Progress 10/01/06 to 12/31/09
Outputs
OUTPUTS: Dissemination of project results to other scientists was done by presentations in poster format. One presentation was made at the American Phytopathological Society (APS) annual meeting help in St. Paul, MN and another e presentation was made at the Southern Nursery Association (SNA) Research Conference held in Atlanta, GA. The third presentation was made at Tennessee State University (TSU)-wide research symposium in Nashville, TN. The APS meetings have approximately 1500 participants, and SNA Research Conference had approximately 150-200 participants. Display of project results at these meetings disseminated project results to a total of 1650-1700 meeting participants. The TSU symposium was open to all departments and students. Abstracts from APS presentations were published in APS Phytopathology Journal supplement open to anyone with an internet access, thus providing an international dissemination. Most extension specialists from the southern region attend SNA research conference and these specialists would disseminate information from the conference to growers in their counties. The SNA research conference proceedings are online, open to all growers through the internet. The SNA research conference was also linked to the Southern Nursery Association trade show and provided an opportunity for thousands of growers and landscape specialists attending the SNA trade show to view the posters in display. PARTICIPANTS: Collaborators include: USDA-ARS scientist Dr. Sandra Reed, Otis Floyd Nursery Research Center, McMinnville , TN.; Drs M.T. Windham, and Y. Li of the University of Tennessee, Knoxville, TN. TARGET AUDIENCES: Presentations on multiple disease resistance in garden hydrangea was targetting nursery growers to provide them with information that will help them make informed decisions on cultivars they chose to grow. Target audience also included plant breeders to provide them with information on sources of disease resistance that can be used in breeding for resistance. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Out of 78 commercial cultivars evaluated for disease resistance in full sun and 73 evaluated under 60% shade clothe, some cultivars were resistant to powdery mildew and some were resistant to leaf spot and leaf blight diseases while a few had multiple disease resistance to both powdery mildew and leaf spot/leaf blight diseases. Results from this project also showed that leaf spot and leaf blight diseases were more prevalent in full sun than in shade while powdery mildew did not develop in full sun until late in the season when plants were nearing senescence. Some pathogens such as Phoma leaf spot were more prevalent in shade than in full sun and other pathogens such as cercospora, Corynespora and Glomerella were more prevalent in full sun. Different pathogens were identified with a description of symptoms they produced on hydrangea plants. Such results will be useful in breeding for disease resistance. Outcomes from this project include information on names of cultivars and their disease reaction powdery mildew and leaf spots/leaf blight diseases. This information will impact the development of multiple disease resistance to leaf blight/leaf spots and powdery mildew and the development of hydrangea plants that have desirable plant characteristics including size of plant and consumer preferred flowers combined with disease resistance. The biggest impact of project results is that growers can uses these results to make informed decisions on choices of cultivars they produce that will not require fungicide applications. Data generated from the project was a good indicator for project success.
Publications
- Mmbaga, M. T., Windham, M.T. and Li, Y. and Sauve, R.J. 2009. Fungi associated with naturally occurring leaf spots and leaf bights in Hydrangea macrophylla in McMinnville, Tennessee. Southern Nursery Association Res. Conf. Proceed. 54:1-5.
- Mmbaga, M. T., Li, Y., Sauve, R.J. and Windham, M.T. 2009. Leaf spots and Leaf blight disease complex in Hydrangea macrophylla. Phytopathology Journal Supplement. 99:87.
- Mmbaga, M. T. and Sauve, R.J. 2009. Foliage Diseases of Big leaf Hydrangea in Tennessee. 1890 Association of Research Directors Research Symposium Proceedings P146, pg 186.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Results from this project were communicated to other scientists in form of presentations made at professional meetings and journal articles. These included the annual meeting of the American Phytopathological Society (APS), and the Southern Nursery Association (SNA) Research Conference where project results were presented in three posters. The APS meetings have approximately 1500 participants, and SNA Research Conference had approximately 150-200 attendees. Display of project results at these meetings communicated project results to a total of 1650-1700 meeting participants. Abstracts from APS presentations were published in APS Phytopathology Journal supplement; anyone with an Internet has access to the abstracts. SNA Research conference was held at the same time, as the Southern Nursery Trade shows attended by thousands of growers from all over the United States. Poster presentation at SNA conference displayed project results to nursery growers and landscape specialists attending the Nursery Trade show. One Journal article has been published in HortScience Journal, and a second article is under preparation. In addition, a presentations to the Nursery Advisory Group of 6-12 growers communicated research results to Mid-Tennessee grower representatives. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nursery growers, landscape industry and Extension personnel PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Identification of powdery mildew resistance was repeated and resistant cultivars were evaluated to confirm initial results. In addition to evaluation for powdery mildew resistance, fungi associated with leaf blight and leaf spot diseases in hydrangea were identified in plants grown in full sun and in shade. Four fungi were associated with leaf blights and leaf spots and pathogenicity was confirmed; three of the fungi were new pathogens that have not been reported on hydrangea. The leaf blight/ leaf spot were considered a disease complex in that the symptoms were associated with several pathogens and it was difficult to separate disease severity caused by different organisms. Resistance to leaf blights and leaf spots was identified. Information on disease resistance will allow growers to make informed decisions on cultivars they grow. Production of disease resistant cultivars does not require fungicide applications, resulting in lower production costs and financial gains to growers. Project outcome/impact includes information availability to growers and communication of such information to clienteles. Presentation of research results to growers, extension agents and other scientists contributed to project outcome/impact. Project evaluation included availability of research results for meeting presentations and publications in journal articles and meeting abstracts and proceedings. One publication and one presentation per year were projected for project evaluation and results of two presentation and two publications exceeded expectations. Resources and activities that helped to produce project outputs included availability of funds for work-study laboratory assistants to assist in the research and travel funds for meeting presentations. One laboratory assistant was trained to conduct research activities and help in the project.
