Source: TENNESSEE STATE UNIVERSITY submitted to NRP
DISEASE MANAGEMENT IN NURSERY PRODUCTION OF WOODY ORNAMENTALS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
EVANS-ALLEN
Reporting Frequency
Annual
Accession No.
0223672
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Jan 1, 2010
Project End Date
Sep 30, 2014
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
TENNESSEE STATE UNIVERSITY
3500 JOHN A. MERRITT BLVD
NASHVILLE,TN 37209
Performing Department
Agricultural and Environmental Sciences
Non Technical Summary
The Tennessee State University Nursery Research Center has the mandate to address nursery production problems with a focus on woody ornamental plants. Tennessee is the main supplier of dogwood plants (Cornus spp.) in the United States and problems that reduce sales or increase production costs reduce grower net income with a strong ripple effect on Tennessee economy. The nursery industry relies heavily or totally on chemical pesticides to combat disease and pest problems. According to 1998 Tennessee agricultural statistics, farm production expenses on pesticides ranked second after fertilizers and cost $105 million. Regulatory challenges focused on water quality issues, worker protection standards and chemical use regulations place increasing pressure on growers to conserve natural resources and the environment. It is thus important to develop alternatives to traditional fungicides and provides practical solutions that are environmentally friendly. Improved strategies for powdery mildew disease management will have great impact on the entire southeastern region of the United States where powdery mildew is the most important constraint in dogwood production. Powdery mildew disease is the most important disease impacting dogwood production; it reduces plant aesthetic value and stunts plant growth. Severe infections cause early leaf senescence and reduced flower buds. Routine application of fungicides is the main method for controlling powdery mildew starting at bud break and continues season-long at 7-14 days interval depending on the fungicide and disease pressure. There is need to find alternatives to conventional fungicides for economic and environmental reasons. Compounds designated as `biorational' or biopesticides are regarded as relatively harmless to the environment and non-target organisms and they are relatively cheaper than conventional pesticides. The US Environmental Protection Agency defines biopesticides as a pesticide derived from natural materials like plants, bacteria/microorganisms, and certain minerals. Our previous studies have shown that using 3:1 rotations of biopesticides with a conventional fungicide reduced fungicide usage by 56-66% and provided powdery mildew control similar to conventional fungicide alone. Our previous studies have also identified microorganism that are effective in powdery mildew control. Before these organisms can be developed into microbial pesticides, more studies are needed to understand their mechanism of action, identify synergistic organisms and enhance disease control and best application method. This project will advance previous studies on biological control of powdery mildew. The goal of this project objective is to develop a biological-based integrated disease management system for dogwood production that incorporates powdery mildew resistance and biopesticides. While two powdery mildew resistant selections have been tested at multiple locations in replicated trials for new cultivar releases, evaluation for resistance will continue to identify additional material that can add to new generation of disease resistant cultivars.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1242110113050%
1244099116050%
Knowledge Area
124 - Urban Forestry;

Subject Of Investigation
4099 - Microorganisms, general/other; 2110 - Ornamental trees and shrubs;

