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.
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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.
Fall Turfgrass Disease Prevention and Control
by Alfredo Martinez
Rhizoctonia large patch is the most common and severe disease of warm season grasses (bermudagrass, centipedegrass, seashore paspalum, St. Augustinegrass, and zoysiagrass) across the state of Georgia. Due to spring and fall disease-promoting environmental conditions across Georgia coinciding with grasses leaving and/or entering dormancy, large patch can appear in warm season grasses in various grass-growing settings, including home lawns, landscapes, sports fields, golf courses, and sod farms. Symptoms of this lawn disease include irregularly-shaped weak or dead patches that are from 2 feet to up to 10 feet in diameter. Inside the patch, you can easily see brown sunken areas. On the edge of the patch, a bright yellow to orange halo is frequently associated with recently affected leaves and crowns. The fungus attacks the leaf sheaths near the thatch layer of the turfgrass.
Large patch disease is favored by:
- Thick thatch.
- Excess soil moisture and poor drainage.
- Too much shade, which stresses turfgrass and increases moisture on turfgrass leaves and soil.
- Early spring and late fall Nitrogen fertilization.
If large patch was diagnosed earlier, fall is the time to control it. There is a myriad of fungicides that can help to control the disease. Fungicides in the following classes are labeled for large patch control: carboxamides, benzimidazoles, carbamates, dicarboximides, DMI fungicides, di-nitro anilines, control. For a complete and updated list of fungicides available for commercial control of large patch, visit http://extension.uga.edu/publications/detail.cfm?number=SB28 or http://www.commodities.caes.uga.edu/turfgrass/georgiaturf/Publicat/1640_ Recommendations.html. Preventative or curatives (depending on the particular situation) rates of fungicides in late September or early October and repeating the application 28 days later are effective for control of large patch during fall. Fall applications may make treating in the spring unnecessary. Always follow label instructions, recommendations, restrictions and proper handling.
Cultural practices are very important in control. Without improving cultural practices, you may not achieve long term control.
- Use low to moderate amounts of nitrogen, moderate amounts of phosphorous and moderate to high amounts of potash. Avoid applying nitrogen when the disease is active.
- Avoid applying N fertilizer before May in Georgia. Early nitrogen applications (March-April) can encourage large patch.
- Water timely and deeply (after midnight and before 10 AM). Avoid frequent light irrigation. Allow time during the day for the turf to dry before watering again.
- Prune, thin or remove shrub and tree barriers that contribute to shade and poor air circulation. These can contribute to disease.
- Reduce thatch if it is more than 1 inch thick.
- Increase the height of cut. Reduced mowing heights result in a more dense turf stand, which may create a more favorable environment for large patch development
- Improve the soil drainage of the turf.
- Control traffic patterns to prevent severe compaction, and core aerate to improve soil drainage and increase air circulation around the shoots and root
For more information on large patch visit https://secure.caes.uga.edu/extension/publications/files/pdf/C%201088_2.PDF
Spring Dead Spot of Bermudagrass
Fall cultural practices and fungicide applications are key for Spring Dead Spot management. The disease is caused by fungi in the genus Ophiosphaerella (O. korrae, O. herpotricha and O. narmari). These fungi infect roots in the fall predisposing the turf to winter kill. As indicated by its name, initial symptoms of spring dead spot are noticeable in the spring, when turf resumes growth from its normal winter dormancy. As the turf ‘greens-up,’ circular patches of turf appear to remain dormant, roots, rhizomes and stolons are sparse and dark-colored (necrotic). No growth is observed within the patches. Recovery from the disease is very slow. The turf in affected patches is often dead; therefore, recovery occurs by spread of stolons inward into the patch. The causal agents of SDS are most active during cool and moist conditions in autumn and spring. Appearance of symptoms is correlated to freezing temperatures and periods of pathogen activity. Additionally, grass mortality can occur quickly after entering dormancy or may increase gradually during the course of the winter. Spring dead spot is typically more damaging on intensively managed turfgrass swards (such as bermudagrass greens) compared to low maintenance areas.
- Practices that increase the cold hardiness of bermudagrass generally reduce the incidence of spring dead spot. Severity of the disease is increased by late-season applications of nitrogen during the previous fall.
- Management strategies that increase bermudagrass cold tolerance such as applications of potassium in the fall prior to dormancy are thought to aid in the management of the disease. However, researchers have found that fall applications of potassium at high rates actually increased spring dead spot incidence. Therefore, application of excessive amounts of potassium or other nutrients, beyond what is required for optimal bermudagrass growth, is not recommended.
