Landscape Alerts & Updates | February 2019

February 24, 2019February 15, 2019 by Greg Huber

Diseases and Problems to Watch for in Winter and Early Spring

Guest Post by Alfredo Martinez

Microdochium Patch in Golf Courses. When night temps dip below 50°F, Microdochium Patch (Fusarium Patch, pink snow mold) can be severe on new bentgrass and semi-dormant bermudagrass greens, and on greens overseeeded with Poa trivialis. Patches begin as small reddish-brown spots that can grow and coalesce into large blighted areas. White to pink mycelium (sometimes mistaken for Pythium or dollar spot) may appear during extended periods of rain and overcast weather. Cultural controls are the same as those listed above for Yellow Patch. Effective fungicides include products that contain azoxystrobin, fluoxastrobin, iprodione, metconazole, propiconazole, pyraclostrobin, thiophanate-methyl, triadimefon, trifloxystrobin, triticonazole or vinclozolin.

Slime Mold/Sooty Mold;Blackening observed in fully dormant zoysia and or bermudagrass after few rain events? We have received samples exhibiting olive green, gray to black molding affecting dormant tissue This condition is known as slime mold and /or “sooty mold” in other crops. The growth is superficial in nature. While the symptoms are worrisome, the condition does not affect turf further. Sooty mold is the result of secondary, saprophytic fungi and not considered a true disease. Sooty mold develops on dormant, senescing and/or damaged turf when prolonged wet, humid weather occurs. This symptomatology is probably going to go away as sunny, breeze weather resumes. This blackening should mow off rather quickly.

Yellow Patch (Rhizoctonia cerealis).Sporadic infections of R. cerealis(yellow patch) have been observed in ryegrass over-seeded bermudagrass turf swards and sport fields. The disease is rare in the state, but it thrives in extended periods of wet, cloudy weather. It is a cool-temperature disease (50 to 65°F). Disease development is significantly suppressed at temperatures lower than 45°F and greater than 75°F. Avoid excessive nitrogen fertilization in the fall or when the disease is present. Thatch management is essential for disease control. Maintain thatch at less than 0.5 inch. There are several fungicides that can be used to control the disease, however in the state, yellow patch usually does not warrant a fungicide application.

Dollar Spot Can Start Early: The dollar spot fungus (Sclerotinia homoeocarpanow named Clarireediasp) can produce infections on warm season grass as soon as they start to green up. Additionally, dollar spot can continue to infect cool season grasses anytime temps are above 50°F but it is fully active between 60°F and 70°F. Due to low temperatures, recovery of turf from dollar spot symptoms in late winter or early spring may take weeks rather than days. Therefore, preventive control of dollar spot is important at this time of the year. Monitoring fertility is an important first step to controlling dollar spot. Excessive moisture on turfgrass foliage will promote dollar spot epidemics. Excessive thatch layers and compacted soil stresses the plants and slows turfgrass growth and recovery from disease.

Chemical control for practitioners: 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

Alfredo Martinez is a University of Georgia Professor and Extension Plant Pathologist in the areas of turfgrass, small grains, and non-legume forages at the Griffin campus.

Landscape Alerts and Updates – MAY 2017

June 6, 2017May 26, 2017 by Greg Huber

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

Lawn Burweed

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.”

Turf Aerification

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 .

A Rough End to the Season for Warm-season Turfgrasses

October 31, 2016October 28, 2016 by Greg Huber

The lack of rainfall in the second half of the growing season has hindered the production and storage of energy that normally takes place in warm-season turfgrasses from late summer through fall. In effect, warm-season turfgrasses could enter winter dormancy with depleted carbohydrate reserves. Dr. Clint Waltz, Extension Turfgrass Specialist with the University of Georgia, is concerned that winter hardiness and spring green-up issues could result from a rough end to the growing season. The weather over the next few weeks will decide how warm-season turfgrasses cross the finish line into dormancy.

“The limiting factor is water,” said Waltz. The biological activity that is necessary to gather and store carbohydrates requires water and we need some rain. With soil temperatures at the 4″ depth holding in the 60’s for October and the forecast through the end of the month calling for high temperatures near 80 degrees for much of the state, there may be some opportunity for growth where irrigation is available. However, gains will be marginal as the day length, temperatures, and radiant heat levels continue to drop. Applying 1/2″ inch of irrigation per week may be sufficient to help mitigate spring green-up issues and prevent crown desiccation if dry weather continues. Fertilizer is NOT recommended for warm-season grasses at this point in the season, especially nitrogen. Applications of potassium are generally recommended to promote winter hardiness, but without adequate water, the benefits of these applications may not be fully realized.

What can turf managers do to prepare? Irrigate if you can, do not fertilize, minimize mowing and wear damage, and avoid practices such as aeration that would induce additional plant stress as the turfgrass enters dormancy. When using irrigation systems, be sure to follow the parameters of the Georgia Water Stewardship Act of 2010 and stay informed on the latest drought information at www.georgiawatersmart.com. For more information on landscape watering visit www.Georgiaturf.com and download the publication “Best Management Practices for Landscape Water Conservation.” Most importantly, contact your local UGA County Extension Agent at http://extension.uga.edu/about/county/index.cfm or call 1-800-ASK-UGA1