Galls are abnormal vegetative growths on trees that result from the feeding and egg laying activities of various insects and mites. Chemical secretions from the adults while laying eggs as well as the saliva from the feeding larvae cause the plant to react abnormally.
The more common gall producers on trees are aphids, beetles, jumping plant lice, midges, mites and wasps. Each species causes a swelling of plant tissue that is characteristic on specific plant parts such as the stem, twig, leaf or petiole. Most often the gall is more readily identified than the gall producer. It is convenient to identify galls and their producers simply by noting where the gall is located and also the shape of the gall. Table 2 on page 43 of the Forest Health Guide for Georgia lists some of the more common trees that are frequently attacked by gall producers along with a description and location of the gall.
Generally galls are not life threatening to trees. Oftentimes the most drastic effects are premature leaf fall and dieback of several smaller branches.
On small trees, galls should be pruned and destroyed. Leaf and twig litter that is on the ground around the base of the tree should be raked and disposed of. A few of the common species are shown in the images included here.
For information on galls, see page 42 of the publication Forest Health Guide for Georgia. This publication is produced by the Georgia Forestry Commission.
Other galls include:
Galls on black cherry, Andy Boone, South Carolina Forestry Commission, Bugwood.org
Lace bugs get their name from the appearance of the area behind their head and wing covers. The area forms a lace like covering over the body of the insect. They are 1/8 to 1/4 inch in length and are partially transparent. Lace bug damage appears on the upper leaf surface as white to yellow chlorotic spots. The lower leaf surfaces will be cluttered with black spots and the old cast skins of immature lace bugs. Initiating control in the spring between March and May will reduce problems later in the season.
Merritt Melancon, news editor with the University of Georgia College of Agricultural and Environmental Sciences
Hulking above their neighbors in the Chattahoochee National Forest, Georgia’s century-old hemlocks are giants. But the relatively scarce trees are quickly being felled by the tiniest of insects — the invasive hemlock woolly adelgid.
Tiny pests, big problems
Hemlock Woolly Adelgid, Connecticut Ag Experiment Station Archive
The adelgid is a tiny, fluffy aphid relative that feeds by piercing the bark of hemlock trees and draining the contents of plant cells, which contain nutrients created by the tree during photosynthesis. Millions can live on one tree, and by the time they finish feeding, the tree no longer has the strength to transport water and nutrients from its roots to its branches. The pest first arrived in Georgia 10 years ago after moving south through the forests that surround the Appalachian Mountains.
To date, the adelgid has killed millions of hemlocks on the mountainsides and stream valleys of the Appalachians, from New England south to the Smokies and the north Georgia mountains. Once infested, a centuries-old tree can die within 3 or 4 years said Will Hudson, a forest entomologist with UGA Extension.
University of Georgia researchers are racing against time looking for long-term biocontrols for the nutrient-gobbling pest.They hope by preserving specimen stands of hemlocks with insecticides now, there will be enough trees left to aid in regenerating Georgia’s hemlocks once the bio-control agents are ready.
“We can’t just let a bug loose in the forest and hope it works. The requirements for testing and screening of a new biocontrol agent are — and rightfully so — really, really stringent, and it takes time. The hemlocks don’t have that time,” said Hudson.
Enter the Legacy Tree Project — a public-private partnership between UGA researchers, Valent USA, private tree care companies and several municipalities. The project’s goal is to preserve stands of hemlocks so they can regenerate once the woolly adelgid is under control.
While hemlocks make up a small percentage of the forest canopy in Georgia, they are vitally important to the forest ecosystem — especially around streams. The giant trees shade streams and stream banks and provide the cool waters that Georgia’s trout populations need to survive while sustaining the tourist economy that surrounds the trout.
In addition to the aesthetic impact of the loss of the largest trees in mountain forests, dead trees pose a threat of falling, making camping, hiking and even driving, risky.
Two solutions, one goal
The woolly adelgids can be controlled two ways. One way is through the development or discovery of biocontrol agents — predatory insects that eat adelgids, but leave the rest of the ecosystem intact. This is a painstaking process of trial and error, but will offer low-cost, long-term control.
The other method is to treat every hemlock in the forest to prevent or cure adelgid infestation. This would be prohibitively expensive, time-consuming, logistically implausible and possibly ecologically damaging.
