October 30 – November 1, 2003
Session 1. Water Movement and Stress Management
Chair: Alejandro Barrientos Priego, Universidad Autonoma Chapingo, Mexico
Vice-Chair: Ben Faber, UC Cooperative Extension, Ventura County
The overall goals of the Water Movement and Stress Management Session are to briefly discuss factors which influence the movement of water within the avocado tree and how this in turn affects the tree’s ability to respond to environmental stress. Brief presentations will be given on the following topics prior to audience discussion.
Alejandro Barrientos – Germplasm variability and water stress
Benjamin Zur – When and how much to irrigate
David Goldhammer – Soil moisture measuring devices
Francisco Mena – Wetted soil volume and how this influences water stress
Robert Heath – The tree’s response to water stress
Ben Faber – How does slope and aspect affect tree water use?
Session 2. Salinity Management
Chair: Stephen Grattan, University of California, Davis
Vice-Chair: James D. Oster, University of California, Riverside
The overall goals of the Salinity Management Session are 1) to present condensed summaries from a variety of experiments that address various aspects of avocado response to salinity, 2) stimulate good discussion among panel members and the audience and 3) answer to the best detail possible the following questions.
a) Do salinity (osmotic) and specific-ion damage (i.e. chloride and sodium) contribute to avocado’s extreme sensitivity to salinity? If so, which process is more damaging? What influence does reducing the Na/Ca ratio have on tree performance?
b) Can reclaimed waste-water be used for irrigation of avocado? If so, what are the upper limits for EC, Cl, or Na?
c) What irrigation management strategies can be adopted in avocado orchards to optimize their response to irrigation with poor quality water?
d) Is there an integrated approach to salinity management in avocado that can be recommended (i.e. irrigation, amendments, shifting to tolerant rootstocks, etc)?
e) What is the long-term feasibility of shifting to more salt-tolerant rootstocks?
Salinity tolerance of avocado; the role of the rootstock
Mary Lu Arpaia, Mike Mickelbart – Summary of salinity studies examining various avocado rootstocks
Nirit Bernstein – Effect of salinity on avocado root and shoot growth
Miriam Zilberstaine – The influence of avocado rootstocks on the tree resistance to salinity
Feasibility of irrigating avocado with reclaimed waste-water; long term salinity studies
Gary Bender – Use of reclaimed water on avocado in San Diego County; problems and solutions
Joseph Shalhevet – Avocado sensitivity to salinity revisited
Open Discussion (Panelists and Audience)
Irrigation management strategies using saline water
Andreas Neahaus – An integrated approach to irrigation and salinity management
Avraham Meiri – Salinity aspects related to partial soil-surface wetting, Irrigation frequency and leaching timing
Jim Oster – Water, salinity and chloride effects on productivity of Hass avocado
Open discussion (Panelists and Audience)
Session 3. Quality Management
Chair: Peter Hofman, Department of Primary Industries, Queensland, Australia
Vice-Chair: Allan Woolf, HortResearch, New Zealand
We wish to structure the program by focusing on the following questions: are there avocado quality problems at the marketplace; what the causes are; and what recent advances in research and handling will help us these quality problems.
We will have 2 presentations that will discuss the US market dynamics for avocado followed by a series of sessions containing short presentations. Each presentation addressing the stated issue or question will last for no more than 5 minutes. At the end of each of these presentations there will be time for several questions and open discussion.
The avocado market
Jan DeLyser – Where avocados fit into this picture
Jonathan Cutting, Peter Hofman, Reuben Hofshi, Allan Woolf – How to assess quality at the consumer level
Mary Lu Arpaia, Jonathan Cutting, Gawie Eksteen, Peter Hofman – Improving quality to the consumer
Measuring and predicting maturity
Mary Lu Arpaia, Allan Woolf, John Bower – % DM measurement
Mary Lu Arpaia, Reuben Hofshi – Using % DM to predict eating quality
Reducing internal and external damage during cold storage
Peter Hofman, John Bower, Gawie Eksteen, Allan Woolf – Pre-harvest and harvest manipulation
John Bower, Gawie Eksteen – Postharvest treatments
Gawie Eksteen, Jonathan Cutting – What are the NEW future directions for improving outturns
Kerry Everett, Joseph Smilanick – Reducing inoculum load
Peter Hofman, Kerry Everett, Allan Woolf, Joseph Smilanick – Increasing fruit robustness
Peter Hoffman, Kerry Everett, Jonathan Cutting – How to predict rots severity
Peter Hofman, Allan Woolf, Gawie Eksteen – Ethylene
Allan Woolf, Edna Pesis, Julio Retamales – 1-MCP
Summary – Peter Hofman and Allan Woolf
Session 4. Light Management
Chair: Robert Heath, University of California, Riverside
Vice-Chair: Grant Thorp, HortResearch, New Zealand
The goals of the Light Management Session are to present a broad overview of the science behind light management and the practicalities of implementing theory in the orchard. The session is designed to stimulate discussion among panel members and the audience and to evaluate the different light management strategies available to growers.