Publications
- Li, Y., Windham, M., Trigiano, R., Windham, A., Reed, S.M., Mmbaga, M., Spiers, J.M., Rinehart, T.A. 2007. Resistance to Powdery Mildew in Hydrangea. Hortscience. pp.919-1022
- Mmbaga, M.T., Reed, S.M., Windham, M., Yonghao, L. and Rinehart, T.A. 2008. Disease resistance in commercial cultivars of Hydrangea macrophylla. Phytopathology.98: 108
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: A total of 73 commercial cultivars of Hydrangea macrophylla were planted in 11.35 L (3 gal) pots. Two sets of plants were planted; one set was maintained under full sun to favor the development of cercospora leaf blight and the second set of plants was maintained under 60% shade clothe to provide good environment for powdery mildew. Each cultivar was replicated by three individual plants, arranged in a randomized complete block design. Plants were watered by drip irrigation and fertilized following recommendations for hydrangea. The 2007 was exceptionally hot and plants maintained under the full sun suffered severe leaf scotching. Thus, the evaluation for resistance to Cercospora leaf blight was discontinued because it was difficult to separate symptoms caused by the extreme heat from that caused by pathogens such as Cercospora. Plants under shade clothe developed powdery mildew (Erysiphe polygoni) naturally from airborne inoculum. Although powdery mildew was the main
disease observed, leaf blight and flower blight were also observed. Several fungi were isolated from the symptomatic leaves including Colletotrichum, Alternaria, Cercospora, and Botryosphaera species. However, some of the leaf blights may be associated with the extraordinary heat stress. Pathogenicity tests have been initiated, but the associations of particular leaf blight/leaf spot symptoms with specific fungi have not yet been confirmed. Powdery mildew disease was uniform throughout the shadehouse and disease severity was evaluated on a scale of 0-10 with 0 = no infection and 10 being 100 percent of the foliage showing disease symptoms. Powdery mildew infection started in July in a few cultivars, but by early August the infection was observed throughout the shadehouse. While most of the cultivars were susceptible to powdery mildew, variation in susceptibility was observed and few cultivars displayed resistance to powdery mildew. Some cultivars were characterized as early mildewing
in that they developed disease symptoms earlier than others with 90% of their leaves covered with powdery mildew symptoms by mid August. Some cultivars were also characterized as slow mildewing in that they remained resistant to powdery mildew throughout August and September and severe infection developed very late in the season when plants normally shed their leaves. High susceptibility to powdery mildew is normally associated with premature defoliation, but the extreme heat experienced in 2007 and the associated leaf blights may have contributed to the premature defoliation observed. Some cultivars displayed host resistance with 0-10 percent of their foliage showing powdery mildew symptoms, and other cultivars had symptoms on 30-50 percent of the foliage. A total of 15 cultivars displayed some resistance to powdery mildew with less than 50 percent of their foliage showing disease symptoms throughout the season
PARTICIPANTS: USDA Plant Breeder located at the TSU Research Center; University of Tennessee Plant Pathologists and Cooperative Extension are collaborators in this project.
TARGET AUDIENCES: Results from this project will provide information to growers and Cooperative Extension scientists who may recommend cultivars suitable in the mid Tennessee area.
PROJECT MODIFICATIONS: Objective (3) Survey mid-Tennessee nurseries and landscape areas and identify soil-borne pathogens that impact ornamentals has been removed because it has an overlap with another project funded by CSREES-Capacity Building Grants.
Impacts
Identified disease resistant hydrangeas can be produced without the need to use fungicides to control diseases. Resistance to multiple diseases is particularly important and will reduce production costs and increase grower net profit from hydrangea plant sales. The identified resistant cultivars provide disease resistance sources for breeding programs to combine disease resistance with other desirable traits.
Publications
- Li, Y., Windham, M.T., Trigiano, R.N., Windham, A.S., Reed, S.M., Mmbaga, M.T., Spiers, J.M. and Rinehart, T.A. 2007. Resistance to Powdery Mildew in Hydrangeas. Southern Nursery Association Res. Conf. (In Press)
- Windham, M, Mmbaga, M.T., Reed, S., Rinehart, T., Windham, A.S. and Li, Y. 2007. Evaluation of Hydrangea Cultivars for Resistance to Powdery Mildew. Southern Nursery Association Res. Conf. (In Press)
- Li, Y., Windham, M.T., Trigiano, R.N., Windham, A.S., Reed, S.M., Mmbaga, M.T., Spiers, J.M. and Rinehart, T.A. 2007. Resistance components of Hydrangea to Powdery Mildew. Phytopathology 97: S64:
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Progress 01/01/06 to 12/31/06
Outputs
The purpose of this project was to (1) identify disease resistance to powdery mildew and Cercospora leaf spot/blight in commercial cultivars of Hydrangea macrophylla. (2) Evaluate biopesticides for controlling powdery mildew and Cercospora leafspot/blight. (3) Survey mid-Tennessee nurseries and identify soil-borne pathogens that impact hydrangea production. Cultivars have been collected and planted in plastic containers for shadehouse experiments. Propagation of the cultivars has been done. The project objectives will start in summer 2007.
Impacts
Identification of Hydrangea cultivars that have multiple disease resistance will reduce fungicide use and production costs and increase grower income from plant sales. Identification of biopesticides for controlling hydrangea foliar diseases will also reduce fungicide use, production costs and accidental pesticide exposures. This will have economical and environmental benefits. Information on the prevalent soil borne pathogens in Tennessee will facilitate the development of disease management strategies that target important pathogens.
Publications
- No publications reported this period
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