Though dogwood trees are, for the most part, an easy to care for landscaping tree, they do have some pests. The dogwood borer rarely kills a tree in one season, but if left unchecked, these pests can eventually kill a dogwood tree, especially a young dogwood tree. Keep reading to learn the symptoms of dogwood borers and dogwood borer control.
Most of the severe damage to dogwoods by this pest is caused by the dogwood borer larvae. Most often, dogwood borer larva will embed themselves in burrknots (lumps at the base of the trunk that were formed from undeveloped roots), in grafting collars, or in healed bark wounds.
If a wound, grafting collar, or knot becomes infested with dogwood borers, it may appear wet and will take on a reddish color. You may even see some bark fall away from these areas.
If the dogwood tree has a bad infestation of dogwood borers, there may even be large patches of healthy bark that will have a wet or damp look and may fall away from the tree easily.
Other symptoms of dogwood borers include wilting of new growth, oddly colored leaves, or leaves and branches that die off unexpectedly. In older trees that have been infested with dogwood borers for a long period of time, the bark higher up on the tree may crack and branches may break off.
Dogwood borer larvae are pink or light orange in color and are about 3 to 5 inches (8-10 cm.) long.
Good dogwood borers organic control starts with proper care of dogwood trees. Do not plant dogwood trees in harsh, full sun as this weakens the dogwood tree and makes them more susceptible to the dogwood borer larvae.
Dogwood borer larva are attracted to grafted dogwood trees, so either avoid grafted trees or keep a close eye on the base of these dogwood trees if you plant them.
Prune your dogwood tree at the proper time. Do not prune your dogwood trees from April until June, as this will leave open wounds during their most active time, which attracts the dogwood borer.
Keep the base of your dogwood free of weeds where the dogwood borers can hide and be careful not to damage your dogwood tree with weed whackers when removing weeds. It is best to simply keep the base of your dogwood tree well mulched. This will not only keep weeds away from the base of the tree, but will keep moisture in the soil, which will make the tree healthier and better able to fight off dogwood borer larvae.
If your dogwood tree becomes infested with dogwood borer larvae, proper dogwood borer control is to treat the base of the tree with insecticide in May. This is when the dogwood borer is most susceptible to dogwood borer insecticide. If you discover a dogwood borer infestation earlier or later than this, however, and you would like to treat it immediately, you can. It will not be as effective, but will help reduce the number of dogwood borer larvae, which will reduce the amount of damage to the tree until you are able to treat the dogwood tree with dogwood borer insecticide.
If a dogwood tree is badly infested, it may be best to remove the tree to prevent it from infecting other dogwood trees in the area.
While dogwood borers can become a serious problem, once you know how to treat for dogwood borer larva and damage, it becomes much less damaging to your dogwood trees.
Borers are the larvae of certain moths and beetles that feed on the wood in trees instead of the leaves or fruits. Borers tunnel into the woody parts of trees, including the trunk, twigs, branches and even the roots. Borer infestations in fruit trees are difficult to control, and insecticidal sprays are only effective during limited times of the borer’s life cycle. Several other methods exist, however, to control borer infestations in fruit trees.
Look for signs and symptoms of a borer infestation. Study the fruit trees for tunnels that larvae have made in the trunk and limbs. Also look for dying branches.
Apply an insecticidal spray to the fruit trees once per month in the summer, following the application directions on the label. Use the insecticide only when the adult borers are active and laying eggs. The timing of insecticide use is crucial, because the insecticides won’t work on borer larvae, only on the adults and eggs.
Introduce biological controls to eradicate the borers. Trichogramma are small wasps that are parasites to more than 200 moth species, including borers. The wasps lay their eggs inside the borer eggs, and the developing Trichogramma feeds on the borer larvae.
Wrap the tree trunks with burlap or three layers of old newspapers. Wrap the fruit trees before the adult borers begin to emerge in the springtime. Make sure that you cover the tree from the ground to the lower branches and leave it on the tree for the first one or two seasons. Wrap any nearby young trees, even if they’re not infested, to prevent the adult borers from laying eggs on the bark.