Entomologists at UGA and the U.S. Forest Service, including recently retired UGA forest entomologist Mark Dalusky, have identified and released two predatory beetles. They hope these insects will be effectively control the adelgid without harming the forest, but neither beetle has reached the numbers needed to control the pest.
Saving trees now, so that they can be preserved later
UGA entomologists, north Georgia arborist and hemlock enthusiast Jann George and Legacy Tree Project founder Joe Chamberlin have teamed up for the effort.
Chamberlin’s company, Valent, helped launch the Legacy Tree Project in 2010 in a handful of Midwestern towns with the goal of saving ash trees from emerald ash borers. Thousands of trees were saved, and a framework for battling other invasive tree pests was developed.
Valent donates insecticide where landmark hemlocks are dying – like the Chattahoochee National Forest.
The insecticide, a dry powder mixed with water, is injected into the ground around the hemlock’s root ball and the tree slowly absorbs the material, which kills the adelgids and prevents new infestations.
“Nearly 100 percent of the chemical is absorbed by the tree, which means there is very little chance any will move into nearby streams or groundwater,” George said. “There is hope for biological controls coming down the line. But the only way to get your hemlock tree back to health, at this point, is to use chemicals.”
This is the first time that the Legacy Tree Project has worked on public land. George has worked with Young Harris, Clarkesville, Dillard and Sky Valley and saved between 10 and 15,000 hemlocks on private land.
“The problem of global trade and invasive species are here to stay,” Chamberlain said. “We only have so many well adapted native species of trees that we can rely on, and we need to maintain them. What we’re trying to do is build awareness about invasives and stimulate action to help protect native tree populations.”
For more information about the hemlock infestation in north Georgia and UGA’s research into stopping the pest, visit www.forestpests.org/.
The USDA’s Animal and Plant Health Inspection Service (USDA-APHIS) is calling on the public to help stop the spread of 15 invasive species dubbed “Hungry Pests.” These non-native insects, other animals, plants and diseases could devastate America’s crops, trees and plants, and are often unknowingly spread through human actions. To help get the word out, USDA-APHIS is deploying its Hungry Pests’ anti-hero, Vin Vasive, in a series of eerie videos that debut in April during Invasive Plant Pest and Disease Awareness Month.
“Hungry Pests have a tremendous impact on our economy, environment and public health,” said Osama El-Lissy, deputy administrator of USDA-APHIS’ Plant Protection and Quarantine program. “They have already cost the U.S. billions of dollars and threaten many aspects of our everyday lives – from the food on our tables, to the forests we camp in, to the flowers in our gardens. When people are out hiking, gardening and traveling this spring and summer, we are asking them to be extra vigilant.”
El-Lissy added, “We think Vin Vasive and the videos will help drive home the messages about how people can help to ‘Leave Hungry Pests Behind.’”
With the public as a crucial line of defense against Hungry Pests, USDA-APHIS is asking everyone to take a few simple actions that can greatly reduce the spread of invasive species. These actions are:
Don’t move untreatedfirewood.
Buy plants, including ones online, from reputable sources.
Don’t bring or mail fresh fruits, vegetables or plants into your state or another state unless agricultural inspectors have cleared them beforehand.
Declare all agricultural items to customs officials when returning from abroad.
Comply with agricultural quarantines.
Wash outdoor gear and tires free from dirt before leaving fishing, hunting or camping trips.
Clean lawn furniture and other outdoor items before moving.
Vin Vasive, a man-like figure made entirely of invasive species, will make dramatic appearances in a series of five, 30-second videos created to remind people what actions they can take to prevent the spread of Hungry Pests. The edgy, attention-grabbing videos – starting with the first video, which reminds people about the importance of not moving firewood – will be shared on Facebook and YouTube throughout spring and summer, a particularly vulnerable time for America’s agriculture and forests as a surge in outdoor activity increases the spread of invasive species.
USDA’s targeted 15 Hungry Pests are putting our agriculture, forests and food supply at risk. They include four moths (European grapevine moth, false codling moth, gypsy moth and light brown apple moth), three flies (Mediterranean fruit fly, Mexican fruit fly and Oriental fruit fly), three beetles (Asian longhorned beetle, emerald ash borer and Khapra beetle), two diseases (citrus greening, sudden oak death), the insect that spreads citrus greening (Asian citrus psyllid), one ant (imported fire ant), and one snail (giant African snail).