Field Of Science
1130 - Entomology and acarology; 1160 - Pathology;
Goals / Objectives
The main objective of this project is to develop disease management strategies with emphasis on environmentally friendly methods. The following are specific objectives: (1) Transfer results from previous research to growers. (2) Advance the identification and evaluation of microorganisms for biological control of powdery mildew and,(3) Continue the identification of host resistance as the ultimate alternative to conventional fungicides in disease management.
Project Methods
Objective (1) Transfer results from previous research to growers: Previous research identified a number of compounds that wee effective on powdery mildew disease management; two commercial products and two non-registered products were as effective as commercial pesticides in reducing disease severity. Demonstrations of the product efficacy to growers will be done in organized Field Days. Two Field days will be held per year at two locations, one at the Research Center Fields, centrally located in Warren County and one at a commercial nursery location outside Warren County. Educational brochure developed for this project will be provided and Field Day participants will receive pesticide points for pesticide certification. The Field Day will be open to all who may wish to attend from Tennessee producers, and surrounding states. Demonstrations to growers will include four commercial biopesticides, Triact 70 (clarified hydrophobic extract of neem oil [70%]) and Armicarb 100 (Sodium bicarbonate) and two non-registered products, household soaps Ajax and Palmolive and showcase the use of biopesticides in fungicide rotations to reduce the amount of conventional fungicide and reduce costs in powdery mildew disease management. Information delivered to Growers will include distribution centers for the commercial biopesticides, prices and efficacy. The release of two powdery mildew resistant cultivars for commercial production will be announced and presentation on the new cultivars will be made during the field days. Change in grower practice to start incorporating biorationals/biopesticides in fungicide rotations will be the main output of this objective and a good measure of knowledge gained from this project. The monetary savings from these rotations and modification in grower practice will be measured by using a questionnaire at the end of the project. Objective (2) Advance the identification and evaluation of microorganisms for biological control of powdery mildew: Biological based organisms including yeast in the genera Cryptococcus spp. and Sporobolomyces and bacteria in the genus Bacillus, showed potential for controlling powdery mildew. Although such organisms colonize plant leaves as saprophytes, they have been reported to act as antagonists of plant pathogens. Previous results suggest that the selected organisms may have different mechanisms of action, including mycoparasitism, antibiosis, and induced host resistance. The proposed research will focus on mechanism of action and identification of synergistic interactions that may be used to enhance efficacy in powdery mildew control. Results will be analyzed by using SAS. Objective (3) Continue the identification of host resistance in flowering dogwood: Selections of flowering dogwood for powdery mildew resistance have been made. While two selections have been tested in multiple locations in replicated trials are ready for cultivar release, evaluation for resistance will continue to identify additional material that can add to a new generation of disease resistant cultivars. Results of disease resistance measured by disease severity will be analyzed using SAS.

Progress 01/01/10 to 09/30/14

Outputs
Target Audience: Nursery growers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Three graduate students and one undergraduate student worked on the project. Sponsorship for students to attend the American Phytopathological Society annual meetingto present their work was a great learning experience for three students. How have the results been disseminated to communities of interest? In form oforal presentations to clintele, nursery-related publication, professional meeting presentations and journal publications What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? A workshop was held at the Otis Floyd Research Center, nursery growers as well as extension agents from different counties in Tennesseeparticipated in the workshop. Presentations included (1) system-based plant production in commercial nurseries to reduce agrichemicals, (2)new and emerging diseses and pests in nursery production of woody plants(3) New and safer technologies and chemistries for controlling woody ornamental pests, (4) research results on biological agents for disease control and (5) research results on disease resistance to powdery mildew of dogwood. Advancment of research on microorganisms for biological control of powdery mildew included mechansisms of action of three selected biocontrol agents and their effect on diverse soil-borne pathogens . Research advanvencement on host resistance to powdery mildew focused on genetics studies and evaluation of inheritance mechanism.

Publications

  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2014 Citation: Jacqueline Joshua and Margaret T. Mmbaga 2014. Perpetuation of Cherry Leaf Spot Disease in Ornamental Cherry. Phytopathology J. doi: 10.1111/jph.12309. Mmbaga M.T, T. Simmons, L. Mackasmiel2 and J.O. Joshua 2014. Microbial Diversity in Dogwood Seeds and Their Role as Pathogens and as Biocontrol Agents. Res Conf. Proceed. Southern Nursery Assoc Vol. 59: In Press. Mackasmiel L.A and M.T Mmbaga . 2014 Sources of Phytophthora Species and Other Pathogens in Middle Tennessee Nurseries. Res Conf. Proceed. Southern Nursery Assoc. Vol. 59: In Press Lipi Parikh, S. Kodati, M. T. Mmbaga and Gurong Zhang 2014. Inheritance of powdery mildew resistance in flowering dogwoods (Cornus florida L.)Res Conf. Proceed. Southern Nursery Assoc. Vol. 59: In Press Rotich, Emily, Margaret T. Mmbaga and Parama Sikdar 2014. Characterization of Bacterial Biocontrol Agents for Management of Selected Fungal Pathogens in Cornus florida. Res Conf. Proceed. Southern Nursery Assoc. Vol. 59: In Press Mackasmiel�, L. A., and Mmbaga�, M. T. 2014. (abst). Major Source of Phytophthora Species and Other Pathogens in Middle Tennessee Nurseries. Tennessee State Unive. Unversity-wide Res. Sympsium Mmbaga, Margaret, T. Simmons, L. Mackasmiel2 and J.O. Joshua 2014 (Abst). Microbial Diversity in Dogwood Seed and potential applications. Tennessee State Unive. Unversity-wide Res. Symposium


Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Nursery Growers Scientific community Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Two students worked on the project , one on dogwood and one on flowering cherry How have the results been disseminated to communities of interest? A workshop on Nursery disease and pest management held at the Otis Floyd Nursery Research Center in McMinnville, TN. had presentations on disease identification in nurseries and increasing safety in nursery disease management. Presentations at the Southern Nursery Association Research conference covered the control of cherry leaf spot disease in flowering cherry, and controlling powdery mildew disease in dogwood by using biological agents and by using host resistance had nursery growers who were participating in nursery trade show.nursery trade show (approx. 450 nurseries participated in the nursery trade show. What do you plan to do during the next reporting period to accomplish the goals? Contnue research objectives, confirm previous results and continue training studetns on disease managment and plant pathology research.

Impacts
What was accomplished under these goals? During this reporting time research results were transferred to growers using a workshop that targeted nursery growers as the main audience. The workshop on Nursery disease and pest management held at the Otis Floyd Nursery Research Center in McMinnville, TN. had presentations on disease identification in nurseries and increasing safety in nursery disease management. Presentations on controlling cherry leaf spot disease in flowering cherry, and controlling powdery mildew disease in dogwood by using biological agents and by using host resistance were also made at the Southern Nursery Association Research Conference in Atlanta, GA where approx. 450 nurseries participated in a nursery trade show. Presentations at the American Phytopathological Society annual meeting transferred research results to the scientific community; presentations made at Tennessee State University-wide symposium shared research information with students and faculty within the University. Another form of dissemination of research results was in form of publications; conference proceedings and published meeting abstracts listed below; three journal manuscripts were submitted for journal publication and are still in review. Two graduate students worked on objective 2, one student worked on objective 4 and one student worked on objective 5.

Publications

  • Type: Journal Articles Status: Under Review Year Published: 2013 Citation: Mmbaga, M.T.; Mrema, F.A.; Mackasmiel, L. and Rotich E. Bacterial bio-control agents for powdery mildew in flowering dogwoods (Cornus florida L.) Submitted to International Journal of Biological control Joshua Jacqueline O. and Mmbaga Margaret T. Perpetuation of Cherry Leaf Spot Disease in Ornamental Cherry . Submitted to Journal of Phytopathology. Mmbaga, M.T; Kim, M.; SHI, A.; Mackasmiel, L.; and Klopfenstein, N.B. Differentiation of Corynespora cassiicola and Cercospora sp. in leaf-spot diseases of Hydrangea macrophylla using morphological and PCR-mediated methods. Submitted to Journal of Phytopathology.


Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: The main objective of this project is to identify diseases that impact nursery production system and develop disease management strategies with emphasis on environmentally friendly methods. The following are specific objectives: (1) Transfer results from previous research to growers. (2) Advance the identification and evaluation of microorganisms for biological control of powdery mildew in dogwood (3) Evaluate additional compounds for potential as biopesticides in disease management of powdery mildew and other foliage diseases. (4) Identify foliage diseases that are of concern to nursery growers and (5) continue the identification of host resistance as the ultimate alternative to conventional fungicides in disease management. During this reporting time objectives 2, 4 and 5 were addressed. Results were presented at the Southern Nursery Association Research conference, the American Phytopathological Society annual meeting and Tennessee State University wide symposium. Two graduate students worked on objective 2, one student worked on objective 4 and one student worked on objective 5. Results from the project were disseminated in nine presentations made in professional meetings and to nursery industry related conferences. Three presentations were made at the Southern Nursery Association Research Conference held at Mobile AL. Thus, nurserymen from Tennessee, the southern and Gulf States and nursery trade show attendees were exposed to our research findings on biological agents for disease control and cherry leaf spot disease management in ornamental flowering cherry. Two presentations were made at the American Phytopathological Society annual meeting and information from this project was shared with the scientific community. Four presentations were made at Tennessee State University wide symposium and shared information with students and faculty within the University. Another form of dissemination of research results was in form of publications; two conference proceedings and six published abstracts are listed below; one journal article was also published and two have been submitted for review. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
An important project outcome is on student training in which four students had experiential learning by their participation in the project execution. The research on biological control agents focused on two bacteria and their mechanism of action and effect on plant growth, on powdery mildew and root rot caused by Macrophomina sp. Results from this project have implications on the utilization of these biological agents in dogwood production and in promoting plant growth. Research on cherry leaf spot of ornamental flowering cherry confirmed previous results on winter survival of the cherry leaf spot pathogen. Utilization of these results is on devising strategies for improving the timing of fungicide applications, improve disease management, and subsequently improve the quality of trees, impact plant sales and grower incomes. A study on fungicide efficacy identified two fungicides that showed superior efficacy in controlling cherry leaf spot disease severity. Results from this project are already impacting cherry leaf spot disease control in grower's fields. Two growers we worked with in their fields had first hand benefit of our results and continues to play an important role in dissemination of our research results to neighboring nurseries and other growers in the southeastern states where these farmers market their plants. Resources provided for this project enabled us to hire research assistants and work-study students who achieved experiential learning and also enabled us to manage and complete specified project activities and facilitated project outcomes.

