Q: Something is chewing off the ends of branches on some of my trees. I go out every morning and there are three or four more on the ground. The leaves are nice and green on the fallen branch. Is it squirrels or could it be something else?
A: What you are seeing is twig girdler damage. This is a long horned beetle (so named because his antennae’s are longer than his body). It is a pest of pecan and hickory, but may also attack persimmons, hackberries and other hardwood trees.
The nature of the girdle itself distinguishes the twig girdler from other branch pruners and why I can tell it’s not a squirrel. The cut by the twig girdler is the only one made from the outside of the branch. The cut end of the branch looks like mini beaver damage. Since the twigs are girdled while the leaves are present, the severed twigs retain the leaves for some time.
The adult beetles girdle twigs and small branches causing the ends to break away or hang loosely on the tree. It is not uncommon to see the ground under infested trees almost covered with twigs that have been cut off. The female lays her eggs in the tips of the branch then chews around the branch leaving a little wood attached in the center. This breaks off in the wind. If you look closely on the fallen branch you will see tiny holes where the eggs were laid. The holes will usually be by a bud scar or near a side shoot.
They aren’t hurting the tree unless you had a pecan orchard, then the loss of branch tips could reduce nut production in the following few years. Most girdled twigs are from 1/4 to 1/2 inch (occasionally up to 3/4 inch) in diameter, and 10 to 30 inches long.
The best control is to pick up the twigs and discard them as the larvae develop and pupate in them. Insecticide is rarely justified or practical.
(Editor’s note – squirrels can also clip off limbs but the cut ends will look chewed or broken)
Editor’s note – The recent bee kill in Oregon and the resulting statewide temporary restriction of one of the neonicotinoid insecticides highlights the need to be careful in timing neonicotinoid insecticide applications and using these pesticides safely.
Many homeowners may grimace at the sight of grubs, caterpillars or other pests lurking in their lawns, but understanding when and how to apply an insecticide to control these pests could have a big impact on native pollinator populations, according to a researcher from the University of Kentucky College of Agriculture, Food and Environment.
Jonathan Larson, a UK doctoral student, has found that when neonicotinoids, a type of systemic insecticide, are applied to flowering lawn weeds that are frequented by native bees, such as dandelions and white clovers, the chemicals can negatively impact local pollinator populations.
While honeybee population decline has received much attention, bumblebee numbers have also been on the decline. Much like honeybees, bumblebee population decline is related to diseases, pesticides and habitat loss or fragmentation.
“With honeybee populations struggling, we need to rely on native bees, such as bumblebees, to pick up the slack on plant pollination,” said Dan Potter, UK entomologist and Larson’s adviser. “Many native bees are much more efficient at pollinating certain types of crops, like tomatoes, urban flowering plants and vegetables grown in home gardens.”
Larson’s research, published in the journal PLOS ONE, showed that exposure to clothianidin, a neonicotinoid insecticide, negatively affected queen production. It also slowed foraging and caused higher mortality rates in worker bees within five days after exposure at plots on UK’s Spindletop Research Farm compared to control hives. When moved to an untreated field to forage for six weeks, the bees had a hard time gaining weight compared to the controls. Bumblebees exposed to chlorantraniliprole, from a relatively new class of lawn insecticides, developed and reproduced normally compared to the control hives.
“We’re trying to figure out ways that people can safely use insecticides and not affect native pollinators,” Larson said. “One way may be for homeowners and commercial lawn care professionals to use the newer class of insecticide instead of a neonicotinoid to control common lawn pests. Another way could be mowing treated areas.”
He found that when clover flowers treated with an insecticide are removed by mowing and new flowers grew to replace them, neither insecticide adversely affected bumblebee colonies.
“Direct contamination of the flowers is the problem, so homeowners need to remove the flower heads of weeds either before or after applying an insecticide to prevent exposure to native pollinators,” Larson said.
Larson is now studying the level of insecticides present in the nectar of subsequent generations of clover flowers after the field has been treated with an insecticide and the treated flowers have been removed.
Sandi Martin and Merritt Melancon, University of Georgia
For years foresters and invasive insect experts have been on the lookout for the arrival of an unwelcome guest in Georgia. Now that it’s here, they hope the public will help restrict its spread within Georgia.
