Morris R. Bonde was born in Presque Isle, Maine. In 1967, he earned his bachelor’s degree in botany from the University of Maine, where he received the Outstanding Senior Award for the discovery of a new plant-pathogenic Streptomyces sp. that caused acid scab on potatoes. Bonde received an M.S. degree in plant pathology in 1969 from Cornell University. He served in the U.S. Army as an agronomy assistant in the Plant Pathology Division, Crops Directorate, Ft. Detrick, Maryland, from 1969 to 1971. He resumed his graduate education at Cornell University and received his Ph.D. degree in plant pathology in 1974 under the direction of Roy Millar. In 1974, he joined the USDA ARS’s Foreign Disease-Weed Science Research Unit (formerly the Plant Disease Research Laboratory) at Ft. Detrick, where he has maintained an active research program for 40 years studying the biology and epidemiology of exotic fungal plant pathogens that threaten U.S. agriculture. Some of the more prominent diseases that Bonde has studied include downy mildews of corn and sorghum, Karnal bunt of wheat, soybean rust, and chrysanthemum white rust.
Bonde determined important environmental criteria required for the development of several downy mildew diseases of maize, sorghum, and sugarcane. He is a world authority on downy mildew diseases of graminaceous crops and has helped solve major disease problems. Bonde determined the environmental requirements for diseases caused by several pathogens, including Peronosclerospora sorghi, causal agent of sorghum downy mildew of maize and sorghum, and cooperated internationally with recognized downy mildew experts to test the world downy mildew-resistant maize nursery to several species of Peronosclerospora (ultimately greatly reducing the significance of the disease). In 1993, Bonde used his knowledge to help convince Colombia to reverse an embargo of U.S. corn caused by the presence of sorghum downy mildew in the United States. The U.S.–Colombian negotiations resulted in reopening the export market for U.S. corn to Colombia, valued at $129 million per year (5-year average 1994–1998).
Bonde anticipated that Karnal bunt (KB) of wheat could eventually spread to the United States and took the initiative to develop the first KB research program in the United States in 1982. Bonde and his colleague Gary Peterson developed crucial identification and detection techniques that allowed the United States to conduct state and national KB field surveys following the discovery of KB in the United States in 1996. Their method of size-selective-sieving was used to certify that U.S. wheat was free of the KB pathogen, freeing up approximately $5.5 billion annually in U.S. wheat exports. Bonde also developed a novel technique of using acidic electrolyzed water (AEW), generated by electrolysis of a weak sodium chloride solution, for surface-sterilizing KB teliospores and stimulating germination, while eliminating almost all other microorganisms found in wheat samples in KB surveys. With the treatment of either soil or harvested wheat, detection of the pathogen at extremely low numbers was made possible using these techniques.
Bonde initiated research on soybean rust long before Phakopsora pachyrhizi was discovered in the continental United States. He conducted morphological and isozyme comparisons among isolates of soybean rust pathogens from Asia, Australia, Puerto Rico, and Brazil. When rust was discovered in 1994 on soybeans in Hawaii, he demonstrated that soybean rust is caused by at least two species of Phakopsora that are essentially indistinguishable by examination of their uredinial stages. Using isozyme analysis, Bonde showed that the soybean rust pathogen in Hawaii was P. pachyrhizi, the more virulent of the two Phakopsora species. Bonde also examined the host range of P. pachyrhizi and revealed the importance of selected non-soybean leguminous crops and legume weeds in overwintering of P. pachyrhizi. He determined that biotypes of kudzu exist in the United States that vary from highly susceptible to immune and that races of P. pachyrhizi could be differentiated on kudzu. These results indicated that kudzu has the potential for allowing P. pachyrhizi to overwinter in areas where leaves do not freeze during winters, such as Florida and Texas. Bonde initiated in-depth research to determine the effects of environment on the development of soybean rust with the goal of improving soybean rust disease models. He showed that P. pachyrhizi is sensitive to heat, even for brief (e.g., 1-hr) periods, which commonly occur as “extreme” diurnal temperature highs during summer months. These results explain why soybean rust does not increase in intensity until the cooler, fall months.
In response to an outbreak of chrysanthemum white rust (CWR) in California, Washington, and Oregon in 1991–1992, and at the request of APHIS and the California Department of Food and Agriculture, Bonde developed a method to treat cuttings of chrysanthemum with the systemic fungicide myclobutanil, which allowed extremely valuable germplasm to be imported into the United States without importing the pathogen. Bonde and coworkers demonstrated that dipping chrysanthemum cuttings into a solution of myclobutanil (100 mg/L) had extremely high curative effects and prevented movement of Puccinia horiana, the causal agent of CWR, into disease-free areas and facilities. As a result, myclobutanil was registered and recommended by APHIS to control CWR. Recently, Bonde and coworkers showed that spores of Puccinia horiana were not capable of surviving through northeastern U.S. winters. By simulating winter conditions within temperature-controlled growth chambers and using light microscopy and scanning and transmission electron microscopy, they found that Puccinia horiana could systemically infect chrysanthemum plants. These results indicate a possible means for Puccinia horiana to survive through winters in the northeastern United States.
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