Hand-worm the trees by digging the larvae out of their holes in the tree trunk and branches using a wire or knife. Look for the larvae in August and September. The larvae will be easier to find during this time, because the newly hatched larvae will cause sap to flow when they begin to feed. Seal the holes with tree paint immediately after removing the larvae.
Keep the fruit trees healthy and injury-free. Fertilize the fruit trees with an appropriate all-purpose granular fertilizer once per month to boost the trees’ strength. Water the trees once per week. If the tree is weakened by any other diseases, be sure to treat those as well.
Try pheromone traps to control peach tree borers, lesser peach tree borers and dogwood borers. You can also try whitewashing the tree trunks or painting them with a white, water-based latex paint to repel the adult moths or beetles.
Remove and burn any dead, weakened, infested limbs from the fruit trees. Always destroy the diseased wood that you’ve removed from the tree to prevent the pruned branches from becoming a breeding ground for the borers.
Although borers can attack healthy trees, they are more attracted to disease-weakened or injured trees. Be on the lookout for borer infestations if your fruit trees are weak from drought, disease or injuries.
I knew about the emerald ash borer and the damage they caused but didn’t know a lot. Life takes us in all different directions, and I was not focusing on this as an issue yet.
Admittedly, I may have also had an “it won’t happen to me” kind of attitude.
But my ignorance and complacency were a huge and very costly mistake.
And I don’t want to see you make the same mistake I did.
About a week ago, I noticed stripped bark on my ash tree that extended from roughly 2 feet above ground to at least 20 feet high on one side of the trunks.
I quickly looked it up only to find that it is due to an ash borer infestation.
The moment I realized what it was, I called a certified arborist because the inclination is to take these down.
But if there’s a way to save the trees, a certified arborist would be able to provide the right information.
One week later, and the damage extends around the whole tree affecting all of the trunks.
Black twig borer (Xylosandrus compactus) female preparing to bore into a twig of a susceptible woody host.
Lyle Buss, University of Florida, Bugwood.org
Hosts: Flowering dogwood, redbud, red maple, magnolias, willows, live oak, pecan, grape, and black gum are common hosts, though this borer is known to attack over 200 different host species. The black twig borer is an introduced species from Southeast Asia that entered Florida in 1941 and has spread upward along the coastline of Georgia, South Carolina, and North Carolina.
Symptoms: Wilting of twigs and branches usually becomes evident within one or more weeks after beetles enter the twigs. Generally, branches that are attacked are 7/8 th -inch in diameter or less. Entrance holes are small (1/32 nd of an inch in diameter, or about the size of a pencil lead) and are located on the underside of twigs and branches.
Cankers from ½- to 8-inches long are common around the attacked area on larger twigs where multiple female black twig borers have entered the twig. These twigs die from the point of infestation outward, as the resulting cankers disrupt water movement to the ends of the twigs. Since leaf death is rapid, the brown leaves may stay attached. Dark stains from the ambrosia fungus are found in the central pith as well.
Insect Life Cycle: Adult beetles primarily are active in the early spring, but cold winters may reduce black twig borer populations or slow insect development. Adult beetles overwinter in infested tree twigs and branches, and the adult females begin to emerge about the time dogwoods bloom. The females then re-enter new twigs and small branches, form their brood chambers or galleries in the stem pith, and then lay eggs. It takes approximately 28 to 30 days to complete the life cycle (from egg to adult) within the host plant. During the spring, all stages of the beetle are found within their galleries, and 10 to 15 beetles may develop within a single gallery.
A magnolia twig gallery of black twig borer (Xylosandrus compactus) with white fungal ambrosia on which they feed.
Forrest L. Oliveria, USDA Forest Service, Bugwood.org
The adult beetles also introduce spores of a fungus (Fusarium solani) into the galleries that grow to produce white fungal ambrosia on which both adults and their immature grubs feed. Unfortunately, this ambrosia fungus is a pathogen of trees, and as it spreads, the fungus clogs the xylem tissue of the twig, resulting in wilting and death of the end of the twig.
In anticipation of dogwoods bursting into bloom each spring, many states hold festivals to celebrate the event, some lasting as long as a month.
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