Publications

  • Mmbaga, M. T., Kim, M.S, Mackasmiel, L. and Li, Y. 2012. Evaluation of Hydrangea macrophylla for Resistance to Leaf-Spot Diseases. J. Phytopathol. 160:88-97.
  • Olson, H. A., Jeffers, S. N., Ivors, K. L., Steddom, K. C., Williams-Woodward, J. L., Mmbaga, M. T., Benson, D. M., and Hong, C. X. 2013. Diversityand mefenoxam sensitivity of Phytophthora spp. associated with the ornamental horticulture industry in the southeastern United States. Plant Dis. 97:86-92.
  • Joshua, J. and Mmbaga, M. T. 2012 (Abstr.). Management of Cherry Leaf Spot in Flowering Cherry (Prunus L. species). Univ wide workshop.
  • Mackasmiel, L. A. and Mmbaga, M.T.2012. Two bacteria effective against both Macrophomina root rot and powdery mildew in flowering dogwood. Proceed. Southern Nurs. Assoc. Res. Conf. 2012. Vol. 57:257-261
  • Lawrence, S. and Mmbaga, M.T. 2012. (Abstr.) Occurrence of endophytic microorganisms in flowering dogwood and their potential applications. 2012 TSU Univ. wide workshop. Rotich, E., Mmbaga, M.T. and Zheng, M. (Abstr.) Production of volatile products by potential biological control bacteria collected from flowering dogwoods. 2012 TSU Univ. wide workshop.
  • Rotich, E., Mmbaga, M. T. and Zheng, M. 2012 (Abstr.) Antifungal volatile production by potential biological control bacteria collected from flowering dogwoods. TSU Chemistry day.
  • Lipi, P., Mmbaga, M.T. and Zhang, G. 2012 (Abstr.) Resistance to powdery mildew in flowering dogwood plants. 2012 TSU Univ. wide workshop.


