Community and School Gardening in Georgia

Jean Williams-Woodward, UGA Plant Pathologist

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.

Sharon Dowdy, News Editor with the University of Georgia, College of Agricultural & Environmental Sciences

See the original article here dated Oct 21, 2010

Honey bee, Jessica Lawrence, Eurofins Agroscience Services, Bugwood.org

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.

For more information on Africanized honeybees, read this UGA Extension publication.

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.

Rose Rosette Virus – an emerging problem

Man’s death confirms presence of Africanized honeybees in Georgia