evergreen perennials in a shade garden under winter light (Photo credit: Wikipedia)
As we prepare for the upcoming winter, remember that winter is an excellent time for tree pruning – in fact, it is the preferred time to prune many tree species. During the winter months dead, dying and diseased limbs can be easily seen and removed. If you have been thinking about talking with your “tree guy” now’s the time to call. But there are some other reasons to get in touch with an Arborist this winter – winter drying and the associated cold weather damage can be addressed before it becomes a major problem.
Winter drying, winter injury and winterkill are synonymous terms applied to a foliage disorder common on evergreens in northerly climates. Winter drying typically occurs on warm, windy days following a period of cold (subfreezing) weather. Under these conditions, moisture loss through the foliage is greatly accelerated, while replacement of this water is restricted because the soil is either frozen or too cold to permit water absorption throughout the roots. Desiccation and subsequent death of the foliage often results. In severe instances, buds may also be affected leading to the death of twigs and entire branches. Shallow-rooted evergreens, which characteristically retain their lower branches, are very sensitive to winter drying. Recently transplanted evergreens – including broadleaved evergreens like Rhododendron, Holly and Azalea – are particularly susceptible to this disorder. The incidence of winter drying is greatest on poorly drained sites and in open, unprotected areas, which are subject to full sun and drying winds.
As usual, planting the right tree in the right place is the best way to help prevent this disorder. Judicious selection of plant species and planting sites is essential in preventing winter drying. Susceptible evergreens should not be planted on poorly drained sites or open, windswept areas. If you have already planted and think winter damage could be a problem, windbreaks either temporarily constructed with burlap or permanently supplied by living trees and shrubs can reduce the effects of drying winds. Application of anti-transpirants can also decrease the drying effects of wind and sun by restricting transpirational moisture loss. Consult with an Arborist before applying anything to your trees as anti-transpirants are not recommended for all species.
Some other things to consider before the real cold of winter sets in:
- Maintaining the vigor of ornamentals through fertilization, pruning and watering during dry periods is helpful in preventing this disorder.
- Ensuring that evergreens are well watered in late fall is particularly important.
- Mulch placed around susceptible species help slow soil moisture loss as well as restrict soil freezing.
I hope everyone is recovering from Sandy. As we start to leave fall and head into winter you may think your tree and shrub pest problems are over – well, think again! Yes, it’s true that most insect and disease problems are long gone by the time November and December roll around, but not all. Some problems are just getting started and for other conditions winter is the best time to treat them.
Scale insects can be a treated in the fall and winter. Many species of scale insects overwinter under a waxy coating for self-protection. They do not move during this stage in their lifestyle, but many will continue to feed if temperatures remain warm enough.
Spider Mites can also be a problem in the fall and winter. Some species are actually more active in colder weather – and these are usually referred to as cool season mites. Eriophyid mites and the Spruce Spider Mite both fall into this category. You should check all needle bearing plants, especially spruce and pine, for the presence of spider mites. Warm days – over 45 degrees following a period of cold weather is enough to “wake up” these pests and cause them to start feeding. This can often happen on plants near reflected heat and sun such as along roadways, at the corners of buildings and near windows.
The Hemlock Wooly Adelgid is another insect pest that will do damage during the winter. As with the above pests, late fall treatments and warm day inspections are the best approach.
Spend some time this fall with an Arborist and go look at your trees and make a plan for their health.
Today is day 2 of the NJ Shade Tree Federation annual meeting. A great couple of days where arborists and shade tree professionals can get together and learn from one another and from some guest speakers. With hurricane Sandy on the horizon, there sure is a lot to talk about.
How do trees get the nutrients needed to grow and stay healthy? As you all know, trees don’t “eat” – at least not in the typical sense, but they do consume and like all living things they need proper nutrition. Trees consume some basic raw materials and elements needed for growth and development from their roots, stems and leaves. The main source of water and chemical nutrients is from roots and the main source of carbon dioxide and other gasses is from the leaves. Trees, as with all green plants, are able to take sunlight and carbon dioxide, add some water and chlorophyll and make their own food. If trees can make their own food, why do we fertilize them? And, what is in typical tree fertilizer?
