Root Diseases Of Turf-Grasses In Transitional Zone Of China

The root diseases of turf is that which pathogen infects root , stolon, rhizome, crown and base of shoot. The serious root diseases, occurred in transitional zone of warm-season turf and cool-season turf, had became an important factor restricting the development of turf. The occurrence of root diseases in transitional zone, included 23 counties from 5 provinces (Shanghai, Shandong, Shaanxi, Zhejiang and Henan), were surveyed , and pathogens were identified. Etiological study were conducted for new diseases and important diseases followed Koch's rule. the following main results were obtained.1. The root diseases occurred in transitional zone included take-all disease, brown patch, Pythium blight, Fusarium disease, Curvularia disease, Drechslera disease, Bipolaris disease, Exserohilum disease, Nigrospora disease, Phoma disease, Golf Green gray patch, anthracnose, spring dead spot, Zoysia ring spot and fairy ring. The brown patch occurred widely and seriously, take-all disease occurred locally and dangerously, spring dead spot and anthracnose occurred locally and seriously, Curvularia disease, Bipolaris disease and Fusarium disease occurred widely but not seriously.2. The take-all patch disease was first found on the turf-grasses of Lolium perenne and Festuca arundinacea in Xuhui, Pudong and Jing'an region, Shanghai, which caused by the pathogen of Gaeumannomyces graminis var. graminis. The average incidence and severity were 16.3% and 2.0 respectively. The take-all disease was dangerous, and it was advised to quarantine and eradicate.3. The pathogenicity of Ggg to main turf-grasses was evaluated by Person procedures, The tested pathogen had the high pathogenicity to Cynodon dactylom and Agrostis palastris, which severity was more than 48.7%, higher than 38.7% of rice(CK), and moderate pathogenicity to Zoysia japonica, Lolium perenne, Festuca arundinacea and Poa pratensis, but there were resistant cultivars in Lolium perenne, Festuca arundinacea and Poa pratensis. Further research on the take-all disease should be conducted to obtain a basis for quarantine, monitoring and control in future because Ggg had high pathogenicity to main turf-grasses.4. Pathogenicity of Gaeumannomyces graminis, including Gga, Ggt and Ggm, to 9 turf-grasses ( 48 cultivars ), were evaluated by Person procedures. The results showed that Ggm had the low pathogenicity with the untypical symptoms and low incidence and severity. Ggt and Gga had the high pathogenicity to Cynodon dactylom and Agrostis palastris, as well as several cultivars of Lolium perenne and Poa pratensis, moderate pathogenicity to other tested turf-grasses. Chinese isolates of Ggt should be controlled to prevent their dispersal from wheat field to turf because of its high potential of pathogenicity, Gga had not occurred in China and quarantine should be conducted.5. The brown patch occurred widely in transitional zone, distributed 23 counties of 5 provinces, the average incidence and severity were 5% ~ 80% and 2.0 ~5.0 respectively. The brown patch was not necessary to be quarantined in China because of its widely occurring range.6. 73 isolates of Rhizoctonia were obtained from 97 specimen, 6 species of infected turf-grasses, The nuclei were stained to determine the number in vegetative hyphal cells by DAPI staining nuclear technique. Uninucleate Rhizoctonia(3), binucleate Rhizoctonia(20) and multinucleate Rhizoctonia(50) were distinguished among the tested Rhizoctonia isolates. The uninucleate Rhizoctonia was first recorded in China, and the turf-grasses were its new hosts.7. The pathogenicity of uninucleate Rhizoctonia to main turf-grasses and crops was evaluated. The pathogen could infect all the tested turf-grasses, and had the most strong pathogenicity to Agrostis palastris with the disease index of 60.0, the moderate pathogenicity to Lolium perenne, Zoysia japonica, Festuca arundinacea, Poa pratensis, Cynodon dactylom with the disease index between 35.0 ~ 40.8. It also had pathogenicity to Triticum aestivum, Zea mays, Oryza sativa, Gossypium hirsutum, Raphanus sativus, the pathogenicity to Gossypium herbaceum and Raphanus sativus was high with disease index 58.3 and 55.8, and that was middle to Oryza latifolia, tritici and