Keynote Speakers



Thierry Améglio (INRAE PIAF, Clermont-Ferrand, France) is a senior scientist of the AgroEcoSystem Department at INRAE (French National Research Institute for Agriculture, Food and Environment). He is an ecophysiologist focusing on water relation and winter biology of trees, urban forestry and smart cities, and on biosensors for tree growth and tree vitality. He has published more than 120 papers in peer-reviewed journals and produced 2 licences to knowledge (Xyl’em: a device for measuring the rate of gas embolism in tree branches and petioles. e-PepiPIAF: a wireless, autonomous and connected system for monitoring and assessing the growth and vitality of trees (resistance to drought and frost, etc.) which measures, memorizes and remotely transmits micro-variations in organ diameter (sensitivity below the micron) and air temperature to the point of measurement, without disrupting its operation

Most of these papers on water functioning and winter biology have focused on walnut tree.



Tuesday June 13, in the afternoon (14:50 – 15:35)

Ecophysiological functioning of walnut and main risks in a changing climate

Thierry AMEGLIO and Guillaume CHARRIER

Drought and frost stresses are the most important limiting factors that determine the ecological distribution and production of tree species.

Walnut, in particular, has a low resistance to edaphic drought and frost, which explains its development in lowland areas with deep and fertile soils and its low development at high elevation in our climates.

The ecophysiological tools developed in the laboratory (determination of hydraulic conductance, carbon reserve, water potential, electrolyte leakage and continuous monitoring of trunk or branch diameter variations) allow us to evaluate the risks of drought or frost death throughout the tree’s development cycle and to understand the periods of greatest sensitivity to these risks.

The construction of mechanistic models, based on physiological parameters that vary according to climatic data, makes it possible to predict these risks in future climates and to propose risk maps according to these constraints.

Catherine BAROS


Catherine Baros is responsible for consumer studies at CTIFL. Combining expertise in marketing, sociology and economics, she is specialized in food consumption analysis. In CTIFL, she carries out qualitative and quantitative studies on fruit and vegetable purchase and consumption among French consumers: perception, purchase pattern, knowledge of production methods, and their readiness/willingness to pay for 0 herbicides / organic products, labels … She studies their behavior, in the kitchen, at home and out of home, and takes part in European projects such as Horizon Europe project “Good”. She also co-leads a working group devoted on Food Transition within the framework of the RMT Filarmoni (mixed technological network) bringing together animal and plant sectors, technical institutes and academic partners.



Wednesday June 14, in the morning (08:45 – 09:30)



Pat J. Brown is a tree nut breeder and Associate Professor in the Dept. of Plant Sciences at UC Davis, where he leads the Walnut Improvement Program and the Pistachio Improvement Program. He received his Ph.D. in Plant Biology from Cornell University in 2008, completed a postdoc at Cornell from 2008-2010, and advanced from Assistant to Associate Professor at the University of Illinois, Urbana-Champaign in the Dept. of Crop Sciences from 2010-2017 before coming to UC Davis. Dr. Brown’s research focuses on integrating genomic and phenomic data into applied plant breeding programs. Target traits in both walnut and pistachio include precocity, kernel quality and composition, and modifying phenology and abiotic stress tolerance to improve resilience to climate change.



Tuesday June 13, in the morning (09:00 – 09:45)

Harnessing genetic diversity in Juglans for sustainable walnut production

Walnut production is threatened by both biotic factors (Xanthomonas blight, insect pests, soil-borne pathogens, and cherry leaf roll virus or CLRV) and abiotic factors (declining winter chill, extreme heat, and water deficit/salinity). Both these threats are characterized by uncertainty: uncertainty about how quickly chemical inputs for biotic control will be phased out, and uncertainty about how climate change will impact production in different walnut growing regions. Adoption of new scion and rootstock cultivars is the most cost-effective long-term solution for the walnut industry,  but carries significant short-term risk for individual growers.

In this presentation I will highlight our efforts in the California Walnut Improvement Program (WIP) to generate new biological knowledge, breeding tools, and improved cultivars of walnut scions and rootstocks. Molecular data are having an increasing influence on scion breeding decisions, but the mutations underlying critical allelic differences remain unknown. An international collaboration to catalog global genetic diversity in Juglans regia resulted in the discovery of a selective sweep possibly associated with walnut domestication. Internal collaboration at UC Davis resulted in a new method for quantifying resistance to Xanthomonas blight and revealed a new source of potential resistance.

