Jonathan Gressel

Last updated
Jonathan Ben Gressel
Gressel Edited.jpg
Born(1936-10-30)October 30, 1936 [1]
Cleveland, Ohio [1]
NationalityAmerican
Alma mater University of Wisconsin–Madison
Scientific career
FieldsPlant geneticist, Agricultural science
Institutions Weizmann Institute of Science
External videos
Nuvola apps kaboodle.svg “Pr. Jonathan Gressel, Weizmann Institute of Science (Israel)”

Jonathan Gressel (born October 30, 1936, in Cleveland, Ohio) is an Israeli agricultural scientist and Professor Emeritus at the Weizmann Institute of Science in Rehovot, Israel. [2] Gressel is a "strong proponent of using modern genetic techniques to improve agriculture" especially in third world and developing countries such as Africa. [3] In 2010, Gressel received Israel's highest civilian award, [4] the Israel Prize, for his work in agriculture. [1]

Contents

Early life

Jonathan Ben Gressel were born on October 30, 1936, in Cleveland, Ohio, US, and immigrated to Israel with his family, [2] making aliyah in 1950 at the age of 14. [3]

Education

Gressel completed his secondary education at Pardes Hanna Agricultural High School in Israel in 1955. He returned to the United States, where he earned his B.Sc. in Plant Sciences at Ohio State University. He then attended the University of Wisconsin where he obtained his master's degree in Botany (Plant Physiology) in 1957, working with Folke K. Skoog, and his Ph.D. degree in 1962 working with LeRoy G. Holm, Eldon H. Newcomb, and R. H. Burris. [1]

Career

Gressel joined the Weizmann Institute of Science in Rehovot, Israel, in 1962, working in the biochemistry department. [2] In 1963 he moved to the Plant Genetics Department (later the Department of Plant and Environmental Science.) [1] For a number of years, he held the Gilbert de Botton Chair of Plant Sciences. [5] As of 2005, he became a professor emeritus at the Weizmann Institute. [1]

Gressel has edited several journals, including Plant Science and others in this field. He has taught classes on transgenic biosafety for the United Nations Industrial Development Organization (UNIDO). [2]

Gressel belongs to the American Society of Plant Biologists, the International Weed Science Society, and Sigma Xi. He is an Honorary member of the Weed Science Society of America. He served as president of the International Weed Science Society from 1997 to 1999. [1]

In 2008 Jonathan Gressel co-founded the company TransAlgae. [6]

Research

Two-thirds of the food eaten by the human population comes from just four main plant species: wheat, rice, maize, and soybeans. [7] Historically, reliance on genetically uniform crops has put the human population at risk for catastrophic crop failures such as the European Potato Failure and the Great Famine of Ireland. [8] Throughout the twentieth century, plant breeding has focused on increasing agricultural productivity, while pesticides and herbicides have been widely used to increase yields. Concerns have arisen about reliance on chemical means of weed control, and the ability of pests and weeds to develop resistance to pesticides and herbicides. [9]

Jonathan Gressel and Lee Segel developed the first simulation model for the development of resistance to herbicides, later modifying and expanding it. Their models have been widely used to predict and study the possible evolution of herbicide resistance. [10] [11] [12] In 1982, Gressel and Homer LeBaron edited the first book to be published on Herbicide Resistance in Plants. [1]

Gressel and Segel's earliest models are relatively simple, and tend to predict pessimistic outcomes for the evolution and management of resistance. Their later models are more complex and suggest a variety of options for managing herbicide resistance. [13] [10] [11] [12] In 1991, Gressel reported a number of characteristics that tend to be associated with plants that develop herbicide resistance: 1) Herbaceous annuals 2) Self-fertile 3) Found in agricultural habitats 4) Colonisers 5) High reproductive capacity 6) Complex genetic variability (polymorphic phenotypes) [9] [14]

Assuming that a heritable variation of a trait occurs in a population, the rate at which it evolves will depend on the mode of inheritance of the traits, and intensity of selection in the population. The rate at which naturally resistant individuals occur in a population varies with plant species. Persistent applications of herbicides can result in recurrent selection, resulting in a shift in the average fitness in the population due to herbicide exposure. Resistant individuals in a population will produce seed for the next generation, while non-resistant individuals do not live to do so. Selection pressure will drive the proportion of resistant individuals in the next generation upward. The rate at which herbicide resistance appears in a weed population will depend on factors such as the initial frequency of resistant individuals, how many individuals in a population are treated, the mode of inheritance of the gene or genes involved, and the nature and extent of herbicide use. [9] [15]