Robert Heath – Introduction
Grant Thorp – Converting sunlight to fruit
Michael Mickelbart and Robert Heath – Photosynthesis, stomatal conductance etc…. what does it all mean?
Grant Thorp – Pruning systems and planting densities
Francisco Gardiazabal (Chile), Reuben Hofshi (California), Grant Thorp (New Zealand) – Making it all work - Commercialization of light and management strategies: Examples and discussion of experiences throughout the world
Bob Heath and Grant Thorp – Conclusions and wrap up
Bonus Session I
Matan Hadari, Bejamin Zur, Guedi Capluto and Liviu Singer (Technion, Israel Institute of Technology) – A three-dimensional model for the light economy of avocado orchards
One of the most important factors in a dense canopy orchard’s productivity and development is the light regime. Subtropical species, such as the avocado tree tend to fill the gaps in the canopy by vigorous growth. This growth causes shading between the rows, and prevents light from penetrating into the orchard’s canopy during most of the day.
The intercepted radiation over the tree canopy has significant influence over vital processes in tree’s annual cycle, such as pollination, vegetative – reproductive ratios, and fruit yield and quality. A shaded orchard is typically lower in yield, most of which is located at the tree tops, thus making fruit picking harder, and adding additional costs.
The overall objective of the research presented here is to build and field test a comprehensive model for the light economy of an avocado orchard. The resulting model would be used as a tool for the design of future orchard as well as for the development of optimal pruning practices.
The model uses architectural lighting software, “Radiance”, considered to be the most physically accurate software in the market, coupled with an AutoCAD based models to mimic the light regime in a range of avocado orchard geometries. Two approaches for evaluating optimal light management are used: Distribution of total light falling on three heights of the outer envelope of the tree, and a “photosynthetically active volume”- the volume of canopy with sufficient light for photosynthetic activity behind above three heights.
Simulation results are presented and compared with light distribution measurements taken under realistic conditions in avocado orchards at kibbutz Regba in northern Israel. The significance of model predictions is discussed.
Bonus Session II
Edgar Quero Gutiérrez (División de Investigación, Instituto Tecnológico, Uruapan, Michoacán, Mexico) – The flow of carbohydrates in the avocado crop (Persea americana Mill. var. Hass) and its anatomic/nutrition relation
Session 5. Pest Management
Chair: Mark Hoddle, University of California, Riverside
Vice-Chair: Joseph Morse, University of California, Riverside
This panel will focus on a discussion of invasive species and their impact on pest management strategies in California. A series of short presentations will be given introducing this topic and then opened for general discussion.
Mark Hoddle, Joseph Morse – Introduction
Mark Hoddle – New Avocado Pests on the Horizon: Observations from foreign exploration in Mexico
Jorge Peña – Pests threatening avocado: How can their impact be avoided?
Laurence Mound – Invasive thrips as a threat to Californian avocado production
Manes Wysoki – New invasive pests and present status of some previously introduced ones in avocado plantations in Israel
Pascal Oevering – Glassy Winged Sharpshooters (Homalodisca coagulata) in avocado orchards in southern California
Session 6. Nutrient Management
Chair: Nigel Wolstenholme, University of Natal, South Africa
Vice-Chair: Guy Witney, California Avocado Commission
This panel will cover the complexity of avocado nutrition, including current techniques used to assess tree nutritional status, nutrient types and application methods and the effects of tree nutritional status on fruit quality. Speakers will provide an introduction to our current understanding of the topic in industries world-wide; and provide the foundation for a discussion on past experiences and future directions in nutrition.
Nigel Wolstenholme – Introduction: Avocado nutrition problems in different parts of the world, and ecophysiological considerations
Guy Witney – Orchard nutrition management approaches
Are there reliable alternatives to standard leaf and soil analysis: fine-tuning leaf and soil analysis
Nigel Wolstenholme – Nitrogen: the key manipulator element
Carol Lovatt – Foliar feeding: How useful is it, and for what elements?
Emi Lahav – Fertigation: pros and cons
Samuel Salazar Garcia – Fertilization for fruit quality
Ben Faber, Guy Witney – Organic avocado orchards
John Menge – Rootstock effects on nutrition management
Nigel Wolstenholme – The importance of mulching
Nigel Wolstenholme – Concluding comments