The Landscape Alert is an email newsletter sent to the Georgia landscape and turf industry providing UGA information regarding industry issues.
These issues include emerging pests, regulatory changes, upcoming training, and new information, or technologies for the industry. Coordinated by the Center, the newsletter is a collaboration of several UGA departments – Horticulture, Entomology, Plant Pathology, Crop and Soil Science, and the Warnell School of Forestry.
Readers use the information contained in the Alerts for staff training, remaining current on upcoming issues, scouting for and identifying pests, evaluating current pest control practices and improving workplace safety. Alerts help maintain communications between state and county Extension staff, researchers, the industry, and industry associations. Alerts also serve as an educational tool for County Extension Agents.
Landscape Alerts are currently sent to more than 1700 readers and feedback has been very good. In a recent survey, of those responding, 93% stated they learned something they plan to use.
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Latest Landscape Alerts
Brown patch (caused by Rhizoctonia solani) and Pythium blight (caused by Pythium spp).
These diseases are often the most severe diseases for cool-season grasses, especially on tall fescue and ryegrass.
Pythium blight has the potential to cause significant damage to turfgrass quickly. The disease starts as small spots, which initially appear dark and water-soaked. Affected turfgrass dies rapidly, collapses, and seems oily and matted. White, cottony mycelia may be evident early in the morning. The disease is driven by hot-wet weather, which correlates with increased stress on the turf. Similar environmental and cultural factors that encourage brown patch also promote Pythium. Therefore, cultural practices for control of brown patch will also help to minimize Pythium blight development. A correct diagnosis is essential because Pythium control requires specific fungicides.
Several fungicides are available for each of the diseases described above. Consult the Georgia Pest Management Handbook or the Turfgrass Pest Control Recommendations for Professionals (www.georgiaturf.com) for proper fungicide selection and usage. Read the label and follow proper guidelines.
Pythium blight on tall fescue (Photo Lee Burpee)
Brown patch can cause a foliar blight, which results in necrotic leaves and circular brown patches up to 4-5 ft in diameter. High soil and leaf canopy humidity, and high temperatures increase disease severity. Higher than recommended rates of nitrogen in the spring promotes disease. Management options include: avoid nitrogen application when the disease is active, avoid infrequent irrigation and allow the foliage to dry, mow when grass is dry, ensure proper soil pH, thatch reduction, and improve soil drainage.
Brown patch on tall fescue (Photos Alfredo Martinez)
For more information on Brown patch and Pythium visit http://extension.uga.edu/publications/detail.html?number=B1233
By Alfredo Martinez
Gray Leaf Spot
Figure 1 (left) and 2 (right). Gray leaf spot on St. Augustinegrass (images by Alfredo Martinez)
Gray leaf spot (Figure 2) is a fungal disease that affects St. Augustinegrass, perennial ryegrass and tall fescue in Georgia. The disease is particularly aggressive in St Augustinegrass. Hot, humid summer weather and high nitrogen levels can make turf susceptible to this disease. The fungus causing the disease is Pyricularia grisea.
Symptoms: The symptoms of gray leaf spot vary depending on the grass cultivar. On St. Augustinegrass, gray leaf spot first appears as small, brown spots on the leaves and stems. The spots quickly enlarge to approximately ¼ inch in length and become bluish-gray and oval or elongated in shape. The mature lesions are tan to gray and have depressed centers with irregular margins that are purple to brown. A yellow border on the lesions can also occur. In cool-season turfgrass, the symptoms are similar to those of melting out.
Conditions Favoring Disease: Gray leaf spot is favored by daytime temperatures between 80ºF to 90ºF and night temperatures above 65ºF. It is also found in areas with high nitrogen levels and that are stressed by various factors, including drought and soil compaction. This disease is most severe during extended hot, rainy and humid periods.
Disease Management Tips: Management practices that minimize stress and avoid rapid flushes of lush growth during the rainy season lessen the likelihood that severe gray leaf spot symptoms will develop. If irrigation is used to supplement inadequate rainfall, water infrequently but deeply.