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: The main objective of this project is to identify diseases that impact nursery production system and develop disease management strategies with emphasis on environmentally friendly methods. The following are specific objectives: (1) Transfer results from previous research to growers. (2) Advance the identification and evaluation of microorganisms for biological control of powdery mildew in dogwood (3) Evaluate additional compounds for potential as biopesticides in disease management of powdery mildew and other foliage diseases. (4) Identify foliage diseases that are of concern to nursery growers and (5) continue the identification of host resistance as the ultimate alternative to conventional fungicides in disease management. During this reporting time objectives 2, 4 and 5 were addressed. Results were presented at the the Southern Nursery Association (SNA) Research conference, the American Phytopathological Society (APS) annual meeting and Tennessee State University wide symposium. Three students worked on objective 2, one student worked on objective 3 and one student worked on objective 5. Results from the project were disseminated in nine presentations made in professional meetings and to nursery industry related conferences. Three presentations were made at the Southern Nursery Association Research Conference held at Mobile AL. Thus, nurserymen from Tennessee, the southern and Gulf States and nursery trade show attendees were exposed to our research findings on biological agents for disease control and cherry leaf spot disease management in flowering cherry. Three other presentations were made at the American Phytopathological Society (APS) annual meeting and three at Tennessee State University wide symposium, where research results were displayed to the scientific community. Another form of dissemination of research results was in form of publications; three conference proceedings and six published abstracts are listed below, One journal article was also published. PARTICIPANTS: student training as experiential learning for four students. TARGET AUDIENCES include nursery producers. PROJECT MODIFICATIONS: Not relevant to this project. PARTICIPANTS: Nursery growers from Warren County, TN TARGET AUDIENCES: Nursery gowers for ornamental plants PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
(1)Our research on biological control agents focused on methods of application with two biological control bacteria and two fungi. This was a second year evaluation to confirm results from last year. Drenching of seedlings with two bacteria and two fungi was as effective as foliar spray against powdery mildew in dogwood seedlings and endophytic occurrence of two bacteria and a fungus was confirmed. In addition, two bacteria were found to be effective in controlling macrophomina root rot and boosting plant growth. These findings have implications on the utilization of these biological agents in dogwood for powdery mildew management, macrophomina root rot control that perhaps contributed to the increased plant growth. Mode of application in the soil suggests that they may be applied by seed treatment; their effect on other soil-borne pathogens is being evaluated. (2)Research on diseases of economic concern to growers focused on cherry leaf spot of flowering cherry in which results on effective fungicides and the timing of disease establishment were confirmed. This information is important to guide growers on the timing of fungicide applications. Four fungicides; two newer formulations and two older copper based fungicides were evaluated individually and in rotations; they were all highly effective in controlling cherry leaf spots, shot holes and defoliation. Previously infected plants developed infection in greenhouse environment where they were protected from airborne sources of infection. These results confirmed that cherry leaf spot may overwinter in the dormant buds and be the source of infection in spring. The impact of our research findings is on growers who are now able to control cherry leaf spot disease, by proper timing of fungicide applications and by avoiding plant propagation from previously infected plants. The effective control of cherry leaf spot in flowering cherry was evident in the increased plant growth and market value of this popular ornamental plant. Two growers we worked with in their fields had first hand benefit of our results and continues to play an important role in dissemination of our research results to other growers in the southeastern states where these farmers market their plants.

Publications

  • Joshua, J., Mmbaga, M.T. and Mackasmiel, L.A. 2011. Perpetuation of Cherry Leaf spot disease in flowering cherry. Proceed. SNA Research Conference Vol. 56 (In Press)
  • Mackasmiel, L. A., and Mmbaga, M. T. 2011. Efficacy and methods of application of biological control agents against powdery mildew in dogwood. Proceed. SNA Research Conference Vol. 56 (In Press)
  • Kilbourne, K., Mmbaga, M. and Harrison, R. 2011. Spatial analysis of Phytophthora diseases in nursery production system in Warren County, TN. Proceed. SNA Research Conference Vol. 56 (In Press)
  • Kilbourne, K., Mmbaga, M. and Harrison, R. 2011. (Abstr). Severity Risk Spatial Model for Phytophthoradiseases in Woody Ornamental Nurseries in Southern Middle Tennessee. Phytopathology (June Suppliment).
  • Mackasmiel, L. A., and Mmbaga, M. T. 2011. (abstr) . Powdery Mildew Biological Control Agents Exhibit Endophytic Characteristics. Phytopathology (June Suppliment).
  • Joshua, J., Mmbaga, M.T. and Mackasmiel, L.A. 2011. (Abst) Cherry Leaf Spot Disease Management in Ornamental Flowering Cherry. Phytopathology (June Suppliment).
  • Mmbaga, M.T. and Macksmiel, L. 2011. (Abstr). Morphological and molecular diagnosis of Corynespora cassiicola and Cercospora sp. causal agents for hydrangea leaf spot diseases. Phytopathology. June Suppliment
  • Mmbaga, M.T., Kim, M., Mackasmiel, L. and Li, Y. 2011. Evaluation of Hydrangea macrophylla for Resistance to Leaf-Spot Diseases. J Phytopathol 160:88 to 97 (2012)