Gressel has extensively studied weed control practices, with particular attention to developing countries where farmers may not have the resources to buy and use expensive herbicides. [15] [12] Herbicide rotation is one type of management practice that may slow the evolution of herbicide-resistant plants. [13] [10] [11] [12] In Molecular biology of weed control (2002) Gressel also reviews possible approaches such as the development of plant species that can produce their own weed-killing allelochemicals and the development of insects and plant pathogens that can act as biological control agents by targeting herbicide-resistant weeds. [16]

In recent years, Gressel has focused on control options for the root parasitic weeds Orobanche (broomrape) [17] and Striga (witchweed). [18] [19] These weeds are particularly important in the Middle East and sub-Saharan Africa, where they can cause farmers to lose half their potential yield and cause long-term environmental damage. Gressel has developed herbicide-resistant maize seeds coated in pesticide, which are now commercially available in Kenya and Uganda. [20] [21] [22]

Gressel is also known for inventing the biobarcode. He has proposed the creation of a universal public repository to track ‘biobarcoded’ biological materials. PCR (polymerase chain reaction) based techniques would be used to create, assign and identify nucleotide sequences that can be recognized by universal primers. There are a variety of reasons to use biobarcodes, including protection of patented organisms, detection of transgenics, and tracking of the dispersal of genetic materials. Gressel suggests that such a system would have benefits to industry, regulators and taxpayers. [23] [24]

Another area of Gressels's research concerns the evolution of volunteers (plants that germinate in later years, after a crop has been harvested) and feral plants (derived from crops that have become de-domesticated). Understanding processes in the domestication and de-domestication of crops is particularly important as scientists develop and commercialize transgenic crops. In 2005, Gressel edited Crop ferality and volunteerism, the first book published on the topic. [25] [26]

In 2008, Gressel published Genetic Glass Ceilings: Transgenics for Crop Biodiversity, a careful, detailed, and passionate examination of the possible application of plant sciences such as molecular biology and transgenics to worldwide agricultural policies. He discusses the limitations and possible genetic modification of fourteen underutilised crops. He describes ways in which plant sciences could be used to expand biodiversity, address agricultural problems, and protect the environment. [27]

"While these crop-specific chapters abundantly display Gressel's vast knowledge of genetics, molecular biology, agronomy, and plant breeding, his approach engages the reader with the style of a mystery novel. Each presents a set of genetic puzzles, or surprising and unexpected molecular events, which in the end are deftly resolved with an insight worthy of Sherlock Holmes. Although his chapters are dense with scientific knowledge and the scientific method, they are nonetheless riveting for those who can feel the excitement of scientific exploration and the joy of discovery." [27]

In 2008 Jonathan Gressel co-founded TransAlgae, with his son, Noam Gressel and others. His goal was to develop genetically modified algae for growth in customized indoor and outdoor reactors that would be resistant to colonization and take-over by other types of algae and bacteria. The genetically designed algae, along with its optimal medium and growing system, could be specialized for a particular partner. To address limitations in water availability, the systems are designed to work with either fresh water or sea water. In the event of an accidental release, the algae were designed to die within a few hours, to prevent their escape into the wild. [6] Possible applications of specialized algae include feedstocks for biofuels, [28] [29] animal feed, [30] and drug delivery. [31] Gressel has applied for or received at least 21 patents. [1]

Awards

Publications

Gressel has published more than 300 peer reviewed journal articles and book chapters, and eight books. His Herbicide resistance in plants (1982) [1] and Crop ferality and volunteerism (2005) are the first books on those topics. [25]

Books

Papers

Related Research Articles

<i>Eleusine coracana</i> Species of grass

Eleusine coracana, or finger millet is an annual herbaceous plant widely grown as a cereal crop in the arid and semiarid areas in Africa and Asia. It is a tetraploid and self-pollinating species probably evolved from its wild relative Eleusine africana.