Proper irrigation regimens should protect against symptoms of drought stress without increasing disease pressure by extending periods of leaf wetness. Excessive soil moisture and leaf wetness promote gray leaf spot. Irrigating in the late afternoon or evening should be avoided, as this prolongs periods of leaf wetness.
Proper mowing practices are most important for gray leaf spot management in St. Augustinegrass. This grass must frequently be mowed during the summer months to remove excess leaf tissue and keep the canopy open and dry. Mow the turf at the correct height for the designated turfgrass species and remove only one-third of the leaf blade per mowing. Collecting clippings reduces the spread of the disease when gray leaf spot symptoms are evident. Thatch layers should be removed if they are greater than 1 inch in depth.
St. Augustinegrass is especially sensitive to some herbicides. If possible, manage weeds using cultural management techniques and minimal amounts of herbicides. The timing of any atrazine application should be chosen carefully, as this herbicide can stress the grass, especially when temperatures may climb above 85 degrees F. Atrazine applications made before or during disease-favorable conditions increase the likelihood of severe gray leaf spot symptom development. Spot-treating trouble areas with the herbicide may also be considered. Herbicides should always be applied according to the label instruction
Fungicides are available to control the disease. Consult the current Georgia Pest Management Handbook — www.ent.uga.edu/pmh/.
by Nancy C. Hinkle, Ph.D.
Dept. of Entomology, Univ. of Georgia, Athens
Anyone who has lived in Georgia probably has experienced ticks, either on themselves or on their pets. The most common of the state’s 22 native tick species is the lone star tick. The American dog tick is the next most frequently encountered tick; even though it is called a dog tick, it can be found on mid-sized wildlife of all types – coyotes, foxes, raccoons, opossums, etc. Gulf Coast ticks seem to be increasing in prevalence and expanding their range. Deer ticks are not very common (the ticks typically found on deer are lone star ticks).
But there is a chance that we’ll be getting a new type of tick – as if we needed it. Last year a tick species that had never been found in North America showed up on a farm in New Jersey. Despite control efforts and a harsh winter, it successfully overwintered and in 2018 has already been found in Virginia, West Virginia, Arkansas, and North Carolina. Its mode of distribution is unknown, but this rapid spread bodes poorly for containment.
Originally from northeast Asia, this tick showed up in Australia and New Zealand over 100 years ago, where it has established and become a significant problem on cattle and sheep. Known as the “Longhorned Tick” (scientific name Haemaphysalis longicornis), it is capable of transmitting several disease organisms infecting livestock and humans.
Why is this tick of particular concern?
- It is not native to North America. That means there are no natural controls here to keep it in check – no predators or parasites to suppress its numbers. Also, our animals have not developed any natural resistance to it, so it is anticipated to thrive on both wildlife and livestock.
- Males are extraneous. This tick is parthenogenetic, meaning females reproduce without mating, so males are unnecessary. Of course, this means that a single female transmitted into a new area can start a new population, indicating that infestations can readily spread. And each female produces over 2,000 eggs, so populations can rapidly explode.
- Longhorned Ticks do well on a variety of hosts, wildlife as well as livestock. They should thrive on white-tailed deer and quickly spread to livestock. They readily feed on small ruminants, horses, dogs, cats, humans, and several common wildlife species.
- This tick is tolerant of a wide range of environmental conditions, but will flourish in the Southeast, which has climate similar to its native range. As has been shown, it successfully overwinters in New Jersey, Virginia and West Virginia, so may well be active year-round in Georgia.
- The Longhorned Tick is capable of transmitting several animal and human pathogens. Large numbers of ticks feeding on an animal can produce anemia, particularly in young animals.
