Ornamental Pear trees have been recently under attack from a hard to treat fungus known as Trellis rust. Originally from Europe, Trellis rust or European Pear Rust is caused by the rust fungus Gymnosporangium sabinae. The disease may present a serious health threat to members of the Pyrus species, including both ornamental and fruit pear types. Ornamental Pear trees have been popular trees planted for decades noted for their fast growth rate, tolerance of urban conditions, fairly compact shape and white blooms that appear in early spring. Unfortunately, hundreds of trees have been noted dying in Rockville Center and the disease has been spreading to the Nassau and Suffolk County areas of Long Island. The fungus has spread from the mid-western states to upstate New York and Connecticut over the past several years and seems to be getting progressively worse. According to horticulturists, part of the problem is that the trees have been over-planted, resulting in a rapid spreading of the disease.
Symptoms to look out for are yellow-orange leaf spots (see photograph), which develop into spores in late summer. The spores can be spread to other host plants by wind or to the roots if the trees are close enough together. The secondary host during the winter months is juniper, allowing the fungus to survive when the pear trees drop their leaves; hence, continuing the cycle in the spring.
If you spot damage on your tree, remove and destroy the infected leaves to prevent spores from spreading. If caught early enough, systemic and spray fungicides can be applied to inhibit the spread of the disease. Best preventive measures are to be alert in monitoring your trees, and when in doubt, call a tree professional.
What is “winter bronzing”? While approaching the end of winter, some of your favorite evergreens may appear to take on a bronze appearance. You may be wondering. “Is this normal or is my plant dying?” Changing foliage color is a normal phenomena that affects some evergreens near the end of winter while seasons are transitioning. Freezing temperatures, followed by a warming trend, longer hours of sunlight, then more cold can trigger foliage to discolor. The color change is a reaction to low temperatures, winds and sunlight, causing mild desiccation of the needles or leaves, allowing the underlying colors to show through. This dulling of green foliage is more pronounced on plants that receive more sunlight. The result is commonly known as “winter bronzing”. The longer the ground is frozen and the more water that is evaporated from the plant than it can take in, the more pronounced the foliage will appear to turn from green to brown, bronze, or even orange or purple. This process is similar to why deciduous leaves change color in the fall. While the tree is going dormant for the winter months, chlorophyll production subsides and the true underlying colors of the leaves are revealed.
When can I expect my trees to look more normal? Once the temperatures rise and new growth is stimulated, the foliage will turn back to a more vibrant green. Broken or dead branches are different in that they are completely dried out and brown. Those branches should be pruned off the tree in late winter/early springtime to prevent any further damage. Any falling or divided tree leads can be arbor tied to secure them and encourage upright growth. Split branches can also be arbor tied together, and if caught in time the cambium growing layer of the tree can mend. In the photograph above, the center upright Western Arborvitae are displaying signs of bronzing with no evidence of any completely browned or broken branches, both indications of a normal and healthy tree.
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The seasons have been shifting in the northeast, leaving many homeowners in much dismay when it comes to winter garden maintenance. Winter storms can hit late winter into early spring, causing more distress to plantings once they have experienced warmer than normal temperatures. As we await another winter storm, there are some precautions you can take to ensure the vitality of your landscape plants and protect them from possible damage.
SNOW WEIGHTED TREE BRANCHES: Most evergreen trees and shrubs can handlesnow build-up on their branches, but in the instance of a heavy snow, the branches may become weighted down. Certain Arborvitae are susceptible to the weight of snow pulling down on them and may have already experienced sagging branches. Further damage can easily be avoided by wrapping the branches together with arbor tie. The cloth tie cannot be seen from the outside, will prevent future damage from another snow, and the tree will look unscathed.
BROKEN OR DAMAGED TREE BRANCHES: Before an approaching storm, try to walk outside and inspect trees and shrubs on your property for any broken or damaged branches. If you do spot a damaged branch, tie the two split halves together by wrapping them tightly together with arbor tie. Start by wrapping the two halves tightly together and continue wrapping above and below the crack for extra support. If caught in time, the cambium (or growing layer) of the plant will repair itself and fuse the two parts of the damaged branch together. I have personally saved split branches on holly, azalea and arborvitae using this technique and the plants have recovered beautifully. Identifying these issues now and tending to them prior to the snow can mean the survival of your plant.