There is more to tree nutrition than just throwing some fertilizer on the ground. Among other things, trees need a healthy root system in order to absorb any fertilizer we throw at it and the soil pH needs to be correct. For a wide range of pH values, element availability for trees is adequate, but there are some specific pH requirements for certain nutrients to be absorbed and used by trees. Most homeowners try and have their trees fertilized each year; usually with an all-purpose fertilizer – But trees often need nutrients that are not in a standard store bought fertilizer preparation. If you really want to know what types of elements your trees need and if the pH is correct you should have a soil test done. Like a blood test, this will provide a reading of the areas that your tree may deficient in. The following elements are required in small amounts for the growth and development of healthy trees. These are referred to as micronutrients: iron (Fe), manganese (Mn) copper (Cu), zinc (Zn), molybdenum (Mo), and boron (B). Iron and manganese are required for chlorophyll production and photosynthesis. A deficiency results in yellowing between the veins, also known as interveinal chlorosis (see photo above – pin oak with a micronutrient deficiency). The other elements are need for the various physiological functions within a tree. Of course, all trees need the “macro” elements – N, P and K, but these are in most fertilizer preparations. (Note: recent research has shown the phosphorus is abundant in our soils of the Northeast and should not be included in fertilizer preparations).
Many elements are essential to tree life and each element has a unique job to perform in a tree. All of these essential elements are needed in different proportions. Too much or too little of any single element disrupts tree life. To determine the proper concentration of an element your tree needs and to determine the pH, soil samples should be collected and analyzed.
As you can see, there is more to fertilization than just putting some spikes into the ground. I highly recommend having a soil analysis done if any of your trees are showing decline symptoms. If the site is wrong for the plant – as in a high pH, all the iron in the world will not improve the condition of your tree. In that instance, you need to replace with a more suitable species or take steps to lower the pH.
My children often play a game asking me what my favorite color, or game, or food or whatever, is. I usually answer them and then I ask them: what is your favorite tree? They laugh and respond that they do not have a favorite tree. Well, as an Arborist and a Dendrologist, I do have a favorite tree – actually an entire Genus. I have always had a love for the Oaks (genus Quercus). Interestingly, when the National Arbor Day Foundation ran a campaign to vote for our national tree the oak was chosen over all the others. To me, oaks represent both strength and beauty – and a healthy dose of identification challenges! Here’s a short list to get you thinking.
One mention of concern: Many Oaks can be highly susceptible to Bacterial Leaf Scorch. This is a major threat to our Oak trees. Before you plant Oaks check with your Arborist about this disease.
Shingle oak – Quercus imbricaria Shingle oak is an excellent shade tree for a large area of land. Similar in shape to Pin oak, it can grow in non-acidic soils.
White oak – Quercus alba White Oaks benefit from large planting sites such as estates, parks and other large properties, but can do well on smaller sites with good care. White oak can be difficult to transplant so make your selection from a good source.
Sawtooth oak – Quercus acutissima Sawtooth oak has moderate water requirements and is drought tolerant. It also has moderate tolerance to salt and alkaline soils and likes full sun – what more could you want for a parking lot at the mall?? No wonder this species is showing up a lot in business centers and corporate complexes lately. I recently was attending an outdoor wedding and it was hot. Sure enough, one lone sawtooth oak was everyone’s place to get out of the sun.
If you have a favorite species or genus that you would like information on send me an email or post a comment.
Look at This: Enormous Whales Have Enormous (and Interesting) Poop
Biologists and Naturalists are always looking for interesting things in nature. I have a short lesson I do with my students on whale poop and it ecological role in the ocean. I’ll have to add this to my lesson.
Enjoy here’s the link
Nobody likes to hear it, but the end of summer is approaching. I live with the signs of nature so I tend to follow the year by what the trees and birds are doing. With the arrival of red winged blackbirds in late feb and early march I welcome spring and with the flocks of blackbirds flying overhead in the opposite direction this week, I know fall is coming.