To learn more, go to HungryPests.com, or join the conversation on Facebook, www.facebook.com/hungrypests. The website includes photos and descriptions of the 15 Hungry Pests, an online tracker where federal quarantines are located and phone numbers to report signs of an invasive pest.
About USDA-APHIS
The Animal and Plant Health Inspection Service is a multifaceted federal agency with a broad mission area that includes protecting and promoting U.S. agricultural health, regulating genetically engineered organisms, administering the Animal Welfare Act and carrying out wildlife damage management activities. These efforts support the overall mission of USDA, which is to protect and promote food, agriculture, natural resources and related issues. To learn more about APHIS, visit www.aphis.usda.gov.
Original story by Sarah Lewis, student writer with the UGA College of Agricultural and Environmental Sciences
“April and September are good times to apply baits, once at the start of the season and toward the end to help control before they come back in the spring,” said Will Hudson, a professor with the UGA College of Agricultural and Environmental Sciences.
Fire ants are most active in warm weather. Fire ant season can last 10 to 11 months out of the year in the most southern areas of Georgia. Controlling ant colonies before they produce a mound is important. However, Hudson says that once a treatment program is in effect, timing is not all that important.
Baits and sprays
The general rule of thumb is if the area is one acre or less, don’t use baits. Re-infestation is more likely from colonies outside of the yard when baits are used.
One important thing to remember is the difference between ‘no mounds’ and ‘no ants.’ “There is a difference between eliminating ants and controlling them,” he said. “Baits do not eliminate ants because there is no residual control. A new colony can still come in and be unaffected by the bait laid down prior to their arrival.”
To eliminate mounds completely, apply baits every six months, Hudson said. “There will be invasion in the meantime, and you will still have fire ants, just not enough to create a new mound,” he said.
Hudson recommends treating lawns smaller than an acre with a registered insecticide in a liquid solution. This should rid the lawn of fire ants for one to three months. If you choose a granular product, measure carefully to be sure you apply the correct amount of material and get good, even coverage, he said.
The least effective treatment option for most people is individual mound treatments, according to Hudson. Treating mounds in general is going to be an exercise of frustration, and killing an entire colony by treating just the mound is a challenge, he said.
Minimal impact
Baits are considered to have minimal environmental effects for those who chose not to use hazardous chemicals. Once the bait is out, there is hardly anytime for anything to come in contact with it before the ants get to it.
Nonchemical options include using steam or boiling water. “We recommend using boiling water to treat a mound near an area such as a well where you do not want any chemicals,” Hudson said. “Using hot water is very effective, but the problem is you are not always able to boil the water right next to the area you want treated.” Carrying the boiling water can inflict serious burns, so extreme caution should be used when treating with this method.
There are products on the market that are approved by the Environmental Protection Agency and labeled as organic. Hudson says organic designation is a “slippery” definition. There is an official USDA certification and many states have their own set of regulations when labeling a product as organic. This labeling can mean the product is either a natural product or derived from a natural product. “While there are a few products that qualify as organic, with most baits the actual amount of pesticide applied is minimal,” he said.
Realistic expectations
Hudson says to be careful when choosing a product because the labels can be confusing, even deceptive, and it is difficult to make the right choice. For assistance in selecting a product, contact your local UGA Cooperative Extension agent.
“The most important thing to remember is that you need to be realistic in your expectations,” Hudson said. “If you are treating mounds, you need to be prepared. You are going to chase the mounds around the yard.”
For more information on selecting a control measure:
Elmer Gray, University of Georgia, Entomology Department
With this winter’s unusually cold temperatures, the question of how these conditions affect insects is sure to arise. It is of little surprise that our native insects can usually withstand significant cold spells, particularly those insects that occur in the heart of winter. Insect fossils indicate that some forms of insects have been in existence for over 300 million years. As a result of their long history and widespread occurrence, insects are highly adaptable and routinely exist and thrive, despite extreme weather conditions. Vast regions of the northern-most latitudes are well known for their extraordinary mosquito and blackfly populations despite having extremely cold winter conditions.
The question then arises, how do insects survive such conditions? In short, insects survive in cold temperatures by adapting. Some insects, such as the Monarch Butterfly migrate to warmer areas. However, most insects use other techniques to survive the cold.