<span class="mw-page-title-main">Herbicide</span> Type of chemical used to kill unwanted plants

Herbicides, also commonly known as weed killers, are substances used to control undesired plants, also known as weeds. Selective herbicides control specific weed species while leaving the desired crop relatively unharmed, while non-selective herbicides (sometimes called total weed killers kill plants indiscriminately. Due to herbicide resistance – a major concern in agriculture – a number of products combine herbicides with different means of action. Integrated pest management may use herbicides alongside other pest control methods.

Agricultural biotechnology, also known as agritech, is an area of agricultural science involving the use of scientific tools and techniques, including genetic engineering, molecular markers, molecular diagnostics, vaccines, and tissue culture, to modify living organisms: plants, animals, and microorganisms. Crop biotechnology is one aspect of agricultural biotechnology which has been greatly developed upon in recent times. Desired trait are exported from a particular species of Crop to an entirely different species. These transgene crops possess desirable characteristics in terms of flavor, color of flowers, growth rate, size of harvested products and resistance to diseases and pests.

<span class="mw-page-title-main">Genetically modified food</span> Foods produced from organisms that have had changes introduced into their DNA

Genetically modified foods, also known as genetically engineered foods, or bioengineered foods are foods produced from organisms that have had changes introduced into their DNA using various methods of genetic engineering. Genetic engineering techniques allow for the introduction of new traits as well as greater control over traits when compared to previous methods, such as selective breeding and mutation breeding.

<span class="mw-page-title-main">Pesticide resistance</span> Decreased effectiveness of a pesticide on a pest

Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens survive and pass on their acquired heritable changes traits to their offspring. If a pest has resistance then that will reduce the pesticide's efficacy – efficacy and resistance are inversely related.

<span class="mw-page-title-main">Weed control</span> Botanical component of pest control for plants

Weed control is a type of pest control, which attempts to stop or reduce growth of weeds, especially noxious weeds, with the aim of reducing their competition with desired flora and fauna including domesticated plants and livestock, and in natural settings preventing non native species competing with native species.

<span class="mw-page-title-main">Glyphosate</span> Systemic herbicide and crop desiccant

Glyphosate is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSP). It is used to kill weeds, especially annual broadleaf weeds and grasses that compete with crops. Its herbicidal effectiveness was discovered by Monsanto chemist John E. Franz in 1970. Monsanto brought it to market for agricultural use in 1974 under the trade name Roundup. Monsanto's last commercially relevant United States patent expired in 2000.

<span class="mw-page-title-main">Genetically modified crops</span> Plants used in agriculture

Genetically modified crops are plants used in agriculture, the DNA of which has been modified using genetic engineering methods. Plant genomes can be engineered by physical methods or by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors. In most cases, the aim is to introduce a new trait to the plant which does not occur naturally in the species. Examples in food crops include resistance to certain pests, diseases, environmental conditions, reduction of spoilage, resistance to chemical treatments, or improving the nutrient profile of the crop. Examples in non-food crops include production of pharmaceutical agents, biofuels, and other industrially useful goods, as well as for bioremediation.

<i>Striga</i> Genus of flowering plants belonging to the broomrape family

Striga, commonly known as witchweed, is a genus of parasitic plants that occur naturally in parts of Africa, Asia, and Australia. It is currently classified in the family Orobanchaceae, although older classifications place it in the Scrophulariaceae. Some species are serious pathogens of cereal crops, with the greatest effects being in savanna agriculture in Africa. It also causes considerable crop losses in other regions, including other tropical and subtropical crops in its native range and in the Americas. The generic name derives from Latin strī̆ga, "witch".

<span class="mw-page-title-main">Phenoxy herbicide</span> Class of herbicide

Phenoxy herbicides are two families of chemicals that have been developed as commercially important herbicides, widely used in agriculture. They share the part structure of phenoxyacetic acid.

<span class="mw-page-title-main">Genetically modified plant</span> Plants with human-introduced genes from other organisms

Genetically modified plants have been engineered for scientific research, to create new colours in plants, deliver vaccines, and to create enhanced crops. Plant genomes can be engineered by physical methods or by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors. Many plant cells are pluripotent, meaning that a single cell from a mature plant can be harvested and then under the right conditions form a new plant. This ability is most often taken advantage by genetic engineers through selecting cells that can successfully be transformed into an adult plant which can then be grown into multiple new plants containing transgene in every cell through a process known as tissue culture.