- Excessive thatch favors the development of the disease. Therefore, thatch management is important for disease control,
- Implement regular dethatching and aerification activities.
- There are several fungicide labeled for spring dead spot control.
- Timing, selection and application of fungicides are important for preventative management of SDS. Fungicide application in the fall when soil temperatures are between 60° and 80° F provides the best control of SDS
- A complete list of fungicides, formulations and product updates for SDS can be found in the annual Georgia Pest Management Handbook and the Turfgrass Pest Control Recommendations for Professionals (http://www.georgiaturf.com). Some fungicide options are exclusively for golf course settings. Always check fungicide labels for specific instructions, restrictions, special rates, recommendations, follow-up applications and proper handling.
For more information on SDS visit https://secure.caes.uga.edu/extension/publications/files/pdf/C%201012_3.PDF
Early detection of bermudagrass leaf spot
Severe leaf and crown rot, caused by Bipolaris ssp. can occur in bermudagrass lawns, sport fields, or golf fairways. Initial symptoms of this disease include brown to tan lesions on leaves. The lesions usually develop in late September or early October. Older leaves are most seriously affected. Under wet, overcast conditions, the fungus will begin to attack leaf sheaths, stolons and roots resulting in a dramatic loss of turf. Shade, poor drainage, reduced air circulation; high nitrogen fertility and low potassium levels favor the disease. To achieve acceptable control of leaf and crown rot, early detection (during the leaf spot stage) is a crucial.
Dollar spot is still active in the fall/early winter
Dollar spot is most prevalent during spring and fall with infections developing rapidly at temperatures between 60 and 75 degrees Fahrenheit combined with long periods of leaf wetness from dew, rain, or irrigation.
- Excessive moisture on turfgrass foliage will promote dollar spot epidemics. Irrigating in the late afternoon or evening should be avoided, as this prolongs periods of leaf wetness.
- If feasible, prune or remove trees and shrubs to promote air movement and accelerate drying of the turfgrass canopy
- A variety of fungicides are available to professional turfgrass managers for dollar spot control including fungicides containing benzimidazoles, demethylation inhibitors
(DMI), carboximides, dicarboximides, dithiocarbamates, nitriles and dinitro-aniline. Several biological fungicides are now labeled for dollar spot control.
- For a complete and updated list of fungicides available for dollar spot, visit http://extension.uga.edu/publications/detail.cfm?number=SB28 or http://www.commodities.caes.uga.edu/turfgrass/georgiaturf/Publicat/1640_Recommendations.htm.
Additional information on dollar spot visit https://secure.caes.uga.edu/extension/publications/files/pdf/C%201091_2.PDF
Slime Mold on Turfgrasses
Has your lawn been slimed? Fear not, the grayish-black sooty substance on your turfgrass is a harmless soil protozoa that has temporarily migrated onto blades and stems to produce and disperse spores. Diagnosis: Slime Mold, Physarum and Fuligo sp./spp. The occurrence is prompted by spells of humid, rainy weather during spring and early summer and is typically short-lived (1-2 weeks). Aside from temporarily hindering photosynthesis, slime molds do not parasitize or damage the turfgrass. Slime mold can be ignored, mowed, raked, or washed off with a pressurized stream of water.
Related Articles: what-is-this-unusual-growth-on-lawns
If you missed the window of opportunity to manage burweed in your lawn in late winter/early spring, then you may be feeling it, literally! The seed burs are now mature and a barefoot stroll across the lawn may inflict you with some painful hitchhikers. At this point, applying a broadleaf herbicide product may kill the weed, but will not eliminate the existing burs that have formed, so mark your calendars for burweed scouting and control next February. If an immediate solution is needed, locate individual plants and physically remove them. Burweed tends to colonize compacted bare areas. For large areas of infestation it may be necessary to scalp and bag the clippings with a mower to remove the burs, followed by turfgrass renovation or establishment on those areas (assuming that you have a warm-season turfgrass species such as bermudagrass, it would not be advisable to scalp a Tall Fescue lawn in May). For more information on scouting for lawn burweed, refer to the previous post “Winter Scouting for Lawn Burweed.”