Diversity across the Juglans genus remains largely untapped for both rootstock and scion improvement. I will present our strategy for efficient generation and genotyping of Juglans hybrids. A large collaborative effort screening J. microcarpa/J. regia hybrid rootstocks for resistance to multiple soil-borne pathogens unexpectedly revealed a locus with large effects on crown gall resistance, Phytophthora resistance, and vigor. Backcrossing to J. regia is being used to develop CLRV-tolerant rootstocks that maintain vigor and stress resistance comparable to hybrids.

Adoption of any new tree cultivar carries a risk. Our goal in the WIP is to enable individual growers to make data-driven decisions by providing quantitative data, from relevant environments, with complete transparency.



Florent Trouillas is an Associate Professor of Cooperative Extension with the Department of Plant Pathology at the University of California, Davis and the Kearney Agricultural Research and Extension Center. He received a PhD in Plant Pathology in 2009 from the University of California, Davis. Dr. Trouillas specializes in fruit and nut crop pathology and his activities include basic and applied research that aims to elucidate the etiology and biology of plant diseases, and develop Integrated Pest Management strategies. He has established a broad research program that investigates canker, soil borne as well as fruit and foliar diseases of almond, cherry, olive, peach, pistachio, and walnut. His research investigates fungal and bacterial taxonomy, phylogenomic, the molecular detection of plant pathogens as well as the development of biocontrol solutions and cultural alternatives to chemical fungicides. His cooperative extension and education activities include the training of farmers and pest control advisers on disease diagnosis and management. He also serves as a lecturer for various specialized courses in Plant Pathology.



Thursday June 15, in the morning (08:45 – 09:29)

Climate change and plant diseases: opinions, trends, and case studies.

Florent P. Trouillas

Department of Plant Pathology, University of California, Davis, CA 95616, U.S.A and Kearney Agricultural Research and Extension Center, Parlier, CA 93648, U.S.A.

Climate change refers to long-term shifts in temperatures and weather patterns. Although these shifts may occur naturally, human activities since the 1800’s have been broadly accepted as the main driver of climate change, primarily due to the burning of fossil fuels like coal, oil and gas. One major aspect of climate change is the increase of extreme weather events, including cold and heat waves, drought, heavy precipitations, floods and storms. In the current scenario of rapidly evolving climate change and high frequency of extreme weather events, plants are more frequently subjected to stresses of both abiotic and biotic origin. Because most plant pathogens respond to weather, changes in weather events due to climate change are likely to impact the frequency and severity of disease epidemics, thus threatening the global food supply. Numerous scientific reviews have attempted to foresee the impacts of climate change on plant health. Yet, scenario analyses of the potential impact of climate change on plant pathogens are limited. While the impacts of climate change are not easily determined, these could have positive, negative or no impact on individual plant diseases and will vary by region and by crop. Adverse impacts may include disease emergence and outbreaks, increased yield losses, the inefficacy of management strategies and changes in the geographical distribution of plant pathogens. The present review will summarize common opinions and trends related to climate change and plant diseases. Global case studies, adaptation strategies and field observations in California forests and fruit and nut crops will be discussed.

Daniel WIPF


Daniel Wipf is a professor at the University of Burgundy in Dijon. He leads the Mycorrhizae team of the Agroecology Unit (INRAE). His research group has a recognized expertise in the study of the development of arbuscular mycorrhizal symbiosis. It has focused on the early cellular processes involved in the fungal host recognition mechanisms as well as on the nutrient transfer mechanisms at the biotrophic interface. The team is and has been involved in several national and international projects related to molecular genetics, agricultural relevance and functional genomics of plant-microbe interactions.

Daniel Wipf has published more than 70 papers. He has a long experience in collaborative projects: he has been coordinator or partner of several academic projects in Germany and France (German Science Foundation (DFG), French Ministry of Research, Regional Council of Burgundy, COST, DAAD, PROCOPE…), as well as projects in collaboration with industrial partners (ANRT, ANVAR, OSEO, Regional Council of Burgundy Franche Comté). Daniel Wipf is an expert for several national and international structures.


Wednesday June 14, in the morning (10:50 – 11:35)

Is crop happiness under our feet?

Soils are a resource threatened by increasing anthropogenic pressures (IPBES, 2018). Some agricultural practices are the cause of physical degradation of soils, but also of biological degradation, with a decrease in biodiversity and soil organic matter. Other so-called agroecological farming practices, on the contrary, have a positive impact on soil biodiversity. The talk will review agricultural practices in the broad sense of the term, with a focus on their impact on or integration of soil biodiversity, in the light of current societal and environmental challenges.