The small, iridescent-green beetle has killed millions of ash trees across a wide swath of Canada and the upper Midwest since it was first detected in 2002. The emerald ash borer — Agrilus planipennis— has spread south and west from infested areas over the last decade.
In July, researchers found adult emerald ash borers in survey traps in DeKalb and Fulton counties. A follow-up ground survey found larvae in nearby ash trees, confirming an established emerald ash borer infestation.
Since 2005 University of Georgia invasive species experts have conducted an extensive trapping program in Georgia to screen for the emerald ash borer.
Georgia’s five species of native ash trees usually grow along stream banks. While ash only makes up about 1 percent of Georgia forests, they play an integral role in preventing the erosion of stream banks and keeping silt out of natural waterways. Ash is also a popular landscape tree, with 2.9 million trees planted around Georgia homes, businesses, parks and greenways. The value of these city trees in Georgia is estimated to be around $725 million.
Although the adult beetle is an active flyer, it is believed that the primary way the beetle spreads is by hitching a ride on infested ash firewood, logs and nursery stock. Emerald ash borer larvae kill ash trees by burrowing serpentine tunnels in the inner layers of bark, preventing the tree from transporting water and nutrients to and from the tree canopy.
The Georgia Invasive Species Task Force will launch a public outreach plan to try to curb the spread of this pest in the near future. This task force consists of the Georgia Department of Agriculture, the Georgia Forestry Commission, UGA, the Georgia Department of Natural Resources and the USDA Animal and Plant Health Inspection Service.
People can help slow the spread of this beetle through Georgia by not moving firewood and by helping others to understand how dangerous it can be to move firewood from one area to another.
“To prevent the spread of emerald ash borer, it is important not to move firewood in which the insect can hide,” said Kamal Gandhi, associate professor in the UGA Warnell School of Forestry and Natural Resources. “Buy local firewood, whether camping or for your home.”
To help reduce the spread of the emerald ash borer in Georgia, homeowners with ash trees should have a certified arborist check their trees for signs of emerald ash borer infestations.
Suspected infestations should be reported immediately so that foresters or arborists can understand how the infestation is spreading. This will aid in the development of effective methods to reduce its spread and impact.
“The faster (scientists) can track the spread of the insect, the faster they can work to stop it,” said Joe LaForest, integrated pest management and forest health coordinator at the UGA Center for Invasive Species and Ecosystem Health.
Emailing one of the Experts listed below; or by contacting a representative of the Georgia Forestry Commission, Georgia Department of Agriculture, the Department of Natural Resources or their local UGA Cooperative Extension agent.
For more information about spotting signs of emerald ash borer infestations, watch this.
(Sandi Martin is the public relations coordinator with the University of Georgia Warnell School of Forestry and Natural Resources. Merritt Melancon is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)
In an ongoing effort to protect bees and other pollinators, the U.S. Environmental Protection Agency (EPA) has developed new pesticide labels that prohibit use of some neonicotinoid pesticide products where bees are present. (This announcement affects products containing the neonicotinoids imidacloprid, dinotefuran, clothianidin and thiamethoxam. – Editor’s note)
“Multiple factors play a role in bee colony declines, including pesticides. The Environmental Protection Agency is taking action to protect bees from pesticide exposure and these label changes will further our efforts,” said Jim Jones, assistant administrator for the Office of Chemical Safety and Pollution Prevention.
The new labels will have a bee advisory box and icon with information on routes of exposure and spray drift precautions. Today’s announcement affects products containing the neonicotinoids imidacloprid, dinotefuran, clothianidin and thiamethoxam. The EPA will work with pesticide manufacturers to change labels so that they will meet the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) safety standard.
In May, the U.S. Department of Agriculture (USDA) and EPA released a comprehensive scientific report on honey bee health, showing scientific consensus that there are a complex set of stressors associated with honey bee declines, including loss of habitat, parasites and disease, genetics, poor nutrition and pesticide exposure.