Related articles: winter-scouting-for-burweed-soliva-pterosperma
Now is the time to aerify warm-season turfgrasses. Last year, the dry conditions persisting from August through December depleted carbohydrate reserves in warm-season turfgrasses. A delay in turfgrass green-up was common this spring and warm-season turfgrasses are poised to replenish carbohydrate reserves and restore root systems. “If there is a year to seriously consider core aerification, this is it,” says Dr. Clint Waltz, a Cooperative Extension turfgrass specialist with the University of Georgia College of Agricultural and Environmental Sciences. Core aerification relieves compaction, improves air exchange and water infiltration, and stimulates deeper root growth. Hollow-tine aerification is the preferred method, removing soil cores to a depth of 3-4 inches, and having longer-lasting benefits. A light fertilizer application in concert with aerification can be beneficial, but heavy nitrogen applications should be avoided to allow for the replenishment of carbohydrate reserves (over-stimulating top growth depletes carbohydrates reserves).
To make sure soil pH, phosphorus and potassium levels are within recommended ranges for optimum growth, take a soil sample to your local University of Georgia Cooperative Extension office.
Read the full article on Core Aerification and find lawn care calendars for different turfgrass species at www.GeorgiaTurf.com .
Related Articles and Publications:
Turfgrass Fertility: Soil Texture, Organic Matter, Aeration, and pH (C 1058-1)
The Georgia Urban Ag Council, a professional organization representing the Georgia landscape industry, is working to find solutions to the issue of equipment theft at worksites, offices, and storage facilities. This week, an incident in Lilburn ended with gun shots fired at landscape employees who discovered perpetrators stealing equipment from the company box truck. The Georgia Urban Ag Council has established a Twitter account titled “GA Landscape Thefts” and is compiling information, articles, and reports from owners and residents experiencing equipment theft. Armed with this data, the UAC hopes to assist law enforcement agencies, equipment manufacturers, and suppliers in determining a course of action to reduce losses.
Here are some general equipment theft prevention strategies to consider:
- Train employees on company procedures to deter equipment theft. In addition, discuss what to do in the event of a theft or robbery.
- Take Inventory: Establish a routine of equipment inventory. Keep documentation and photo records of serial numbers, makes, and models of equipment.
- Parking strategy: Be strategic about where you park your vehicle on each jobsite or lunch destination. Park in well lighted locations visible to the work crew and avoid leaving equipment unattended in back lots or hidden areas that are conducive to theft. Position trailers so they aren’t easily accessed or swapped to another vehicle.
- Deterrents: Lock vehicles, trailers, trailer tongues, and secure equipment when unattended. Don’t leave keys in trucks or commercial mowers.
- Tracking Devices: Install tracking devices on large equipment.
- Be Alert: Pay attention to suspicious activity.
- Insurance: Review your policy and ask your insurance provider about theft prevention.
Related Articles & News:
Dr. Clint Waltz, Extension Turfgrass Specialist with the University of Georgia, reports that hot temperatures and low rainfall in the fall of 2016 likely sent warm-season turfgrasses into winter dormancy with depleted carbohydrate reserves. During “normal” circumstances warm-season turfgrasses accumulate and store carbohydrates from late summer through early fall. Last year, non-irrigated turfgrasses likely suffered drought-induced dormancy and transitioned to winter a weakened condition. With insufficient energy accumulated in root systems, a thin canopy and a two- to four-week delay in the green-up of warm-season grasses might be common this spring.
What can be done to improve the green-up and growth of warm-season turfgrasses this spring?
1) AERIFICATION – Core aerification in late April to mid-May. This will improve air exchange and water infiltration to stimulate root and shoot growth. Performing hollow-tine aerification that removes 1/2 inch diameter soil cores to a 3 or 4 inch depth is the recommended approach.
2) TIMING OF FERTILIZER – Withhold the application of nitrogen fertilizer until soil temperatures at the 4-inch depth are consistently 65 degrees and rising. Visit www.Georgiaturf.com to find lawn calendars that include fertility recommendations for each species. Soil temperature data from the Georgia Automated Environmental Monitoring System can be found at www.Georgiaweather.net.
3) SOIL TESTING – Collect a soil sample and submit for testing to ensure that soil Ph, phosphorous, and potassium levels are within the recommended ranges for optimum growth. Contact your local UGA Extension Agent about submitting a soils sample to the UGA Agriculture and Environmental Services Laboratory or call 1-800-ASK-UGA1.
Restoring carbohydrate reserves this spring is an important step in preparing turfgrasses for a healthy growing season. Read the full article by Dr. Clint Waltz at www.Georgiaturf.com.
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