Laveran W. (Pete) Timmer
Laveran W. (Pete) Timmer was born in West Olive, MI. He received his B.S. in botany and plant pathology from Michigan State University, and completed studies for his Ph.D. at the University of California, Riverside, in 1969. Midway through his graduate program, in which he worked on the genetics and physiology of Phytophthora capsici and P. drechsleri under professors D. C. Erwin and G. A. Zentmyer, he spent 2 years as a Purdue Fellow in Latin America. His experiences in citrus diseases in Concordia, Argentina, plus development of a fluent command of Spanish, initiated his career in citrus pathology and involvement in fungal, viral, and bacterial diseases affecting citrus throughout North and South America. Dr. Timmer is now considered the leading citrus pathologist in the Americas and is known worldwide for his pathology and citricultural expertise.
Dr. Timmer began his academic career in 1970 as an assistant professor at Texas A&I University, with research, extension, and teaching responsibilities in citrus pathology for the Rio Grande Valley. During his 8-year tenure in Texas, Dr. Timmer made a substantial contribution in the crop loss assessment and management of Phytophthora, nematodes, and fungal diseases of citrus. However, his most far-reaching discovery was the similarities between the ringspot symptoms of grapefruit leaves in Texas and a form of citrus psorosis in Argentina. He demonstrated that the Texas ringspot virus was mechanically transmissible from citrus to citrus as well as to many other herbaceous plants. Further collaboration with S. M. Garnsey, USDA, Orlando, confirmed that mechanically transmitted isolates of ringspot virus caused typical psorosis bark scaling. This finding led to its purification through joint research efforts with K. S. Derrick and proposal of a new group of viruses, the Ophioviruses. Rapid detection techniques are now available for diagnosis in the field and for budwood certification programs. In 1978, Dr. Timmer was recruited as an associate professor of plant pathology to the University of Florida, Citrus Research and Education Center (CREC), at Lake Alfred. In 1983, he was promoted to professor. In Florida he expanded the programs on root health and tree declines he initiated in Texas. He was one of the first to develop methods for evaluation of systemic fungicides for control of Phytophthora foot rot and root rot of citrus. Dr. Timmer identified P. palmivora as a new major species attacking citrus in Florida and established quantitative assay procedures that allowed Phytophthora management by commercial laboratories.
His greatest efforts have been in the studies of the etiology, epidemiology, and control of fungal and bacterial diseases of citrus fruits and foliage. His foremost contribution in foliar diseases of citrus occurred when postbloom fruit drop (PFD) disease caused by Colletotrichum acutatum was discovered in Florida in the mid- 1980s. Dr. Timmer, along with his students, developed an effective program to address this localized but increasingly serious problem to the citrus industries of the Americas. The mechanism of over-seasoning of the PFD was demonstrated, and the disease cycle was defined. A model, developed to predict disease severity, resulted in yield increases up to 500%. It reduced fungicide applications during the bloom period and has been widely adopted by Florida growers. In 1996, Dr. Timmer was awarded the Lee M. Hutchins Award by APS for his series of publications in Phytopathology and Plant Disease on this disease. Through collaborations in Australia and Argentina, he has clarified the etiology of scab diseases and the epidemiology of citrus canker bacterium. He has advised USDA-APHIS on the status of several exotic foliar pathogens as disease threats to U.S. citrus production.
One of the greatest challenges of his career in Florida has been citrus blight, a serious decline disease of unknown etiology believed by many to be a nutritional problem. Although it has baffled citrus pathologists for over 100 years, Dr. Timmer, with colleagues at CREC, helped to characterize citrus blight, and developed useful diagnostic tests. He provided leadership to studies that demonstrated transmissibility of citrus blight by root grats. This focused efforts on graft transmissible, systemic pathogens as causal agents.
As an internationally known expert on citrus diseases, Dr. Timmer has received many invitations to participate in workshops, symposia, and consultations. He is author or co-author on more than 145 journal papers, book chapters, and review articles, as well as numerous technical reports. He has trained several students and colleagues from South America and the Mediterranean. He was an assistant director of CREC from 1991 to 1993. Dr. Timmer was associate and senior editor of Phytopathology from 1992 to 1996. He is the senior editor of and major contributor to the Compendium of Citrus Diseases and the Citrus Health Management Guides, the leading publications on citrus pathology from APS Press. He received the International Organization of Citrus Virologists Special Award for Exceptional Research in 1989 and the Citrus Research and Educational Scientist of the Year Award in 1995. Pete is an avid bird watcher and a member of the Audubon Society. He has identified over 570 species in North America and 2,200 species in his world travels. He always looks forward to extending those lists.
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