThe lower angle of the sun can directly heat

the south and southwest side of a tree trunk during a sunny winter day

Subsequent freezing, night-time temperatures damage cells

Thin barked trees w/ smooth, dark bark are particularly susceptible

Sunscald on the SW side of a Chokecherry tree

More Sunscald Injury

Winterburn on Evergreens

Browning or scorched needles Due to desiccation

Winter sun & wind dries leavesTranspirational water lossReplacement water unavailable (frozen)

Can apply an anti-desiccant to prevent injuryReapply throughout winter

Snow & Ice Breakage

Heavy snow and snow piled on plants from driveways and walks

Multi-stemmed evergreens most prone to damage

Gently remove heavy snow from branches Do not remove ice from ice-encased

branches

Help Me!

Salt Damage

Damage appears in spring and early summer Scorching of leaves

Avoid heavy salt usage near plants Use salt tolerant plants near walks and drives if

salt needed. Most salt damage occurs from late winter

applications of salt. Avoid if possible. Use calcium chloride, or other safe de-icer,

instead of rock salt

Girdling by animals

Mice/rabbits/voles feed on bark and girdle branches. Growth beyond girdling dies in spring

Wrap trunks with screen wire or hardware cloth

Minimizing Winter Injury

Select hardy plants Avoid late summer pruning and fertilizing Water plants during dry periods until ground freezes Use mulch to conserve moisture and insulate roots Protect evergreens with screening Use anti-desiccant if needed Wrap trunks to protect and remove in spring Use safe ice-melting products

The End