maydis with disease index 48.3, 48.3 and 44.2. The uninucleate Rhizoctonia, found first in China, had pathogenicity to turf-grasses and crops, which should be researched more in future.8. The binucleate Rhizoctonia and multinucleate Rhizoctonia were identified based on the cyto-morphology of hyphae and the morphology of cultures followed Sneh procedures. All the binucleate Rhizoctonia isolates were Rhizoctonia cerealis(20). Rhizoctonia solani(43),Rhizoctonia oryzae(3)and Rhizoctonia zeae(4)were distinguished among the multinucleate Rhizoctonia. Rhizoctonia solani were the preponderant pathogen which were the multinucleate Rhizoctonia proportion of 86%, and all brown patch isolates proportion of 58.9%. The pathogens of brown patch disease were complex greatly, Rhizoctonia oryzae and Rhizoctonia zeae were first report to be the pathogen of brown patch formally in China. 9. Anastomosis group testing of Rhizoctonia solani from the transition zone turf-grasses were conducted by Parmeter's methods. 4 anastomosis groups, AG-1(AG1-1A and AG1-1B),AG-2(AG2-1, AG2-2IIIB and AG2-2IV), AG-4 and AG-5, were confirmed among the 38 Rhizoctonia solani isolates of turf-grasses. AG-1 and AG-2, Rhizoctonia solani isolates proportion of 32.6% and 39.5% respectively, were the dominant anastomosis group and isolated from all the turf-grasses and provinces. AG-4 was isolated from Zoysia japonica and Poa pratensis, only in Yantai city and Weihai city, Shandong province. The anastomosis group types of brown patch pathogen in China were complex, the anastomosis group reported in foreign country also occurred in China. AG1-1B and AG2-1 is the first reported anastomosis sub-group of Rhizoctonia solani infecting turf-grasses.10. The pathogenicity of uninucleate Rhizoctonia, binucleate Rhizoctonia, Rhizoctonia solani,Rhizoctonia oryzae and Rhizoctonia zeae, to main turf-grasses were tested. All the tested isolates could infest Lolium perenne, Zoysia japonica, Festuca arundinacea, Poa pratensis, Agrostis palastris, Cynodon dactylom, and had the high pathogenicity to Agrostis palastris with above disease index of 57.5. The difference of pathogenicity among all the tested pathogen was slight except that Rhizoctonia solani had higher pathogenicity than others. The pathogenicity of all the pathogens to crops, Triticum aestivum, Zea maydis, Oryza sativa, Gossypium hirsutum, Raphanus sativus, was also tested. The pathogenicity to Gossypium hirsutum and Raphanus sativus was high with disease index of 58.3 and 51.7, Rhizoctonia solani had high pathogenicity to Oryza sativa with disease index of 71.7, All the pathogens of brown patch disease had high pathogenicity to main turf-grasses and crops, therefore the list of pathogen needed to be quarantined should be modified because only one pathogen of Rhizoctonia solani on the quarantine list had not illuminated the fact of brown patch pathogens based on the survey results and pathogenicity results.11. The brown patch pathogens were selected to analyz the ITS sequence according to the identification and anastomosis group. the ITS cluster was consistent with asexual state morphology, and had the different anastomosis group with AG-2 and AG-4. This was the first mensuration of brown patch pathogen ITS in China, and the results were relative with morphology and anastomosis groups.12. The Curvularia pathogen, including Curvularia lunata and Curvularia inaequalis etal., infected the Green of Golf(Agrostis palastris), caused serious symptom which could destroy the landscape of Green, lower the course life, and control and monitoring should be strengthened. 13. The anthracnose occurred seriously in Yangling, Shaanxi province, spring dead spot was the major disease in Shanghai bermudagrass turf. These two diseases were of importance locally, management and monitoring measure should bedone to prevent their dispersal.The occurrence and importance of turf-grass root diseases in transitional zone, were revealed by this project, and two serious diseases, take-all and brown patch, were studied in detail. The results filled a gap of understanding turf root disease in China, and provides the basic information for further in-depth study on turf diseases, as well as the fundamental for quarantine, monitoring and control of root diseases.