Themis J. Michailides was born in Greece. After receiving his first M.S. degree in agriculture development and irrigation from the Agricultural University in Athens, Greece, he obtained M.S. and Ph.D. degrees in plant pathology from the University of California (UC), Davis. From 1984 to 1988, he was a post-doctoral research associate, first at Oregon State University at Hood River, and later at UC Davis. He served on the faculty in the Department of Plant Pathology, UC Berkeley, and in 1989 and was promoted to associate plant pathologist in 1992. With the transfer of ag-related research and extension programs from Berkeley to the Davis campus, Michailides was assigned to the Department of Plant Pathology, UC Davis. He is currently a plant pathologist at the Kearney Research and Extension Center with research responsibilities in fruit and nut crop diseases.
Michailides is a leading authority in fungal fruit tree pathology and is nationally and internationally recognized for his innovative ecological, epidemiological, and disease management studies of devastating diseases of fruit and nut crops, such as brown rot in stone fruit (preharvest and postharvest), Botrytis gray mold of kiwifruit and pistachio, fig endosepsis and smut of figs, Botryosphaeria blight of pistachio and almond, and aflatoxin contamination and reduction of contamination of nut crops and figs. Michailides’ earlier work on the effects of overpollination of Calimyrna figs in relation to the population dynamics of fig wasp pollinators (Blastophaga psenes) provided the basic understanding of the strong relationship between fig endosepsis caused by Fusarium moniliforme and the pollinator wasp. For the first time, the Michailides’ laboratory presented scientific evidence of harmful effects of overpollination, thus convincing fig producers to strive for optimum pollination, in order to reduce fig endosepsis disease of fruit. Michailides pioneered the work on conventional techniques to detect latent infection by pathogens, such as Monilinia fructicola in stone fruit, Botrytis cinerea in kiwifruit, and Botryosphaeria dothidea in pistachio, and predict diseases caused by these pathogens. His methods have been adopted by national and international private laboratories to predict disease risks. He was the first to perform cultural controls, such as irrigation manipulation and pruning to control panicle and shoot blight of pistachio, at a time when there were no effective fungicides registered on pistachio.
In addition to his highly effective applied research program, Michailides has made major contributions in fundamental plant pathology. Together with his team, he was the first to use conventional and quantitative PCR techniques to quantify latent infections on stone fruit and spore loads of Monilinia fructicola in orchards and incorporated the findings in computer models to predict brown rot of prune. A pioneering contribution of Michailides’ research project was the discovery of resistance mechanisms of Alternaria alternata to a strobilurin fungicide, in which azoxystrobin resistance correlated with a single mutation in the cytochrome b gene. He has developed an allele-specific PCR assay for a quick and accurate detection and quantification of azoxystrobin-resistant Alternaria populations in pistachio and almond orchards directly from plant tissues without the need to isolate the pathogen. Another major contribution was the discovery of resistance to the carboxamide boscalid within the second season of its commercial use. Michailides has discovered five-point mutation in three (SDHB, SDHC, and SDHD) out of the four subunits of the succinate dehydrogenase (SDH) gene. He was the first worldwide to show two point mutation in the subunit SDHD that also conferred resistance to boscalid and explained why resistance to this fungicide has developed so quickly since its first use. By using molecular approaches, Michailides has shown that populations of Botryosphaeria dothidea from pistachio orchards are spatially and temporally stable. This stability and uniformity of this population explained why this pathogen does not develop resistance to site-specific fungicides despite the fact that strobilurins have been used for almost 10 years and carboxamide for seven years now with no signs of any resistance, despite the fact that growers apply multiple sprays of these fungicides per season.
Michailides’ accomplishments of research in the science of plant pathology and in his support of the tree fruit and nut crop growers are remarkable and illustrate his devotion to duty and thoughtful innovative approaches to plant disease forecasting and management. After intensive and multifaceted research on the panicle and shoot blight of pistachio caused by Botryosphaeria dothidea, a major disease that became an epidemic in 1995 to 1998 and frightened the pistachio industry, he developed tools for successfully controlling the disease. For this outstanding research, the California pistachio industry awarded him an engraved plaque entitled “Honoring 20 Years of Research Excellence.” Very recently, he has developed and validated two empirical disease warning systems for Botryosphaeria panicle blight of pistachio, which resulted in efficiently reducing the disease even with two to three fewer sprays per season and increasing savings for growers.
Michailides has been doing pioneering research in understanding aflatoxin contamination of pistachio and almond. Based on his group’s in-depth research, Michailides has discovered the reproduction sites of the aflatoxigenic fungi in tree nut and fig orchards, determined how contamination of nuts occurs in the field, and developed techniques to identify and eliminate aflatoxin-contaminated nuts and figs. He has discovered that 99.9% of all the aflatoxins are found in early-split nuts infested with the navel orangeworm. Because of Michailides’ studies, a distinct suture staining of early-split nuts has been identified and is now being adapted by the industry in screening aflatoxin-contaminated pistachio nuts that escape electronic sorting.
Michailides has been an amazingly prolific writer and has published more than 180 refereed articles. He has been very active in The American Phytopathological Society (APS), serving as a member and/or chair of various APS committees. He has also served as associate editor (1991–1993) and senior editor (1995–1997) of Plant Disease and senior editor (2006–2008) of Phytopathology. He has established cooperation with international scientists in more than 10 countries.
