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During my position as sylvicultural research forester I was mentored by a retired forest pathologist (Dr C S Moses) from Wisconsin, USA, who was employed on a contract basis by the Dept. of Forestry.
In 1968 I commenced extramural undergraduate studies at the University of Pretoria, to major in plant pathology. My professor and mentor during my plant pathology undergraduate, graduate and post graduate studies was Prof. J M Kotze, world renowned for his expertise in the control of citrus black spot and foliar and fruit diseases in avocado and mango. Following my graduation in MSc.(Agric.) I was offered a position as Associate Professor in plant pathology at the University of Pretoria, to teach mycology, nematology, plant virology and general plant pathology.
I joined Outspan International (Capespan International) as their citrus research plant pathologist, encumbered with research into the control of citrus black spot, Alternaria, soilborne diseases, citrus nematode, citrus tristeza virus (CTV), citrus greening (HLB), citrus viroid diseases and citrus blight. During my position as citrus research pathologist with Outspan International I was invited by the University of Florida to collaborate with citrus researchers ( Drs. R F Lee, R H Brlansky and K S Derrick) at CREC, Lake Alfred, Florida, on projects related to citrus tristeza virus, citrus blight and citrus greening. The first two sabbaticals (1986 and 1994) extended for periods of 6 months, the third sabbatical (1997) endured for 12 months. It was during my sabbatical in 1997 that I developed single aphid transmitted strains of CTV for use in mild strain cross protection of citrus cultivars in South Africa. All citrus cultivars in South Africa are now pre-immunized with these mild strains and others selected locally in the field.
During 1989 I was invited by Morse Chemicals (now KeyPlex) to conduct efficacy trials with a product named ByPass (now known as KeyPlex 1200 DP) for management of citrus blight. This research was conducted with the collaboration of Drs R F Lee and R H Brlansky of CREC, Lake Alfred, FL and Frank Myers of Myer Consulting, Frostproof, FL. ByPass product was subsequently imported to South Africa for inclusion in citrus blight management field trials.
I resigned from Capespan International in 1999 to join the Dept. of Plant Pathology at UC Riverside, CA, as extension specialist in citrus and avocado. I worked closely with Drs John Menge, Neil O’Connell, Craig Kallsen and Chet Roistacher in solving issues related to Fukumoto and Earli Beck navel scion/rootstock incompatibility.
My career in the USA agricultural industry commenced in 2003 when I joined Improcrop USA (now Alltech CropScience of Lexington, KY) as a sales consultant to CA and FL. I introduced several products especially CropSet, ISR 2000 and Agromos into the citrus and avocado industries of FL and CA. These products are biostimulants and SAR inducers. During my position with Improcop USA I attended conferences in Brazil, South Africa, Turkey and Australia to present field results using these products.
In 2008 I was approached by Monterey AgResources , Fresno (now Brandt-Monterey), to act as R&D Manager. I was encumbered with conducting efficacy trials on herbicides (organic and inorganic), spray adjuvants, fungicides (organic and inorganic), nematicides (organic and inorganic), foliar nutrients and sunburn protectants. Crops worked with were pomegranate, grapes, citrus, cherry and apples. Cherry rain-cracking, color and firmness improvement trials were conducted in collaboration with researchers from WSU, Yakima (Dr Ines Hanrahan) and UC Davis (Dr Kitren Glozer). Apple quality improvement and postharvest disease control in apples and apple replant disease control trials were conducted in collaboration with researchers from WSU in Yakima and Wenatchee ( Dr. Tim Smith). Collaborative research was conducted in postharvest disease control in citrus and grapes with Dr Joe Smilanick of USDA, Parlier, CA and currently with researchers from South Africa at the University of Pretoria (Prof. Lise Korsten) and Tswhane University of Technology, Pretoria (Prof. Dharini Sivakumar). I was instrumental in the registration of Quillaja saponaria as an organic nematicide (Nema-Q from Desertking Int., San Diego, CA) and approval of aqueous potassium silicate (Silmatrix, PQ Corp) by NOB for use as an insecticide/miticide/fungicide under organic production. I conducted field trials with potassium silicate and demonstrated that it could be used to manage dry root rot in citrus, for which there is currently no product registered. These results were presented at the International Citrus Congress in Spain held in November of 2012.
During 2011 I was approached by Gillespie Ag Service, Porterville, CA to join their newly acquired citrus agricultural chemical company Leffingwell Ag Sales, Lindsay, CA as R&D manager, plant pathologist/agronomist. I was encumbered with efficacy testing of nutrients, biostimulants, adjuvants, nematicides, fungicides, irrigation aids, sunburn protection products, miticides, soil compaction remediation and prevention products and transpiration reducing aids e.g. Surround, Vaporgard, Parka, Purshade and Provoscape. Crops worked on included walnuts, almonds, citrus and alfalfa. Furthermore my responsibilities included making presentations at citrus grower meetings on citrus fertilization, pruning of citrus, soilborne disease control, citrus nematode control and use of irrigation aids to enhance water penetration in heavy and compacted soils. Trials were conducted in which urease inhibitors were tested for efficacy in reducing nitrate N leaching in soils. Collaborative trials were conducted with Dr Joe Smilanick of USDA, Parlier, CA, using products to induce color enhancement in grapes and citrus. These results led to the formulation of a color enhancing product for use in citrus named Color Up. Several seaweed extracts from South Africa, Canada and Ireland, were tested for citrus nematode control with comparable results to industry standard nematicides currently used.
I retired from Leffingwell Ag Sales and Gillespie Ag Service in October 2014 to establish a private consulting practice.
Diploma in Forestry, Saasveld College for Foresters, George, South Africa
BSc. (Agric.) Plant Pathology, University of Pretoria, Pretoria, South Africa
MSc.(Agric) Forest Pathology (Thesis: Mycorrhizal Effects on Pinus patula Schlecht.& Cham. in South Africa), University of Pretoria
DSc. (Agric.) Plant Pathology ( Thesis: Aspects of the Tristeza Virus Complex in South Africa), University of Pretoria
1964-1968 - Sylvicultural Research Forester, Dept. of Forestry, Pretoria, South Africa
1969-1973 - Forest Pathologist, Dept. of Forestry, Pretoria, South Africa
1974-1981 - Associate Professor, Dept. Plant Pathology, University of Pretoria, South Africa
1982- 1999 - Citrus Research Pathologist, Capespan International (formerly Outspan International), Nelspruit, South Africa
1999 - 2003 - Extension Specialist Citrus & Avocado, Dept. Plant Pathology, UC Riverside, CA
2003 - 2008 - Sales Consultant, Alltech CropScience (formerly Improcrop), Visalia, CA
2008-2011 - R & D Manager, Brandt-Monterey (formerly Monterey AgResources), Fresno, CA
2011-2014 - R& D Manager/Agronomist, Leffingwell Ag Sales & Gillespie Ag Service, Lindsay and Porterville, CA
2015 - Private consultant, Citrus Pathology & Citrus Nutrition/Arborist
Scientific Society Affiliations
American Phytopathology Society (APS)
International Organization of Citrus Virologists (IOCV)
International Society of Horticultural Science (ISHS)
Society of Nematologists (SON)
Soilborne Plant Pathogen Study Group
Member of Research Gate