<span class="mw-page-title-main">Weed</span> Plant considered undesirable in a particular place or situation

A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals. Plants with characteristics that make them hazardous, aesthetically unappealing, difficult to control in managed environments, or otherwise unwanted in farm land, orchards, gardens, lawns, parks, recreational spaces, residential and industrial areas, may all be considered weeds. The concept of weeds is particularly significant in agriculture, where the presence of weeds in fields used to grow crops may cause major losses in yields. Invasive species, plants introduced to an environment where their presence negatively impacts the overall functioning and biodiversity of the ecosystem, may also sometimes be considered weeds.

<span class="mw-page-title-main">SmartStax</span> Seeds protected against bugs, weeds

SmartStax is a brand of genetically modified seed made through a collaboration between Monsanto Company and Dow Chemical Company. It takes advantage of multiple modes of insect protection and herbicide tolerance. SmartStax takes advantage of Yieldgard VT Triple (Monsanto), Herculex Xtra (Dow), RoundUp Ready 2 (Monsanto), and Liberty Link (Dow). The traits included protect against above-ground insects, below-ground insects, and provide broad herbicide tolerance. It is currently available for corn, but cotton, soybean, and specialty crop variations are to be released. Previously, the most genes artificially added to a single plant was three, but Smartstax includes eight. Smartstax also incorporates Monsanto's Acceleron Seed Treatment System which protects against insects at the earliest stages of development. Smartstax is sold under the Genuity (Monsanto) and Mycogen (Dow) brands.

<span class="mw-page-title-main">Genetically modified rice</span>

Genetically modified rice are rice strains that have been genetically modified. Rice plants have been modified to increase micronutrients such as vitamin A, accelerate photosynthesis, tolerate herbicides, resist pests, increase grain size, generate nutrients, flavors or produce human proteins.

<i>Striga hermonthica</i> Species of flowering plant

Striga hermonthica, commonly known as purple witchweed or giant witchweed, is a hemiparasitic plant that belongs to the family Orobanchaceae. It is devastating to major crops such as sorghum and rice. In sub-Saharan Africa, apart from sorghum and rice, it also infests maize, pearl millet, and sugar cane.

4-Hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors are a class of herbicides that prevent growth in plants by blocking 4-Hydroxyphenylpyruvate dioxygenase, an enzyme in plants that breaks down the amino acid tyrosine into molecules that are then used by plants to create other molecules that plants need. This process of breakdown, or catabolism, and making new molecules from the results, or biosynthesis, is something all living things do. HPPD inhibitors were first brought to market in 1980, although their mechanism of action was not understood until the late 1990s. They were originally used primarily in Japan in rice production, but since the late 1990s have been used in Europe and North America for corn, soybeans, and cereals, and since the 2000s have become more important as weeds have become resistant to glyphosate and other herbicides. Genetically modified crops are under development that include resistance to HPPD inhibitors. There is a pharmaceutical drug on the market, nitisinone, that was originally under development as an herbicide as a member of this class, and is used to treat an orphan disease, type I tyrosinemia.

<span class="mw-page-title-main">DMH-11 Mustard</span> Genetically modified variety of mustard plant

Dhara Mustard Hybrid-11, otherwise known as DMH - 11, is a genetically modified hybrid variety of the mustard species Brassica juncea. It was developed by Professor Deepak Pental from the University of Delhi, with the aim of reducing India's demand for edible oil imports. DMH - 11 was created through transgenic technology, primarily involving the Bar, Barnase and Barstar gene system. The Barnase gene confers male sterility, while the Barstar gene restores DMH - 11's ability to produce fertile seeds. The insertion of the third gene Bar, enables DMH - 11 to produce phosphinothricin-N- acetyl-transferase, the enzyme responsible for Glufosinate resistance. This hybrid mustard variety has come under intense public scrutiny, mainly due to concerns regarding DMH - 11's potential to adversely affect the environment as well as consumer health. DMH - 11 was found not to pose any food allergy risks, and has demonstrated increased yields over existing mustard varieties. Conflicting details and results regarding the field trials and safety evaluations conducted on DMH - 11 have delayed its approval for commercial cropping.

