RESEARCH REPORT

Ecology, pathogenicity and management of of the samples was attributed to Bipolaris species. from with blight symptoms, was pathogenic at Bipolaris and fungal species associated Curvularia blight was the most prevalent reported 30° C in zoysia, bentgrass, and bermudagrass. with decline of ultradwarf bermudagrasses in disease from late spring to late fall. Turfgrass canopies in Florida consistently reach these Florida. The was isolated off of the major- temperatures used for the previous pathogenicity Ultradwarf Decline

By Dr. Lawrence E. Datnoff, Dr. Carol Stiles, Dr. ity of turfgrass samples brought into the labs (Stowell, studies from late spring through the fall. John Cisar and Matthew O. Brecht, Ph.D. personal comm.; Unruh and Davis, 2001). While While Bipolaris species are more often Candidate, Principal Investigators Curvularia species were frequently recovered from attributed to causing a disease in turfgrass (Couch both healthy and diseased ultradwarf bermudagrass 1995), little information is available about the role Rationale/description of problem: tissue, it is often unclear whether the fungus is the pri- these fungi play in affecting ultradwarf bermuda- mary cause of the turfgrass symptoms or a saprophyt- grasses (Pratt, 2001). In fact, very little is known In the Southeast, an increasing number of ic secondary organism (Stowell, personal comm.). An about the pathogenicity, etiology, and ecology of putting greens consist of the new ultradwarf accurate diagnosis is important to the superintendent Bipolaris and Curvularia species and no disease research has been conducted on the ultradwarf bermudagrasses. Basic information on the biology and ability to cause disease by Bipolaris and Curvularia species in the ultradwarf cultivars is critical for devel- oping accurate and rapid diagnostic procedures and for creating optimum, long-term integrated disease- management strategies that the superintendents can use to please their membership.

Benefits of research to golf course superintend- Figure 3. Incidence of selected fungi by season. Figure 4. Incidence of selected fungi by location ents: Fungal abbreviations are as follows: (NE-northeast, C-central, S-south, NW-north- This research will determine whether or F=Fusarium, Cl= Curvularia lunata, west) in Florida. Fungal abbreviations are as fol- not Bipolaris and Curvularia species are directly H=Hansfordia, Bc=Bipolaris cynodontis, lows: F=Fusarium, Cl= Curvularia lunata, responsible for the disease problems in putting greens A=Alternaria, Ac=Acremonium, and C=Codinaea, Bc=Bipolaris cynodontis, comprised of ultradwarf bermudagrasses in Florida. Rs=Ramicloridium subulatum. Bars with the Rp=Robillarda phragmites, E=Epicocum, same letter do not differ significantly at P≤0.05 Cs=Curvularia geniculatus, Ggg=. By understanding which fungi are pathogenic, diag- as determined by the Fisher’s Protected LSD. Gaeumannomyces graminis var. graminis, and nostic procedures can be developed to more accurate- H=Hansfordia. Bars with the same letter do not ly identify the true cause of disease, and allow super- bermudagrass ( X C. differ significantly at P≤0.05 as determined by intendents to correctly manage the situation. the Fisher’s Protected LSD. transvaalensis) cultivars, including Champion, Integrated disease management strategies that includ- Floradwarf, and TifEagle. These grasses rival tradi- since management of certain diseases by fungicides ed cultural (such as mowing heights) and chemical tional creeping bentgrass ( palustris) greens and cultural methods are often specific for that type approaches can then be developed for superintend- in part because of their higher shoot densities, faster of fungus. ents, giving them more options for prevention and ball roll and tolerance to lower mowing heights Although Curvularia species are fre- control of the disease problem. (Hanna, 1998). quently obtained from ultradwarf putting green sam- Recently in the Gulf Coast region ples in Florida, they are not routinely diagnosed as Objective 1: Determine the influence of mowing (Alabama, Florida, Louisiana, and Mississippi), more pathogens by university diagnostic laboratories. One heights and fungicides on the decline of ultradwarf than 70 golf courses in 2000 and 130 golf courses in reason for this is the ongoing debate about the patho- bermudagrass. 2001 reported significant disease problems in their genicity of Curvularia species (Kim et al., 2000). ultradwarf bermudagrass putting greens (Unruh and Brown et al. (1972) demonstrated that various (Editor’s note: The report on objective one can be Davis, 2001). Diagnostic labs, which received turf- Curvularia species could cause disease in cultivars of found in the March/April 2005 Issue of the Florida grass from the diseased greens, attributed the damage Kentucky bluegrass, creeping red fescue, and bent- Turf Digest. Dr. Datnoff was gracious enough to let to spring dead spot (Ophiosphaerella spp.) and grass from 24 to 35° C. In Korea, Kim et al. (2000) us publish his update report on the other two objec- Curvularia blight (Curvularia spp.). Damage in some recently showed that Curvularia inaequalis, isolated tives of the overall project as a timely follow up.)