The agency continues to work with beekeepers, growers, pesticide applicators, pesticide and seed companies, and federal and state agencies to reduce pesticide drift dust and advance best management practices. The EPA recently released new enforcement guidance to federal, state and tribal enforcement officials to enhance investigations of beekill incidents.
R. G. Van Driesche1, J. LaForest2, C. Bargeron2, R. Reardon3 and M. Herlihy1
1University of Massachusetts, PSIS/Entomology; 2University of Georgia; 3USDA Forest Service, State and Private Forestry
The photos present in this publication are intended to help foresters, urban landscaping employees, or others working with trees recognize some of the common pest insects affecting trees in North America and understand their life cycles and how they damage trees.
Remember that big green worm with the red horn on its tail that was eating your tomato plants in July? Well, over the last month it has burrowed into the soil, pupated, and emerged as a big moth that shows up after sunset and feeds from flowers at night.
The moths are called “hummingbird moths” because they look and act so much like hummingbirds, being able to hover over a flower and drink from it in flight. Also, like hummingbirds, they are fast fliers, zipping back and forth among blossoms. The moth’s tongue is actually longer than its body, allowing it to extract nectar from deep-throated blossoms.
Photo by Nancy Hinkle, UGA Entomologist
Photo by Nancy Hinkle, UGA Entomologist
Photo by Nancy Hinkle, UGA Entomologist
These hummingbird moths, which are also called sphinx moths, can have wingspans up to 4 inches. The moths are gray with darker gray and black markings, and they have yellow or orange spots on the sides of their abdomens.
The moths’ larvae, those green caterpillars known as hornworms, feed on Solanaceous plants like tomato and tobacco. They have also been found on potato, eggplant and peppers, and they can thrive on these plants’ wild relatives such as jimsonweed, tropical soda apple and horse nettle.
Tomato hornworms and tobacco hornworms are similar in appearance and behavior, and both feed on tomato and tobacco plants.
The larvae are harmless to humans; the red horn on the rear end is flexible and cannot stick you. The best way to manage the pests is to be vigilant and pick each caterpillar off the plant as soon as you see it. Save it, and you can give it to a local schoolteacher for classroom demonstrations.
After the larva has fed to fullness, and is about 3 or 4 inches long, it crawls down into the soil and changes into the pupal stage. The pupa is distinctive in having a loop, almost like a shepherd’s crook, at one end; this is where the mouthparts of the adult moth form.
The reddish-brown pupa will remain underground until next spring when the adult moth will emerge from the pupal skin, through the soil and start the cycle all over again. If your garden is already planted when these moths emerge in the spring, they may lay their first batch of eggs on your young tomato plants, so keep an eye out for hungry caterpillars.
Rose rosette virus is a damaging disease that is seeing an increase in occurrence across midwestern and southern states. Rose rosette has been described since the 1940s, but it wasn’t until 2011 that the causal agent was confirmed to be a virus spread by the ‘rose leaf curl’ eriophyid mite (Phyllacoptes fructiphylus).
Rose rosette virus was predominantly found in multiflora roses (Rosa multiflora) that now grow wild in many places and is considered an invasive/noxious weed. The wild multiflora roses were thought to be how the mite and virus spread into rose landscape plantings. What is causing greater concern is that the virus is now being seen in Knock-Out roses (see images). Knock-Out roses cover commercial and residential landscapes throughout the south because they are more disease resistance than other hybrid roses. The presence of the mass Knock-Out plantings provides an easy means for the mite and virus to spread from plant to plant and location to location. The increase in the amount of rose rosette showing up in Knock-Outs, which are all vegetatively propagated, has led to speculation that the virus may be spreading through nursery stock as well. This is possible, but currently I don’t have any evidence of this.
Symptoms of rose rosette virus mimic herbicide injury. In the past, we had no way of confirming the pathogen’s presence and often tried to rule out improper herbicide use. Symptoms include an increased and rapid elongation of new growth; abnormal reddish discoloration of shoots and foliage (see image above); witches broom (proliferation of new shoots); an overabundance of thorns; and deformed buds and flowers.
We are testing a molecular PCR test in the Athens clinic that can detect the virus RNA in order to confirm the disease. This test is the only way we can confirm virus infection.