Steven Runo is a Kenyan researcher who is a professor at Kenyatta University. Runo has extensively studied the pathogens of African cereal crops, including Striga. He was awarded the 2020 Royal Society Africa Prize.

<span class="mw-page-title-main">Indaziflam</span> Preemergent herbicide discovered in 2009

Indaziflam is a preemergent herbicide especially for grass control in tree and bush crops.

<span class="mw-page-title-main">Chlorsulfuron</span> ALS inhibitor herbicide

Chlorsulfuron is an ALS inhibitor herbicide, and is a sulfonylurea compound. It was discovered by George Levitt in February 1976 while working at DuPont, which was the patent assignee.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 "10 JONATHAN GRESSEL – an illustrious weed scientist" (PDF). IWSS Newsletter. International Weed science Society. September 2011. p. 10. Retrieved 2 July 2018.
  2. 1 2 3 4 Cohn, Robert A. (July 2, 2015). "Weizmann Professor Finds Merit in Papal Document on Climate Change". St. Louis Jewish Light. Retrieved 1 July 2018.
  3. 1 2 Meyers, Nechemia (October 4, 2002). "Israeli scientists create 'designer plants'". Cleveland Jewish News. Retrieved 2 July 2018.
  4. ↑ Litas, Lee A. (July 31, 2015). "Weizmann expert speaks on climate change". Chicago Tribune. Retrieved 3 July 2018.
  5. ↑ "Weizmann Professorial Chairs, CDCs and Fellowships". Weizmann Institute of Science. 2004. Retrieved 6 July 2018.
  6. 1 2 Kloosterman, Karin (May 16, 2010). "Seeding a green need for feed". Israel21C. Retrieved 2 July 2018.
  7. ↑ Kromdijk, Johannes; Long, Stephen P. (9 March 2016). "One crop breeding cycle from starvation? How engineering crop photosynthesis for rising CO and temperature could be one important route to alleviation". Proceedings of the Royal Society B: Biological Sciences. 283 (1826): 20152578. doi:10.1098/rspb.2015.2578. PMC   4810849 . PMID   26962136.
  8. ↑ Briggs, Helen (21 May 2013). "Irish potato famine pathogen identified". BBC News. Retrieved 7 July 2018.
  9. 1 2 3 Pieterse, P.J. (January 2010). "Herbicide resistance in weeds – a threat to effective chemical weed control in South Africa". South African Journal of Plant and Soil. 27 (1): 66–73. doi: 10.1080/02571862.2010.10639971 . S2CID   86481191.
  10. 1 2 3 Roush, Mary Lynn; Radosevich, Steven R.; Maxwell, Bruce D. (1990). "Future Outlook for Herbicide-Resistance Research". Weed Technology. 4 (1): 208–214. doi:10.1017/S0890037X00025239. JSTOR   3986870. S2CID   82644597.
  11. 1 2 3 Gressel, Jonathan; Segel, Lee A. (March 1990). "Modelling the Effectiveness of Herbicide Rotations and Mixtures as Strategies to Delay or Preclude Resistance". Weed Technology. 4: 186–198. doi:10.1017/S0890037X00025215. S2CID   80799355.
  12. 1 2 3 4 Gressel, Jonathan (November 2009). "Evolving understanding of the evolution of herbicide resistance". Pest Management Science. 65 (11): 1164–1173. doi:10.1002/ps.1842. PMID   19743401.
  13. 1 2 Labrada, R. (2003). Weed management for developing countries. Rome: Food and Agriculture Organization of the United Nations. pp. 197–204. ISBN   978-9251050194 . Retrieved 7 July 2018.
  14. ↑ Gressel, J. (1991). "Why get resistance if it can be prevented or delayed". In Caselay, J.C.; Cussans, G.W.; Atkin, R.K. (eds.). Herbicide Resistance in Weeds and Crops. Oxford: Butterworth, Heinemann.
  15. 1 2 Gressel, Jonathan (2002). Molecular biology of weed control. London [u.a.]: Taylor & Francis. ISBN   978-0415266420.
