Winter Injury

1. Winter Injury Plant Material Maintenance

2. Temperature Fluctuation • Damage can occur from: • Rapid/extreme fluctuations in temp • Extended mild weather can de-acclimate plants, leaving them vulnerable to rapid temp drops

3. Low Temperatures • Use USDA Hardiness Zone Rating • Several mild winters can lull people to believe plant will be hardy. (Cutleaf Japanese Maple) • Plant marginally hardy plants in protected sites. • East side of building • courtyards

4. Frost Cracks Long cracks on the south-southwest side of thin barked trees Due to temp fluctuations between day and night; uneven contraction of the wood Ex European Linden, Red Maple, Norway Maple

5. Frost Cracks on Green Ash

6. Sunscald Injury • Very similar to frost cracks; damage is an elongated canker • Winter sun is lower in the southern sky • The 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

7. Sunscald on the SW side of a Chokecherry tree

8. More Sunscald Injury

9. Winterburn on Evergreens • Browning or scorched needles • Due to desiccation • Winter sun & wind dries leaves • Transpirational water loss • Replacement water unavailable (frozen) • Can apply an anti-desiccant to prevent injury • Reapply throughout winter

12. 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

13. Help Me!

14. 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

16. 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

18. 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

19. The End