Invasive pests on trees and ornamentals

Invasive pests on trees and ornamentals

In the last few years, several very devastating pests have arrived that infest specific plants in various locations throughout the USA.  The list includes the ficus whitefly in Florida; the hemlock woolly adelgid in hemlocks throughout the Appalachian mountains, now spreading to surrounding areas; emerald ash borer in the great lakes states spreading out as far as Tennessee, Missouri, Maryland and by the Hudson river in New York; chili thrips in Texas and other warm climates; marmorated stink bug in the Eastern US across many Midwest states; myoporium thrips in California; and others.  There is also a royal palm bug and a red palm mite that suck juice from the fronds of palm trees.  As travel and international trade continues these invasive pests will continue to invade.  This blog writer will write about some of these pests individually as the season progresses.

These pests arrive with a susceptible host plant or plants that have no resistance to a place where there are no natural predators to keep the population under control.  Ficus, or fig, hemlock, and ash trees are being killed causing heavy financial burdens to homeowners and cities who have to pay to treat or remove these dead trees.  People like trees in their yards and trees lining the streets to keep the neighborhoods fresh, cooled, and beautiful.  Trees cool the environment and shade our homes to lower air conditioning costs.  Losing the trees can reduce the value of the home.  From my youth, I loved climbing trees and climbed as high as possible until I no longer trusted the small branches to hold my few pounds of weight.

What do homeowners do to care for trees that are infested?  Number one choice of many is nothing.  Yes, you can do nothing and with ficus white fly, hemlock woolly adelgid and emerald ash borer, your tree will most likely become infested and after three to five years will die.  Then it will either fall down in a few more years or you will have to cut it down.  Trees falling can injure people and cause damage to nearby cars, homes, and other trees and shrubs.  Cutting trees down on your terms is always better than letting nature put the tree down.  The second choice is to treat the tree to kill the invading insect and save your tree.  Research has shown that you can treat the tree yourself or have it professionally treated with similar positive results.  Get the tree treated before it has declined by 40% or more and your chance of saving the tree is very high. 

Professionals may spray the tree with a high powered spray to kill insects on the outside of the tree that suck juices from the tree -  like ficus white fly and hemlock woolly adelgid.  These types of sprays may also coat the tree trunk and leaves and leave a residual spray that will kill new insects that land on the trunk or leaves for a period of time.  The second type of professional treatment is to drill holes into the tree trunk at the base and inject insecticides into the tree.  When the insect chews or sucks juice from the tree, it gets a lethal dose of insecticide and dies. 

Homeowners rarely have the type of sprayer that allows them to spray higher than about 15 feet.  Many of the insecticides used by professionals can be purchased by homeowners and used with similar results.  These can be applied by drenching or placing granules near the trunk of the tree and watering it into the soil.  These products are very effective when insects drill into the tree and eat the cambium layer.  Research has shown these applications can be just as affective as professional applications.  The cost of these pests on a mature tree may be $1500 for tree removal, $200 for a professional treatment or $20 to $40 for do-it-yourself treating. 

What would a homeowner use?  Several companies provide products.  Imidicloprid is widely used under several product names.  Those names include several brands from Bayer Advanced with the Merit brand, Bonide, Green Light and others usually with Tree & Shrub in the brand name.  Green Light markets a unique product with dinotefuran brand named Safari.  Trade names with the Safari brand include Tree & Shrub with Safari, Emerald Ash Borer Killer and Rose & Flower with Safari Insect Control.  Both imidicloprid and dinotefuran effectively control insects.  Safari gets into the tree or shrub fast because it has higher water solubility and lasts for several months in the tree.  Imidicloprid takes longer getting into the tree, moves slower in the tree but lasts for a few months longer than Safari because it has very low water solubility. 

From a personal point, I have treated an azalea bush with Tree & Shrub with Safari that had skeletonized leaves.  Two days later a bunch of little green worms were all dead and laying on the ground under the bush.  Two red pine trees with woodpeckers attacking them for the insects were treated and both have stayed alive and are recuperating nicely.  One of the red pines had about 75% of the needles lost due to insect injury.  Another tree died before I treated the living tree and the insects had eaten the cambium layer under the bark.  These products are amazing at killing insects that attack trees and shrubs. 

If you live in an area with these insects, do treat your trees.  Doing so will save the tree and maintain the value of your property.

The Garden Doc