Unfortunately this invader looks like many of our native ticks, small and brown before it feeds, then swollen and gray after it takes a blood meal. So what should Georgians be looking for to alert them to the Longhorned Tick? High numbers of ticks per animal. Because each tick can produce over 2,000 eggs, tick populations expand rapidly and frequently exceed hundreds per animal. If you find an animal with lots of ticks on it, pull off at least a dozen, put them in a small bottle with alcohol, and take them to your county Extension office. Tell them to send them to Dr. Hinkle in Athens and we will identify them for you (be sure to include your contact information). Then treat the animals to kill the remaining ticks (consult the Georgia Pest Management Handbook for recommendations on tick control).
We may not see Longhorned Ticks in Georgia any time soon, but we do not want to miss them if they do show up.
Guest Post Written by Pam Knox,
Long-time residents of Georgia may remember the devastating floods of Tropical Storm Alberto in July 1994. The rain was so intense that Georgia’s one-day rainfall record was set during that storm, with 21.10 inches recorded at Americus for a 24-hour period ending on July 6, 1994, as the storm stalled over the state. In spite of that incredible record and the resulting damage, the National Hurricane Center did not retire the name of Alberto. This year, Alberto is the first name on the list of Atlantic tropical storm names for the season which begins on June 1.
The latest 5-day outlook for the Atlantic tropical region from the National Hurricane Center indicates that there is an 80% chance of this year’s Tropical Storm Alberto to develop in the Gulf of Mexico in the next five days, even before the season officially begins. While it is not likely to bring extreme winds and storm surge to the area, it is expected to bring copious rain to an area that has already received up to six times as much rain as usual in the last week, covering most of Georgia except the northwest corner. Another six inches is expected across a wide area of Georgia in the next seven days from the slowly moving storm. While this is not likely to be as wet as the 1994 TS Alberto, the wind and rainfall are still going to cause tremendous problems for us here in Georgia, along the coast and inland across most of the state.
Now is the time to think about what you need to do to get ready for the rain, whether or not it organizes enough to be designated as a named tropical storm. If you have weekend activities planned along the Gulf Coast for this Memorial Day weekend, be prepared for intermittent heavy rains, gusty winds, high waves and rip currents in the water along the coast from New Orleans to the west coast of Florida. If you are inland, prepare for localized flooding which will be worse because the ground is already saturated in many areas. Move equipment and livestock out of low-lying areas. Expect some trees to fall because of the wet soil conditions, even if the winds are not that strong. This may mean blockage of roads or disruptions in power, so check your generators now if you need supplemental electricity for your operations. If water covers the road, do as the National Weather Service recommends and “Turn Around, Don’t Drown.” You won’t be able to tell if the road has been undercut or washed away, and water has a tremendous potential to move cars and trucks even when only a few inches deep. The Extension Disaster Education Network (EDEN) has several useful publications on preparation and recovery at https://eden.lsu.edu/educate/resources.
I have heard from a number of contacts that the rain and cloudy conditions over the past two weeks has caused a lot of problems for producers, leading to splitting blueberries, increased fungal diseases, slow growth of crops, and the inability to get into the field to do side dressing of corn, application of fungicides and other treatments, and planting. Unfortunately, I don’t see a shift in this current pattern, and above average rainfall is likely to continue for the next several weeks, although there will be some drier periods that may allow you to get work done.
For updated information follow @SE_AgClimate or on Facebook at SEAgClimate. An excellent source of updated weather information is the local National Weather Service office, but you can also get information from many commercial vendors and the National Hurricane Center. Do not count on your smartphone weather apps to give you the most current information, since many of them are only updated once or twice a day. Keep monitoring for changing conditions, since above average sea surface temperatures in the Gulf of Mexico could lead to a rapid drop in pressure and increase in winds as the center of the storm gets closer to land, or the storm could move in a different direction under weak steering currents.
If you have comments to share about how the current rainy and cloudy weather is affecting your work and your crops, please feel free to send them to me at email@example.com. I always like to hear how the weather and climate are affecting Georgia agriculture.
Interim Director, Georgia Weather Network
Crop and Soil Sciences, CAES
Post authored by Paul J. Pugliesea and Shimat V. Josephb
aUGA County Extension Agent/Coordinator (Bartow County), Cartersville, GA
bAssistant professor, Department of Entomology, University of Georgia – Griffin Campus.