If rose rosette virus is confirmed or suspected, control options are few. There is no cure for rose rosette. Roses growing near infected cultivated or wild (multiflora) roses have a high risk of infection.
To prevent infection:
Inspect new nursery stock for symptoms of infection.
Remove all multiflora roses from the area and increase plant spacing so rose plants will not touch each other to reduce mite spread.
If rose rosette is present, completely remove the infected plant by bagging and discarding or by burning.
There is some discussion on online garden forums and from rose breeders that just pruning off symptomatic canes/stems will remove the virus. There is not at present any scientific evidence that this will work. Therefore, the prudent recommendation I can give is to completely remove the infected plant.
A miticide can help reduce mite (and virus) spread; however, miticides labeled for spider mite control and those commonly packaged for homeowners are ineffective on eriophyid mites. If homeowners want to have their roses sprayed, then they should contact commercially licensed landscape professionals who can use (per communication with entomologist Will Hudson) Avid (or other abamectin generics), Floramite, Magus, and Forbid.
Last week’s death of an elderly Dougherty County man has been attributed to Africanized honeybees. This fatality confirms the bees’ arrival in Georgia, according to the Georgia Department of Agriculture (DOA).
“The victim was operating a tractor and mower, aggravated a nest of bees and received more than 100 stings,” said Keith Delaplane, a University of Georgia Cooperative Extension entomologist.
Africanized honeybees have been in the United States since October 1990 when they were found in Texas. In 2005, they were confirmed in Florida.
European cousin essential to crops
A sub-species of honeybee, Africanized honeybees can interbreed with the European honeybee that is well known throughout Georgia as an important pollinator and producer of honey. One-third of American diets contain food crops that rely on European honeybees for pollination, according to the Georgia DOA.
Africanized and European honeybees look and behave alike in some respects. Each bee can sting only once, and there is no difference between Africanized honeybee venom and that of a European honeybee.
However, “the African variety is extremely defensive and responds with a massive stinging reaction with little provocation,” Delaplane said.
Run, don’t swat, and get inside and stay inside.
The UGA honeybee expert urges the public to become aware of how to react if Africanized honeybees attack. He offers the following lifesaving tips:
1. Be cautious around places where Africanized honey bees are likely to nest, such as abandoned sheds, bee hive equipment, discarded tires and underground cavities.
2. If you are attacked, RUN AWAY. “You may think this sounds silly, but experience has taught us that people don’t run away,” he said. “Instead, they stand and swat, which simply escalates the defensive frenzy until it reaches lethal proportions.”
3. Get inside a closed vehicle or building as fast as possible, and STAY there. “Here’s another hard lesson we’ve learned. People don’t stay inside a closed vehicle if a few bees follow them inside,” Delaplane said. “Instead, they panic and flee back outside where tens of thousands of angry bees attack them.”
This pattern has repeated itself over and over in the stinging incidents entomologists have monitored in Latin America and the southwestern U.S., he said. “The lesson is, don’t worry about the few bees that follow you indoors. Get inside, and stay inside.”
4. European honeybees and beekeepers are our best defense against Africanized honeybees. “Some communities may be considering zoning restrictions against all forms of beekeeping. This essentially cedes territory to the enemy. Only gentle European bees can genetically dilute or out-compete the defensive Africanized variety,” he said.
First aid tips
If stung, the Georgia DOA says to follow these steps:
• Scrape – do not pull – stingers from skin as soon as possible. Pulling the stinger out will likely cause more venom to be injected into the skin.
• Wash sting area with soap and water.
• Apply ice for a few minutes to relieve pain and swelling.
• Seek medical attention if your breathing is troubled, if you’re stung numerous times or if you’re allergic to bee stings.
Additional information about animals and Africanized Honeybees (AHB) from Dr. Nancy Hinkle, UGA Veterinary Entomologist.
Note that animals in the area (essentially the neighborhood, since AHB will attack in a large area when provoked), such as horses, dogs, cats, livestock, etc. should be taken indoors and protected from bee attack while any AHB control efforts are undertaken. Some of the most heartrending tragedies have occurred when kenneled dogs were attacked by AHB after the bees were disturbed by nearby human activity.