Jonathan has 15 years experience as an avocado researcher in South Africa. Initial interests were postharvest fruit quality, preharvest effects on postharvest quality and growth regulation. Other later research interests were sink source relationships and dominance effects in the flower panicle and the dominance effects between vegetative and reproductive flushing and canopy manipulation. Jonathan emigrated to New Zealand in 1993. More recently his research thrust has been into avocado nutrition using a DRIS based approach. Jonathan is presently the CEO of the New Zealand avocado industry and takes responsibility for the industry research program.


Basic and applied research on the regulation of flowering, fruit set and fruit development of the avocado; development of practical methods for improving avocado production and reducing alternate bearing using fertilization and plant growth regulators.




Piet Stassen is currently the Division Manager for Crop Management at the ARC-ITSC. He has sixteen years experience as a researcher in the deciduous fruit industry, 7 years as University lecturer in Horticulture, and 6 years as Research Manager for Horticulture and Physiology of tropical and subtropical crops. He has specialized in horticulture and plant physiology (tree training and manipulation, rootstocks, light management, energy requirements, nutrient metabolism and allocation physiology). As a researcher in avocados for the last 6 years he as authored or coauthored 25 publications on avocado cultivation and physiology and has given 28 lectures on these subjects.


Nigel Wolstenholme has been involved in avocado research since 1977. His field of interest has been the yield problem, and tree ecophysiology. Manipulation of trees to improve sustainable yield of quality fruit has been the focus of interest. He is one of 3 editors and a contributor to the CABI scientific text on avocado to be published during 2000.