Granulate ambrosia beetle, Xylosandrus crassiusculus (Mot.) [Previously known as the Asian ambrosia beetle]
Introduction: Granulate ambrosia beetle (Fig. 1) is a serious pest of woody trees and shrubs in Georgia. These tiny beetles were first detected in South Carolina in the 1970’s and have spread across the southeastern US.
Host plants: Woody ornamental nursery plants and fruit trees are commonly affected. In spring or even in late winter (around mid-February), a large number of beetles can emerge and attack tree species, especially when they are young. Some highly susceptible tree species include Styrax, dogwood, redbud, maple, ornamental cherry, Japanese maple, crepe myrtle, pecan, peach, plum, persimmon, golden rain tree, sweet gum, Shumard oak, Chinese elm, magnolia, fig, and azalea.
Biology: The female beetles land on the bark of woody trees. Then, they bore through the soft wood and vascular tissues (xylem vessels and phloem) of the tree. They settle in the heartwood and begin making galleries. Eggs are laid in these galleries. Adults introduce a symbiotic fungi into the galleries as a food source for the developing larvae.
Symptoms: The initial sign of infestation is presence of boring dust pushing out of the bark as “tooth picks” (Fig. 1). Severely infested trees with granulate ambrosia beetle may show symptoms of stunting, delayed leaf emergence in spring, and extensive defoliation.
Monitoring and management: Once adults of granulate ambrosia beetle bore through the bark, there are limited control options to mitigate the problem. Those settled beetles in the heartwood of the tree are less likely to be exposed to insecticides. Also, the beetles do not consume the wood, which further minimizes their pesticide exposure. Pyrethroid insecticides such as bifenthrin or permethrin can be used as preventative sprays to repel invading females. Thus, the insecticide-application timing becomes critically important for management. The insecticide applications can be timed with trap captures or adult activity. The simplest method to determine adult activity in the area is using alcohol and a bolt of wood (Fig. 2). A wood bolt (about 2 to 4-inches in diameter and 2-feet long) can be utilized. Any hardwood species such as maple will work for building traps. A half-inch diameter hole drilled at the center of the bolt, about a foot deep, is filled with alcohol and the opening can be closed using a stopper cork. Ethyl alcohol or grain alcohol with 95-percent alcohol content (190-proof) can be found at most liquor stores. Hang several bolt traps along the woodland border of a nursery at waist height to determine beetle emergence and activity. Sawdust tooth picks (Fig. 2) begin to appear on the bolt when they are infested with adult beetles. Once tooth picks are detected on a bolt trap, daily scouting should occur on nearby trees.
An immediate spray using a pyrethroid insecticide on nursery trees is warranted upon detection of tooth picks on the bolt trap. Be prepared and ready to act quickly as soon as beetle activity is confirmed. If practical, the entire nursery should initially be treated with an area-wide application to repel beetle activity. If individual trees are found to be infested, immediately destroy infested trees and follow up with targeted spray applications in blocks with beetle activity. Generally, pyrethroids are not effective for more than a week as their residues quickly breakdown. Re-application of the insecticide is generally required at weekly intervals until spring green-up is complete in areas where the beetle pressure is moderate to severe.
Healthy trees can withstand a low level of beetle infestation. Timely irrigation and adequate fertilization of trees throughout the growing season will increase a tree’s tolerance to beetle infestation. Closely monitor traps throughout the spring for a second emergence of ambrosia beetles. Ambrosia beetles can have multiple generations throughout the year and are strongly attracted to trees that are drought stressed, injured, or excessively pruned. Pay close attention to irrigation needs during extended summer and fall drought periods to minimize tree stresses. Avoid mechanical wounding of trees with maintenance equipment that could invite ambrosia beetles to attack.
When to deploy monitoring traps: The monitoring traps should be deployed starting the first week of February in Georgia because warmer periods during a mild winter may trigger early beetle emergence and infestation.
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