In temperate regions like Georgia, the shortening day length during the fall stimulates insects to prepare for the inevitable winter that follows. As a result, many insects overwinter in a particular life stage, such as eggs or larvae. Many mosquitoes overwinter in the egg stage, such as our common urban pest the Asian Tiger mosquito (Aedes albopictus), waiting for warmer temperatures and sufficient water levels to hatch in the spring. Another technique is to take advantage of protected areas, as do adult Culex mosquitoes overwintering in the underground storm drain systems. Other insects overwinter as larvae or pupae in the soil, protected from the most extreme temperatures. However, this still doesn’t answer how insects survive freezing temperatures, only to become active as warmer temperatures return.
All insects have a preferred range of temperatures at which they thrive. As the temperature drops below this range the insects become less active until they eventually cannot move. A gradual decline in temperatures, coupled with a shortening day length, serves to prepare an insect to tolerate freezing temperatures. Several factors are important to this tolerance.
The primary thing that an insect has to avoid is the formation ice crystals within their body. Ice crystals commonly form around some type of nucleus. As a result, overwintering insects commonly stop feeding so as to not have food material in their gut where ice crystals can form. This reduction in feeding will also result in a reduction in water intake.
A degree of desiccation increases the concentration of electrolytes in the insect hemolymph (blood) and tissues. In addition, insects that can tolerate the coldest of temperatures often convert glycogen to glycerol. These electrolytes and glycerol create a type of insect antifreeze. This will lower the freezing point of the insect to well below freezing, a condition described as supercooling. When this occurs, the insect can withstand extremely cold temperatures for extended periods.
However, at some point insects will suffer increased mortality, possibly due to desiccation, toxicity or starvation. Nevertheless, insects are well adapted to survive freezing temperatures, especially after a few 100 million years to perfect their systems. It is generally assumed that introduced pest insects from sub- and tropical areas would be more susceptible to extended cold spells, but depending on their ability to find local refuges and their numbers and adaptability, they likely will remain viable and persist as pests as well.
In summary, entomologists don’t expect the cold winter to have a significant impact on insect populations this spring. Local conditions related to moisture and overall seasonal temperatures (early spring/late spring) will play a much more important role in insect numbers as we move from winter to summer and prepare for the insects that will be sure to follow.
Sustainable nursery and IPM practices videos are now available online!
University of Georgia and University of Florida have partnered to produce a series of short videos to help nursery producers to better understand and to more effectively use sustainable practices.
One of the latest videos covers Integrated Pest Management (IPM). The video includes an overview of IPM including sanitation, irrigation and sustainable pest management. See the IPM video here.
Is there an unwanted invasive insect or plant on your farm or in your garden that you don’t recognize? The University of Georgia College of Agricultural and Environmental Sciences has an app for that.
Invasive species trackers at the UGA Center for Invasive Species and Ecosystem Health have developed a suite of apps to help farmers, forestry personnel and home gardeners identify strange unwanted invasive pests. They can now identify their problem invasive pests in the field, rather than breaking away to sit down at a computer and look it up.
Apps developed by the center’s technology director Chuck Bargeron and his co-workers provide direct links to different databases specializing in informing and educating the public about invasive species, those not native to an area that has been introduced and causing damage to agriculture and forestry. Such species include the kudzu bug that munches on soybeans and the spotted wing drosophila which affects blueberry crops.
“For the IOS platform, we’ve had more than 25,000 downloads of apps. The most successful one was the first one we did which was for Florida, which was focused primarily on pythons in south Florida. It’s probably been the most successful because it had the most press coverage when it first came out,” Bargeron said.
The app is one of 17 the center has developed. It provides different apps for different parts of the country because, for example, farmers in the Western United States aren’t concerned with the same species that growers in the Southeast are concerned with. Working a regional perspective allows users to focus on species in their geographic area.
Bargeron and members of the Center for Invasive Species and Ecosystem Health have had great success with database web-based resources of information, especially after the pictures image archive were added to the website in 2001. When Keith Douce and David Moorhead, — co-directors of the center formally known as Bugwood Network, — launched the website in 2001 they added pictures from 35mm slides. Approximately 3,500 pictures were available. As more and more people began using the website and recognizing its value, they started sharing their own pictures. The database of pictures increased greatly in the 12 years since the website was started. Now, more than 200,000 pictures from more than 2,000 photographers are in the systems database.