  16. ↑ Tranel, Patrick J.; Horvath, David P. (March 2009). "Molecular Biology and Genomics: New Tools for Weed Science". BioScience. 59 (3): 207–215. doi:10.1525/bio.2009.59.3.5. S2CID   85814418 . Retrieved 7 July 2018.
  17. ↑ Fernández-Aparicio, Mónica; Reboud, Xavier; Gibot-Leclerc, Stephanie (19 February 2016). "Broomrape Weeds. Underground Mechanisms of Parasitism and Associated Strategies for their Control: A Review". Frontiers in Plant Science. 7: 135. doi: 10.3389/fpls.2016.00135 . PMC   4759268 . PMID   26925071.
  18. ↑ Rodenburg, Jonne; Demont, Matty (2009). "Potential of Herbicide-Resistant Rice Technologies for Sub-Saharan Africa". Ag Bio Forum. 12 (3 & 4): 313–325. Retrieved 3 July 2018.
  19. ↑ Gressel, Jonathan (May 2009). "Crops with target-site herbicide resistance for Orobanche and Striga control". Pest Management Science. 65 (5): 560–565. doi:10.1002/ps.1738. PMID   19280593.
  20. ↑ "Strategies to stop Striga". New Agriculturist. No. January. 2004. Retrieved 8 July 2018.
  21. ↑ "Planting Knowledge Green Research at the Weizmann Institute of Science" (PDF). Weizmann Institute of Science. Retrieved 8 July 2018.
  22. ↑ Kanampiu, Fred; Friesen, D.; Gressel, J. (2002). "CIMMYT unveils herbicide-coated maize seed technology for Striga control". Haustorium. 42: 1–3.
  23. ↑ Philipkoski, Kristen (December 13, 2002). "Waiter, There's DNA in My Food". Wired. Retrieved 3 July 2018.
  24. ↑ Gressel, Jonathan; Ehrlich, Gal (December 2002). "Universal inheritable barcodes for identifying organisms". Trends in Plant Science. 7 (12): 542–544. doi:10.1016/S1360-1385(02)02364-6. PMID   12475495 . Retrieved 3 July 2018.
  25. 1 2 Davey, J. (1 January 2007). "Crop Ferality and Volunteerism". Annals of Botany. 99 (1): 205–206. doi:10.1093/aob/mcl244. PMC   2802985 .
  26. ↑ Gressel, Jonathan, ed. (2005). Crop ferality and volunteerism : [Workshop on "Crop Ferality and Volunteerism: a Threat to Food Security in the Transgenic Era?" ... in Bellagio, Italy on May 24 - 28, 2004]. Boca Raton, Fla. [u.a.]: Taylor & Francis. ISBN   978-0-8493-2895-4.
  27. 1 2 Kershen, Drew L (October 2008). "Genetic Glass Ceilings: Transgenics for Crop Biodiversity". Journal of Commercial Biotechnology. 14 (4): 369–370. doi:10.1057/jcb.2008.28. S2CID   154383467.
  28. ↑ "Collaboration formed to develop fuels from algae oil" (PDF). American Recycler. No. January. 2010. p. A6. Retrieved 2 July 2018.
  29. ↑ Maron, Dina Fine (July 22, 2010). "The Race to Make Fuel Out of Algae Poses Risks as Well as Benefits". The New York Times. Retrieved 2 July 2018.
  30. ↑ "Agronomy & Horticulture Seminar - Jonathan Gressel". University of Nebraska–Lincoln. Retrieved 3 July 2018.
  31. ↑ Charoonnart, Patai; Purton, Saul; Saksmerprome, Vanvimon (12 April 2018). "Applications of Microalgal Biotechnology for Disease Control in Aquaculture". Biology. 7 (2): 24. doi: 10.3390/biology7020024 . PMC   6022871 . PMID   29649182.
  32. ↑ "Prof. John Gressel Wins Israel Prize for Agriculture". Arutz Sheva Israel National News. March 2, 2010. Retrieved 7 July 2018.
  33. ↑ "SIGMA XI MEMBERS IN THE NEWS". Sigma Xi Emeritus & Life Member Newsletter. February 2010. Retrieved 2 July 2018.
  34. ↑ "Awards & Fellowships". International Weed Science Society. Retrieved 7 July 2018.
  35. ↑ "WEED SCIENCE SOCIETY OF AMERICA AWARDS" (PDF). WEED SCIENCE SOCIETY OF AMERICA. 2016. Retrieved 2 July 2018.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.