Scout early for timely control Spring & early summer turfgrass diseases

by Alfredo Martinez Espinoza, PhD, UGA Department of Plant Pathology

Large patch is caused by the soilborne fungus Rhizoctonia solani AG 2-2 LP. The disease can infect all species of warm-season turfgrasses, including St. Augustinegrass, zoysiagrass, centipede and bermudagrass. The disease is apparent during the spring and fall, when warm-season turfgrasses are entering or exiting their period of winter dormancy. R. solani occurs whenever the temperature of the thatch layer is between 50ºF (10ºC) and 70ºF (21ºC), and continuous moisture is available for at least 48 hours.

Rhizoctonia large patch is the most common and severe disease of warm-season grasses across the state of Georgia. Circular patches of affected turf are easily observed, ranging in diameter from less than 3.3 ft. (1 m) up to 26.4 ft. (8 m). Leaves of recently infected turf, located at the periphery of the patch, may appear bright yellow and/or orange in color. Some patches may be perennial, recurring in the same location and expanding in diameter year after year. R. solani infection of warm-season grasses occurs on the leaf sheaths, where water-soaked, reddish-brown or black lesions are observed. Foliar dieback from the leaf tip towards the base occurs as a direct result of these leaf sheath infections. The centers of the patches develop thin and sunken areas that may be invaded by weeds.

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Establish a turfgrass species best adapted to your geographical area and situation. Make sure that areas are well-drained, as moisture levels in the thatch and soil is an essential aspect of large patch management. Prevent and/or alleviate soil compaction. Implement a sound fertility program according to recommended guidelines for your particular turf species and an updated soil test. Cut grass at the proper mowing height for that species. Emphasize cultural and genetic control on home lawns, as few effective fungicides are available for the public to use for large patch management.

Large patch is apparent during the spring and fall, when warm-season turfgrasses are entering or exiting their period of winter dormancy.

Nematodes injure turfgrass roots by either feeding on, or burrowing through, tissues.

4Apply fungicides in the following classes for commercial turf: carboxamides, benzimidazoles, carbamates, dicarboximides, DMI fungicides, di-nitro anilines, nitriles, polyoxins, and Qo inhibitors.

For more information on large patch:

Nematodes are small round worms that are common in soils and aquatic environments.

About 15% of described nematodes are plant parasites. Most plant pathogenic nematodes are 0.5 to 4 mm in length.

Plant parasitic nematodes (PPNs) feed through a retractable hollow or grooved spear (stylet). PPNs can be grouped by their mode of feeding. Those that remain outside of the plant are called ectoparasites; endoparasites enter into the plant tissue. Some endoparasites remain in one place and feed and others migrate through the tissues.

PPNs can become a significant factor affecting the health, quality, production, and maintenance of warm- and cool-season turfgrass on landscapes, golf courses, sports fields and in sod production. Major PPNs frequently found associated with turfgrass in Georgia include lance (Hoplolaimus spp.), ring (Mesocriconema spp.), root-knot (Meloidogyne spp.), spiral (Helicotylenchus spp.) sting (Belonolaimus longicaudatus), stubby root (Trichodorus spp.) and stunt (Tylenchorhynchs spp.) nematodes.

Nematodes injure turfgrass roots by either feeding on, or burrowing through, tissues. Depending on the host and the nematode involved, symptoms on roots include inhibition of root elongation, swollen tips, galls, lesions, and shortened stubby roots. In most cases root symptoms are not obvious. Patchy areas of wilting, thinning and decline occur where nematode populations are excessively high. These above-ground symptoms are of little value in diagnosing nematode problems in turf. An accurate assessment of the pathogenic potential of nematodes can only be determined by a nematode assay.

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Have a soil test done, send root zone soil sample to a Nematology lab to quantify and identify the nematode species. Negative nematode effects will only occur if soil population numbers exceed estimated damage thresholds levels. Fertilize if necessary and water appropriately to keep grass as vigorous as possible. Nutrient deficiencies and soil compaction can inhibit root development and increase turf sensitivity to nematode damage. There are several nematocides available including Divanem (abamectin),

All photos courtesy of Alfredo Martinez

azaguard (azadirachtin), Nortic (Bacillus firmus), Nimitz (fluensulfone), Indemnify (fluopyram), MultiGuard protect (furfural),

Econem (Pasteuria usagae), Neo-Tec (sesame oil). Check product labels as some of these nematicides restrict on what type of site they can be used. For a complete list of nematicides consult the 2019 Georgia Pest Management Handbook:

Centipede is subject to a condition called centipedegrass decline: failure to green-up in the spring or successful green-up followed by decline and death in late spring and summer. For information on centipede decline visit

Dollar spot (Clarereedia Spp., formerly Sclerotinia homoeocarpa) is ubiquitous in all warm-season Dollar spot starts early in the spring and can linger throughout the summer.

grasses in Georgia. The disease starts early in the spring and can linger throughout the summer. Dollar spot is particularly troublesome in bermudagrass and zoysiagrass. Start scouting now for the disease to implement control measures in a timely manner. Information on dollar spot identification and control can be found at http://extension.uga.edu/