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RESEARCH REPORT

Objective 2: Determine the occurrence of Isolates of Bipolaris and Curvularia Bipolaris and Curvularia on ultradwarf bermuda- species obtained from the statewide survey will be grass greens in Florida golf courses. used to test their ability to cause both foliar and A statewide systematic study was root disease in Champion, Floradwarf, and undertaken to determine the true extent of Tifeagle. These tests are currently under way. Bipolaris and Curvularia and other fungi associat- ed with disease problems on golf courses with Literature Cited: ultradwarf bermudagrass greens (TifEagle, Bell, A.A. 1967. Fungi associated with root and Champion and Floradwarf) in Florida. Every crown rots of Zoysia japonica. Plant Disease other month samples were collected from eight Reporter 51:11-14. golf course greens located in four geographical Brown, G.E., Cole, H., Jr., and Nelson, R.R. regions of Florida, USA (northeast, northwest, 1972. Pathogenicity of Curvularia sp. to turf- central, southeast), with each region having a grass. Plant Disease Reporter 56(1):59-63. Floradwarf and TifEagle cultivar. This research Cisar, J. and Snyder, G. 2002. Evaluation of actually began in 2003 and is ongoing in 2004. ultradwarf bermudagrass cultural management The data shown herein are from 2003 and a por- practices. USGA Annual Report. 14 pgs. tion of 2004. Couch, H.B., 1995. Diseases of turfgrasses. Twenty different species of fungi Kreiger Publishing Company, Malabar, Florida. and one actinomycete were recovered from the 421pp. two ultradwarf cultivars, including Alternaria Couch, H.B. and Smith B.D. 1987. Relationship sp., Acremonium sp., Biplaris cynodontis, of suscpect nutrition, air temperature, and dura- Bipolaris hawaiiensis, Codinaea sp., tion of leaf wetness to the development of Choanephora sp., Curvularia lunata, Curvularia Helminthosporium leaf spot of creeping bent- geniculatus, Cylindrocarpon sp., Epicoccum grass. Phytopathology. 77(12):1733. (Abstract). sp., Fusarium spp., Gaeumannomyces graminis Hanna, W. 1998. The future of bermudagrass. var. graminis, Hansfordia sp., Leptosphaerulina Golf Course Management. 66(9):49-52. trifolii, Myrothecium leucotrichum, Pestalotia Kemerait, R.C. 2000. A characterization of soil- sp., Penicillium sp., Pythium sp., Robillarda borne fungi associated with peanut (Arachis phragmites, Ramicloridium subulatum, hypogaea L.). Ph.D. Dissertation. University of Rhizoctonia zeae and a Streptomyces species. Florida 338 pp. The incidence of Fusarium sp., Curvularia luna- Kim, J.C., Choi, G.J., Kim, H.J., and Cho, K.Y. ta, Hansfordia sp., Bipolaris cynodontis, 2000. Pathogenicity and pyrenocine production Alternaria sp., Acremonium sp., and of Curvularia inaequalis isolated from zoysia- Ramicloridium subulatum was significantly dif- grass. Plant Disease 85:684-688. ferent depending on the season (P<0.05) Martin, B., Camberato, J., Chunhua, L. and (Figure 3.). Fusarium and Alternaria species Turner, A. 2001. Spring-applied fungicides were recovered significantly (P<0.05) more increase turf quality. Carolinas Green, often on leaves during the winter and spring March/April: 21-23. months than on other plant parts and times of Muchovej, J.J., and Couch, H.B. 1987. the year (data not shown). Acremonium sp. Colonization of bentgrass turf by Curvularia were recovered significantly (P<0.05) more lunata after leaf clipping and heat stress. Plant often on leaves during the spring than on other Disease 71:873-875. plant parts and times of the year (data not Pratt, R.G. 2001 Occurance and virulence of shown). Bipolaris hawaiiensis on bermudagrass The incidence of Biplaris cynodontis, (Cynodon dactylon) on poultry waste applica- Codinaea sp., Curvularia lunata, Curvularia genic- tion sites in Mississippi. Plant Disease 85:1206. ulatus, Epicoccum sp., Fusarium sp., Sivanesan, A. 1987. Graminicolous species of Gaeumannomyces graminis var. graminis, Bipolaris, Curvularia, Drechslera, Exserohilum Hansfordia sp., and Robillarda phragmites was and their teleomorphs. Mycological Papers No. influenced significantly by the location of the turf- 158. grass in the state of Florida (P<0.05) (Figure 4). Smiley, R.W., Dernoeden, P.H., and Clarke, B.B. 1992. Compendia of turfgrass diseases. Objective 3: Ascertain which isolates of Bipolaris APS Press. St. Paul, MN. 106pp. and Curvularia obtained from the statewide survey Unruh, J.B. and Davis, S. 2001. Diseases and are pathogenic and determine disease develop- heat besiege ultradwarf bermudagrasses. ment. Golf Course Management, April 2001, p. 49-54.

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