Link to home

Andrea Ficke, Lisa Hoffman, and Megan Kennelly

Andrea Ficke, Lisa Hoffman, and Megan Kennelly received their undergraduate degrees from Georg-August University in Goettingen, Germany; the University of Delaware; and the University of Wisconsin-Madison; respectively. All received their Ph.D. degrees from Cornell from 2001 to 2005 as students in the Department of Plant Pathology at the New York State Agricultural Experiment Station in Geneva. Ficke is presently a cereal pathologist at the Norwegian Institute for Agricultural and Environmental Research, Hoffman is a new product development manager with DuPont Crop Protection, and Kennelly is an associate professor in the Department of Plant Pathology at Kansas State University.

Ficke, Hoffman, and Kennelly worked together in exemplary fashion as Ph.D. students within a research team at Cornell University’s New York State Agricultural Experiment Station at Geneva between 1998 and 2005 and published a series of 13 papers in Phytopathology, Plant Disease, and Plant Health Progress between 2001 and 2007 that profoundly affected the management of three of the most destructive diseases of grapevine: powdery mildew (Erysiphe necator), black rot (Guignardia bidwellii), and downy mildew (Plasmopara viticola). They worked together within the same vineyards; shared techniques and protocols; discussed, critiqued, and refined each other’s research; and cooperated in the complex studies required to simultaneously investigate ontogenic resistance to multiple diseases at the field level. The European grape species (Vitis vinifera) is valued for production of the highest quality wines. Planting V. vinifera throughout the United States placed a nonnative host of near-universal susceptibility within the center of origin of the above pathogens. Export of the above pathogens throughout viticultural areas worldwide has likewise created a production system within which fungicides are an inevitable and critical component of management programs. Application timing is driven by the need to suppress disease during peak periods of host susceptibility, inoculum production, and environmental favorability. The above team contributed new knowledge on each of these fronts that markedly improved management programs worldwide.

Andrea Ficke explored the onset of ontogenic resistance to powdery mildew in developing grape berries. Pioneering work in which Ficke played a major role (Phytopathology 91:948-955 and 93:547-555) had shown that berries became highly resistant to infection far earlier than previously thought. Later work lead by Ficke (Phytopathology 93:556-563 and 94:438-445) produced a number of important findings: it showed that ontogenic resistance (a) stopped pathogen ingress at the interface of the cuticle and epidermis, (b) precisely delimited the time of pathogen death, (c) elucidated the anatomical and biochemical mechanisms involved in ontogenic resistance, and (d) ultimately showed that the response was sufficiently consistent and predictable to serve as the basis for a revision of management programs for grapevine powdery mildew worldwide (Phytopathology 92:671-675). Ficke’s elegant experiments demonstrated the lack of the role of several pathogenesis-related proteins and secondary metabolites to ontogenic resistance that were thought to play a role, as they were produced too late or in the wrong tissues to effect an epidermal pathogen (Phytopathology 94:438-445) and, thereby, redirected and refocused fundamental studies searching for the mechanism of ontogenic resistance. In the most recent work, a team including Ficke demonstrated how cryptic mildew colonies established just before the complete development of ontogenic resistance can produce a cascade of effects that can substantially degrade wine quality (Phytopathology 97:1356-1365).

Lisa Hoffman’s contributions were made in a series of parallel studies of ontogenic resistance and inoculum dose in the epidemiology of black rot. As in the case of grapevine powdery mildew, little was known about the period of fruit susceptibility to black rot, and this often resulted in substantial and seemingly unexplainable losses. Work lead by Hoffman clearly delineated not only the period of berry susceptibility (Phytopathology 92:1068-1076) but also the period of inoculum availability and how sanitation and spray timing could be optimized based upon her discoveries (Phytopathology 94:641-650 and Plant Disease 87:273-281). Her comprehensive work has been of great value to growers throughout the eastern United States, where the disease is both endemic and severe, and also in several European countries, where the disease has more recently become destructive.

As a fellow Ph.D. student with Ficke and Hoffman, Megan Kennelly embarked on a multifaceted investigation of grapevine downy mildew. The overarching goal of her work was to provide the biological basis for an improved forecasting model for advisory systems. This necessitated exploring the development of ontogenic resistance in grape berries to P. viticola (Phytopathology 95:1445-1452). As in the case of powdery mildew and black rot, this process was poorly understood before Kennelly’s study. The seasonal dynamics, mechanisms involved, and differential response of berry as compared to rachis tissue proved to be substantially different from either powdery mildew or black rot. Kennelly’s work clearly demonstrated a very brief period of extreme berry susceptibility, hence a critical and narrow window of opportunity to suppress fruit infection. Her additional findings related to multiseason survival of oospores, the relationship between sporulation and the cyclical decline of lesion productivity, and host phenology and early-season disease development (Phytopathology 97:512-522) all resulted in improvements to downy mildew forecasting systems (Plant Heath Progress doi:10.1094/PHP-2007-0726-03-RV).

The impact of the collective work of Ficke, Kennelly, and Hoffman has been felt worldwide. Indeed, there are few disease management programs today that do not incorporate their findings. The research was made widely available in a timely fashion through prolific publication in APS refereed journals and active participation in the International Workshops on Grapevine Powdery and Downy Mildew. It is significant to note that all three former students were selected to present their work to APS as distinguished speakers in the I. E. Melhus Graduate Student Symposia (Phytopathology 92:671-675, Phytopathology 92:676-680, and Plant Heath Progress doi:10.1094/PHP-2007-0726-03-RV). All three nominees are well known and respected for the work described herein, for its impact upon production agriculture, and for the model for which these studies served in graduate education. Aspects of their work have benefited subsequent fundamental research by spatially and temporally isolating the phenomenon of ontogenic resistance. They are especially deserving of recognition by APS as recipients of the Lee M. Hutchins Award.