SNOW REMOVAL: While it is tempting to go outside and start removing snow from weighted branches it is also a good time to exercise caution. Under the snow-covered branches could also be a frozen layer of ice. Any manipulating of the frozen branches could result in easy breakage and permanent damage to your tree. A helpful tip is to very carefully dig snow from around trapped branches and allow them to spring back up on their own. Never shake branches with ice. It is best to let nature take its course and allow thawing to occur. The branches will gradually regain their shape as the ice melts preventing any harm to your landscaping.
SPRING BULBS AND SNOW: Just as your spring bulbs are emerging, a late winter snow storm in March can cause much distress and uncertainty. Besides having to tend with the snow, there is some reassuring news! While mulch protects dormant bulbs from cold, once they start blooming, a covering of snow will act as an insulator. The snow will help to hold in the natural warmth from the soil and provide protection. Once the snow is gone, you can continue to enjoy your bulbs!
As mentioned previously, plants are very resilient, and with a little care can bounce back and recover nicely after a major snow. With a March snow on the way, warmer days may not look promising at the moment, but Spring is right around the corner!
Dormant Oil is a known application that is sprayed on landscape trees and shrubs in fall to help protect them from overwinter damage from insects. Prepared from a mixture ofhighly refined petroleum oils combined with an emulsifying agent, dormant oil can be mixed with water and sprayed on trees killing exposed insects and mites by either suffocating them or destroying internal cells. These oils are effective in controlling most species of scales and mites that overwinter as nymphs or adults such as cottony maple scale, obscure scale, euonymus scale and lecanium scale which can do early damage. Dormant Oil is also effective on insect eggs that are laid in September and overwinter such as aphids, leafrollers, Spruce Spider Mite, Honeylocust Mite and European Red Mite. Dormant Oils are effective for both immediate and preventive care and have been developed to be less harmful to beneficial insects. They are also safe for birds, humans and other mammals.
When to Apply: Dormant oil applications should be applied in fall when temperatures remain in the 50’s at night (Early October) and must be done when temperatures stay above freezing for 24 hours. Dormant Oil is also best applied on a clear day with no wind and no threat of rain within a least six hours so that the oil can dry. It is preferable to choose a time when no rain is in the forecast for a few days to ensure effectiveness.
Warnings: Be sure to follow all label directions because oil sprays may damage certain plants, including Japanese maple, Eastern Redbud, sugar maple and Amur maple. It can also cause the foliage (needles) of Colorado blue spruce to become discolored (change from blue to green) since the pigment is formed from the oils on the surface of the plant. When in doubt consult with your landscape professional.
Dormant Oil when applied correctly will help to protect your trees and shrubs from winter and early spring harm from a variety of damaging insects and will ensure the health and vitality of your landscaping.
Recently I have been noticing a rash of trees that have become victim to the dangers of “volcano mulching”. Volcano mulching refers to the piling up of mulch around the base of trees causing moisture to build up around the trunk, rotting out the tree and leading to a slow death by suffocation due to lack of oxygen exchange to the roots.
Proper mulching involves adding a protective layer of organic mulch approximately 2-4 inches thick, keeping the mulch about six inches away from the base of trees so to avoid build up. Mulch has many advantages including the addition of organic matter to the soil, allowing moisture retention for the plant and helping as a weed barrier to keep weeds down as well as adding an attractive finishing touch to garden beds.
Signs of tree suffocation are indicated by a darkening of the trunk with patches of blacked spots going up the tree. In Photograph 2 you can see where approximately six inches of mulch had been piled up on this tree causing the tree to already start rotting. When removing the mulch it should be to the level of the tree collar (where the base of the tree starts to flare out). Even routine mulching can gradually build up so it is recommended to remove some of the older mulch if necessary before applying a new fresh layer. This tree should now be fine since the mulch was removed and the base of the tree will be allowed to heal and the health of the tree restored.