INVESTIGATOR: Hoy, J. W.
PLANT PATHOLOGY & CROP PHYSIOL
LOUISIANA STATE UNIVERSITY
BATON ROUGE, LOUISIANA 70893
BIOLOGY AND MANAGEMENT OF SUGARCANE DISEASES
CLASSIFICATION HEADINGS: R201 . Plant Genome, Genetics, and Genetic Mechanisms; S2020 . Sugar cane; F1160 . Pathology; R202 . Plant Genetic Resources; R212 . Pathogens and Nematodes Affecting Plants
NON-TECHNICAL SUMMARY: Diseases are a significant constraint to productivity and profitability of the Louisiana sugarcane industry. This project will increase understanding of the biology of sugarcane diseases and develop improved, cost-effective management practices.
OBJECTIVES: 1. To evaluate resistance to diseases as part of the sugarcane variety development program. 2. To gain an understanding of the molecular basis of resistance to leaf scald and investigate molecular markers for resistance. 3. To evaluate the impact of common rust and develop appropriate management practices. 4. To evaluate the impact of yellow leaf and develop appropriate management practices. 5. To minimize the impact of ratoon stunting disease through healthy seedcane programs. 6. To provide support for production of certified seedcane for sugarcane farmers. 7. To study changes in the soil microbial community resulting from sugarcane monoculture. 8. To increase understanding of the biology of sugarcane diseases and improve management practices.
APPROACH: A blend of applied and basic research utilizing laboratory, greenhouse, and field experimentation will address the diseases affecting sugarcane in Louisiana. Conventional selection for disease resistance will require field and greenhouse inoculated experiments. Efforts will be initiated to evaluate the molecular basis of resistance to leaf scald and develop molecular markers for resistance. The effects of rust and yellow leaf on yield will be evaluated in field experiments. Fungicides will be evaluated for rust control. Support will be provided for a certified, healthy seedcane program to control systemic diseases, including yellow leaf, ratoon stunting disease, leaf scald, mosaic, and smut. DNA-based comparisons will be conducted on microbial communities in soils with and without a recent history of sugarcane cultivation.
KEYWORDS: plant pathology; sugarcane; disease management; plant disease resistance; epidemiology; plant ecology; molecular biology; crop losses; plant biology; gene expression; plant genetics; nature of disease resistance; crop varieties; certification; disease free organisms; leaf scald (sugarcane); genetic markers; rust (sugarcane); fungus diseases (plants); soil microbiology
PROGRESS: 2007/01 TO 2007/12
OUTPUTS: Fungicide treatments effective in reducing severity of sugarcane brown rust, caused by Puccinia melanocephala, and increasing yield were identified in field experiments. The impact of infection by Sugarcane yellow leaf virus, the causal agent for yellow leaf, on yield was determined in three varieties. The impact of smut, caused by Ustilago scitaminea, was determined in one variety. Differences were detected among six commercial and two near release varieties in the ability to tolerate billet planting. Sugarcane clones with resistance to smut and leaf scald, caused by Xanthomonas albilineans, were identified in the variety selection program. Two clones were delivered to one commercial seedcane company and nine clones were delivered to a second seedcane company from a local quarantine to provide healthy plant material to establish plants that will be the source of meristems for micropropagation of seedcane for sugarcane farmers. The Sugarcane Disease Detection Lab provided monitoring for ratoon stunting disease, caused by Leifsonia xyli subsp. xyli, and yellow leaf for the variety selection and release programs, commercial seedcane companies, and sugarcane farmers. A proteomic analysis of the resistance reaction of sugarcane to leaf scald was initiated, and the inheritance of resistance was evalutated in seedling populations. PARTICIPANTS: Cooperating scientists included: Dr. Mike Grisham and Dr. Anna Hale, USDA-ARS-SRRC Sugarcane Research Unit, Houma, LA; Dr, Kenneth Gravois, LSU Agricultural Center Sugar Research Station, St. Gabriel, LA; Dr. Collins Kimbeng, School of Plant, Environmental and Soil Sciences, LSU Agricultural Center, Baton Rouge, LA; Dr. Z.-Y. Chen, Department of Plant Pathology and Crop Physiology, LSU Agricultural Center, Baton Rouge, LA; Freddy Garces, graduate student, Department of Plant Pathology and Crop Physiology, LSU Agricultural Center, Baton Rouge, LA. A plant pathology summer internship was provided to Ms. Lauren VanZandt. TARGET AUDIENCES: Target audiences for this project included sugarcane producers and agricultural research professionals.
IMPACT: 2007/01 TO 2007/12
The 2007 results of fungicide efficacy testing for brown rust control in sugarcane considered together with results from 2006 indicate that strobilurin fungicides are more effective than triazole fungicides. Pyraclostrobin alone and in combination with different triazole fungicides has provided the most effective rust control. The efficacy results were used to obtain funding from the USDA IR-4 program to support residue testing for pyraclostrobin and metconazole during 2008. The reliance on varietal resistance for brown rust control has provided inconsistent disease control resulting in occasional losses in excess of 20%. It appears that fungicides can provide an alternative control measure for brown rust when varietal resistance is overcome by the pathogen. The determination of the amount of yield loss caused by yellow leaf and smut will assist farmers in variety planting decisions and should encourage utilization of a healthy seedcane program. Likewise, information on the ability of varieties to tolerate planting as billets will assist farmers in variety planting decisions. It is essential that varietal resistance to diseases be determined as part of the variety selection program. Resistant clones will be used as parents in the recurrent selection sugarcane breeding program. A new variety, HoCP 00-950, with resistance to the major diseases of sugarcane was released during 2007. A proteomic analysis of sugarcane resistance to leaf scald will improve our understanding of resistance and could lead to the development of molecular markers to improve resistance selection for this erratic disease. The local quarantine and disease testing performed by the Sugarcane Disease Detection Lab are important components of the healthy seedcane program that is essential for a vegetatively propagated crop such as sugarcane.