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: The main objective of this project is to identify diseases that impact nursery production system and develop disease management strategies with emphasis on environmentally friendly methods. The following are specific objectives: (1) Transfer results from previous research to growers. (2) Advance the identification and evaluation of microorganisms for biological control of powdery mildew in dogwood (3) Evaluate additional compounds for potential as biopesticides in disease management of powdery mildew and other foliage diseases. (4) Identify foliage diseases that are of concern to nursery growers and (5) continue the identification of host resistance as the ultimate alternative to conventional fungicides in disease management. During this reporting time objectives 2, 4 and 5 were addressed. Results were disseminated in professional meetings including the Southern Nursery Association (SNA) Research conference, the American Phytopathological Society (APS) annual meeting and Tennessee State University wide symposium. Eight presentations were made, four at the Southern Nursery Association Research Conference where nurserymen from Tennessee, Georgia and the Gulf States were also holding their annual trade shows. Thus, nursery trade show attendees were exposed to our research findings. In addition, two presentations were made at the American Phytopathological Society (APS) annual meeting and two at Tennessee State University wide symposium, where research results were displayed to the scientific community. Another form of dissemination of research results was in publications eight listed below, including 2 published abstracts, four meeting proceedings and two journal articles. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
(1)Our research on biological control agents focused on methods of biocontrol application with two bacteria and two fungi. Drenching of seedlings with two bacteria and two fungi was as effective as foliar spray against powdery mildew in dogwood seedlings. These biocontrol agents were observed inside the plant roots indicating endophytic characteristics in treated plants. These findings have implications on the mode of application that may be used to enhance utilization of these biological agents in dogwood powdery mildew management. (2)Research on diseases of economic concern to growers focused on cherry leaf spot of flowering cherry in which effective fungicides and the timing of disease establishment were identified. This information is important to guide growers on the timing of fungicide applications. Four fungicides; two newer formulations and two older copper based fungicides were evaluated individually and in rotations; they were all highly effective in controlling the disease including control of leaf spots, shot hole and defoliation. Previously infected plants developed infection in greenhouse environment where they were protected from airborne sources of infection. In addition, six flowering cherry cultivars were evaluated for disease resistance to cherry leaf spot. Results need to be confirmed before passing to growers. The impact of our research findings is on growers who are now able to control the disease, have increased plant growth and market value of the popular ornamental flowering cherries. The impact was felt by the two growers we are working, sprayed plants grew more than twice as fast as non sprayed plants and all were ready for sale at a higher price than none sprayed plants. Dissemination of the results to other growers in the southeastern US will multiply the economic impact where the disease is important throughout the southeastern region.

Publications

  • Windham ,M. T. Reed, S. M., Mmbaga M. T., Windham A.S., Li ,Y. and Rinehart, T. A. 2011. Evaluation of Powdery Mildew Resistance in Hydrangea macrophylla J. Environ. Hort..29: (in Press).
  • Mmbaga, M.T., Li, Y. and Kim, M. S. 2010. First Report of Myrothecium roridum causing leaf pot in garden hydrangea. Plant Dis. Vol. 94. (10) 1266. http://dx.doi.org/10.1094/PDIS-04-10-0264.
  • Mmbaga, M.T., Li, Y. and Mackasmiel, L. 2010 (Abstr).Cercospora and Corynespora leaf spots in Hydrangea macrophylla. June Phytopathology Supplement.
  • Mmbaga, M.T., Mackasmiel, L. and Joshua, J. 2010 (Abstr). Leaf spot Disease in Ornamental Flowering Cherry Nursery Production. Phytopathology Supplement.
  • Mmbaga, M. T. . 2010. First Report of Myrothecium roridum causing leaf spot in Hydrangea macrophylla in United State. Southern Nursery Association Res. Conf. Proceed. 55: (In Press).
  • Mmbaga, M. T., Li, Y. H., Reed, S.M., Trigiano, R. and Windham, M.T. 2010. Phoma Leaf Spot in Bigleaf Hydrangea Southern Nursery Association Res. Conf. Proceed. 55: (In Press).
  • Mmbaga, M.T. 2010.Myrothecium roridum in Garden Hydrangea. Southern Nursery Association Res. Conf. Proceed. 55: (In Press).
  • Mmbaga, M. and Sauve, R. 2010. Leaf Spot Diseases on Ornamental Flowering Cherry Southern Nursery Association Res. Conf. Proceed. 55: (In Press).