Winter weather — you know it’s coming, but there’s no stopping it. Even in the South, the impact of winter can take a toll, especially where poorly advised homeowners plant trees in USDA Zone 7 that are best suited for Zone 9. In the North, extreme fluctuations in temperature and moisture can wreak havoc with the survivability of valuable specimens. The question is, since it’s inevitable, how can we at least slow it down or lessen the effects?
The best way to address winter protection is with the mindset that it’s much easier to prevent than cure. Actually, this is also true for lots of tree maladies, including fungal infections, planting errors, soil compaction, irrigation equipment installation and most insect infestations. Putting toothpaste back in the tube after it’s been squeezed out, or in this case, water back into the tree after winter, is much harder than preventing it from being lost in the first place.
As we all know, there are many parts to a tree, all of which would benefit from protection, or at least, prevention of damage in winter. Many of these parts are seen — bark, leaves, trunk, limbs, flowers and fruit, and many are unseen — roots, heartwood, sapwood and cambium. In terms of protecting them, focusing efforts on three main tree structures will yield positive results:
- The goal for root protection is centered around hydration; we want them moist, not soggy or dry heading into winter. As summer turns to fall, and fall produces the glory of colors and textures that it’s known for, monitoring for soil moisture is a key stop in winter protection. While your customers’ kids are making piles of leaves and jumping in them in autumnal bliss, digging a few holes or simply poking a piece of rebar into the soil in various locations of the root system will provide a good snapshot of how moist the soil is at any given time.
- There are several reasons why soil moisture monitoring is important. First, most homeowners don’t know how to do it themselves, what “moist” actually means or where the roots are.
- Second, all the above-ground parts of the plant depend on soil moisture for continued hydration throughout the winter. Third, it allows the tree care provider an opportunity to strengthen the client relationship and provide instructions on how to water trees properly in fall.
- No question about it, watering trees in fall is more difficult than in spring and summer. In most cases, in mid to late fall, customers ask their sprinkler service provider to blow out their system to prevent damage from freezing of water in the lines once temperatures plunge into the mid 20s. Once the sprinkler system is nonoperational, one valuable tool has been removed, requiring watering to be done with hoses, temporary drip lines and ad hoc sprinklers drained after each use. These devices can be quite effective, but they’re less convenient to use.
Leaves and buds
- For most clients, leaves are the symbol of tree health they see every day. From a plant healthcare standpoint, leaves are only one of the many important tree parts, but certainly a very important one indeed. For deciduous trees, the focus is on the buds and new twigs as they contain tissues that are ready to push forth leaves and flowers for the following year. Fortunately, these are covered with bud scales that function to retain moisture. But in some severe winters, they may not be sufficiently thick to prevent desiccation. Conifers can lose water through two structures, the leaves/needles and buds. Again, windy days and cold temperatures can accelerate the drying of essential tissues.
- Two main methods can be utilized for preventing loss of hydration in leaves and buds: the previously mentioned soil moisture monitoring and watering, and applications of anti-desiccant products to coat the needles with a light arboricultural wax in an effort to retain moisture. Though products may vary slightly in terms of application timing and length of protection, a time frame of every six week should be considered. If it helps with marketing, it can be tied to winter holidays, such as Thanksgiving, Christmas and Valentine’s Day. Be sure to read and follow all label directions when applying these products.
- Trunks are the sometimes overlooked “prone to injury” tree part. The most common injuries in winter are from rodents and sunscald. Mice, voles, squirrels and rabbits are often frolicking about in December and January, looking for something to eat. They find tree trunks, especially young ones, to be a tasty treat. Typically, they chew bark and cambium tissues, interrupting nutrient and water flow. Installing PVC collars are a good way to prevent this sort of damage.
- Sunscald occurs on sunny days in winter when the rays of the sun warm the outer bark layers, softening them and the cambium underneath, causing a dehardening of the tissue. The injury occurs when temperatures plunge into the teens and single digits after sunset, causing the moisture in the softened tissues to crystallize. When repeated several times over the winter, the bark and conductive tissues flake off and become nonfunctional.
- If painted a light color, white or beige, PVC collars work well to reflect winter sunlight and lessen the degree of the injury.
- During winter thaws, tree roots are especially susceptible to damage from compaction from heavy equipment; even normal-size trucks can impart sufficient compressing force to cause damage to roots. These types of damage are often hidden or removed in the memory of customers when trees fail to perform well the following year. They simply don’t see the cause and effect, as the length of time that has occurred between the compaction and the thinned canopy or stunted growth prevents them from considering it as a contributing factor. It’s the job of the tree care provider to remind them of possible causes when visual symptoms are observed in the growing season.
- One of the most dramatic influences in winter is wind damage. The forces of Mother Nature are often unpredictable and unrelenting. From a protection standpoint, it’s important to inspect tree crowns and branch attachments in late fall to note any suspect limbs and areas of concern. When observed, create a proposal to convince customers that action is needed to prune and stabilize defects to prevent them from further damage to the tree, the trees around them and from falling on valuable targets in winter.
- In regions of the country where snowfall is common in winter, trees that are in close proximity to sidewalks, streets and parking lots are susceptible to injury from being struck with a snow plow. The injury from being struck with a fast-moving truck with a snow blade is difficult for a tree to recover from, as bark, cambium and sapwood are usually ripped loose and dehydrate the tree in the process. Installing snow stakes in late fall can reduce the damage, but perhaps the most effective prevention technique is simple and straightforward conversation with the snow removal provider.
- In these same regions, ice melt products are commonly used to prevent pedestrians and vehicles from slipping on the ice and causing damage to their bodies and cars/trucks alike. Prevention of damage to trees from these materials isn’t easy, as the best (and cheapest) product to remove ice is caustic to cement and damaging to tree and shrub roots, as well. Less caustic options, such as calcium magnesium acetate, are less damaging but more expensive. Another option is to use less ice melt product and mix sand with driveway salt for traction. Of course, then the undesirable result is the need to sweep up the sand, as well as the possible negative effects of mixing sand with clay soils where tree roots are growing. Sand and clay mixtures are not desirable for root growth, as they provide less capacity for oxygen exchange, water penetration and root expansion.