PUBLICATIONS (not previously reported): 2007/01 TO 2007/12
1. Hoy, J. 2007. New option for brown rust control? Sugar J. 69(10):6-7.
2. Hoy, J. 2007. Need for healthy seedcane and disease testing. Sugar Bull. 85(11):22-23.
3. Hoy, J. W., Arceneaux, A. E., and Savario, C. F. 2007. Billet planting research. Page 184 in: Sugarcane Research Annual Progress Report, 2006. La. State Univ. Agric. Exp. Sta. publ.
4. Hoy, J. W., Grelen, L. B., Savario, C. F. and Paccamonti, J. Q. 2007. Pathology Research. Pages 148-160 in: Sugarcane Research Annual Progress Report, 2006. La. State Univ. Agric. Exp. Sta. publ.
PROGRESS: 2006/01/01 TO 2006/12/31
Sugarcane clones were evaluated for resistance to diseases, including smut, leaf scald, mosaic, and rust, in inoculated field experiments and under conditions of natural infection as part of the variety selection program to develop agronomically superior varieties with acceptable disease resistance. Two varieties, L 99-226 and L 99-233, were released during 2006. Tolerance to billet planting also was evaluated as part of the variety selection program. L 99-233 was identified as the only current commercial variety exhibiting consistent tolerance to billet planting. Yield loss caused by brown rust, smut, and yellow leaf were evaluated in field experiments. Brown rust, caused by Puccinia melanocephala, induced losses ranging from 4.7 (17%) to 5.7 (20%) tons of cane per acre in variety LCP 85-384. Smut, caused by Ustilago scitaminea, reduced millable stalk population in L 97-128. Yellow leaf, caused by Sugarcane yellow leaf virus, reduced both cane tonnage and sucrose yield of HoCP 96-540 by more than 10%. Fungicides were identified that reduce the severity of brown rust. Combinations of a strobilurin and triazole fungicide provided the best control with a combination of pyraclostrobin and tebuconazole providing the most consistent efficacy. Based on the research results, an application for a Section 18 Emergency Use label was submitted to EPA for three fungicide combinations: pyraclostrobin + metconazole, pyraclostrobin + tebuconazole, and trifloxystrobin + propiconazole. Ratoon stunting disease (RSD) testing of samples from 113 fields on 23 farms detected RSD on 13% of the farms and in 4% of the fields. However, the average infection level per field was less than 1%. RSD, caused by Leifsonia xyli subsp. xyli, and yellow leaf were monitored in commercial seedcane fields as part of the seedcane certification program. RSD was not detected, and yellow leaf did not exceed the certification standard of 10% infection in any field. A local quarantine was conducted to provide healthy plant material to initiate Foundation Stock plants to serve as a source for micropropagation of commercial seedcane for the Louisiana sugarcane industry.
IMPACT: 2006/01/01 TO 2006/12/31
A severe epidemic of brown rust occurred in Louisiana sugarcane during 2006. A yield loss study conducted for a third consecutive season confirmed that brown rust can cause losses of cane tonnage and sucrose of 17-20%. Fungicides were identified that reduce brown rust severity and increase yield. An application for a Section 18 Emergency Use label was submitted to EPA for three fungicide combinations. Fungicides have not been used previously for brown rust control. Two new varieties with resistance to brown rust, L 99-226 and L 99-233, were released during 2006. Resistant varieties should reduce the impact of brown rust, and current research suggests that a fungicide disease management program may be feasible for controlling rust in susceptible varieties. Yield losses demonstrated due to smut and yellow leaf indicate that a healthy seedcane program is essential for successful sugarcane production. Pathology research supports a healthy seedcane program based on certification of commercial seedcane produced via micropropagation. A local quarantine provides healthy plant material to start the process, and disease monitoring insures that diseases do not contaminate the seedcane sources and commercial farming operations. Ratoon stunting disease (RSD) testing indicates that RSD has been reduced to a minor problem by the public and private sector partnership that provides healthy seedcane to Louisiana farmers.
PUBLICATIONS: 2006/01/01 TO 2006/12/31
1. Gravois, K., Bischoff, K., Reagan, T.E., Hoy, J., and Kimbeng, C. 2006. L 99-226 and L 99-233: Two new sugarcane varieties for Louisiana's sugar industry. La. Agric. 49(3):23-25.
2. Hoy, J. 2006. The importance of a healthy seedcane program and disease testing. Sugar Bull. 85(1):13-14.
3. Hoy, J., and Hollier, C. 2006. Clipping as a possible rust control measure. Sugar Bull. 84(4):14-15.
4. Hoy, J.W., Arceneaux, A.E., and Savario, C.F. 2006. Effects of date and rate of billet planting on sugarcane yield. J. Amer. Soc. Sugar Cane Technol. 26:116-124.
5. Hoy, J.W., and Grisham, M.P. 2006. Effects of harvester type, inoculum source, and cultivar on spread of ratoon stunting disease. Sugar Cane Int. 24(3):3-6, 13.
Name: Hoy, J. W.