These resources have also changed the way forestry and agriculture classes are taught. An entomology professor at Texas A&M told Douce the resources caused him to completely restructure how he teaches his classes.
According to Douce, the center website generated 9.3 million users last year and 260 million hits.
For more information, visit the website at bugwood.org.
Sharon Dowdy, News Editor with the UGA College of Agricultural and Environmental Sciences
Four mobile applications designed by University of Georgia specialists are putting lawncare information at your fingertips, literally.
The turfgrass apps created by UGA College of Agricultural and Environmental Sciences faculty make turf management in Georgia readily available. Turfgrass Management, Turf Management Calculator, Turfgrass Weeds and Turf Management Quiz can all be downloaded from the UGA Turfgrass Team website at www.GeorgiaTurf.com or straight to a mobile device through iTunes.
A lite version
The most popular UGA turfgrass app is Turf Management Lite. This free app was created with students, homeowners and professionals in mind. It includes photos of turfgrass varieties, pests, weeds and diseases.
Mobile applications, or apps as they are commonly called, can be downloaded onto smart phones like Droids and iPhones as well as portable tablets like iPads.
“Back in 2009, mobile apps were fairly new to smart phones. We saw a great opportunity to put the information where it can be easily accessed by mobile phone, iPods and tablets, instead of publishing a telephone-book-sized publication,” said Patrick McCullough, a UGA turfgrass specialist based on the Griffin campus. The turfgrass apps are his brainchild.
“Rather than have to go to the office and get an Extension publication or go online to view a publication, turfgrass professionals can now access the information they need in the field,” he said.
In-depth subscription version
There are three versions of the first app: Turf Management Lite, Turf Management Subscription and Turfgrass Management – Spanish. The lite and Spanish versions are free, but the subscription version costs $20 per year.
The subscription version includes everything from the lite version, plus information on pest control applications and a pesticide database. “You can search for trade names as well, and it includes PowerPoint presentations from UGA turfgrass faculty,” McCullough said.
The Spanish version is very popular in the turfgrass industry. “We have folks in the industry that speak Spanish as their first language. This app is a nice opportunity for those who are fluent in Spanish or primarily communicate in Spanish at work to have research-based turfgrass advice,” he said.
The Spanish version has been downloaded in more than 40 countries across the globe.
Making calculations easy
In 2011, the Turfgrass Management Calculator app was released. “It’s a comprehensive program that covers all types of applications, pesticide rates, fertilizer requirements, topdressing sand requirements, and calibration of sprayers and spreaders. Users enter known values of equations – like how much area is needed for a pesticide treatment at a certain rate. The app then does the calculation for you,” McCullough said.
College students majoring in turfgrass management use the app to double-check their math when learning these calculations, he said. “Some of these are very complex formulas. You can enter information for two products with different application rates and see which is more cost effective.”
The calculator app costs $5 and includes more than 16,000 pre-programmed calculations. It can also convert units from standard to metric. “It’s really a great tool for turfgrass managers and professionals, but students can learn a lot from it, too,” McCullough said.
Flash cards and quizzes
The Turfgrass Weeds app was released in 2011. It is designed to help users learn turfgrasses and weeds through a series of flash cards. “The cards reshuffle so users can continue to study and learn turfgrass species and weeds,” he said.
Just a few months ago, the UGA Turfgrass Team released its latest turfgrass app – Turfgrass Management Quiz.
“This app is a trivia style education game. You get test questions or photos with four choices to answer. You tap the correct answer, and when you’re done, you get a quiz score,” McCullough said.
The quiz app has two modes – quiz mode and study mode. Quiz mode scores your answers and study mode helps you get the correct answer.
“This app is perfect for students, but it can also be used by any turfgrass professional who wants to brush up on their knowledge. It’s a fun application that challenges you to get the best score, improve on your score and test your knowledge,” he said.
The new turfgrass apps are perfect for those who like to learn on their phones or mobile devices. UGA publications are also available online for computer users and in print form for those who still like the feel of a book in their hands.
“(Mobile apps) are a new technology – a new method to get information in the hands of the end user. We are trying to make it easier for people to get UGA turfgrass recommendations so it just makes sense for us to create these programs,” McCullough said.
To download the UGA turfgrass mobile apps or get more information on the turfgrass research at UGA, see the website www.GeorgiaTurf.com.
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)
