2 research outputs found
Short-term relationships between climate and grapevine trunk diseases in southern French vineyards
International audiencehttps://ives-openscience.eu/13062/An increasing plant dieback has been observed in vineyards these past two decades that has been partly attributed to the incidence of grapevine trunk diseases. Among them, esca and Botryosphaeria dieback are increasingly affecting grapevine mortality and yield loss, but little is known about the relationships between leaf symptoms and climate, hampering our ability to predict future trends in grapevine dieback. Our aim was to test short-term relationships between weather conditions and leaf symptom incidence in southern France vineyards. We harmonized and compiled summer surveys leaf symptoms of grapevine trunk disease in a database gathering 50 vineyards. Surveys were conducted on a weekly to bimonthly basis during the period 2003-2021, leading to 69 site-by-year plots. Vineyards were characterised by different ages (8 to 37 years old plants), grapevine varieties (n = 11), cultural practices, soil and climate conditions. Climate data were compiled from Safran daily data of Météo-France and averaged on different time steps. For each plot, we derived weekly rates of leaf symptom incidence using non-parametric Loess models. To account for contrasting conditions among vineyards, we scaled both leaf symptom and climate data, focusing on variations relative to plot. Statistical models show highly significant relationships between local leaf symptom trends and climatic conditions on a weekly to monthly time step. As expected, the higher the evaporative demand (temperature and humidity) the higher the incidence of new weekly cases. However, an increase in drought conditions and wind speed inhibited the incidence of leaf symptoms. Our results suggest that fungi associated with grapevine trunk diseases benefit from warm conditions but are inhibited by dry conditions that both are expected to increase in the next future. Our findings provide important insights to better understand plant- climate-diseases relationships in the field and anticipate trends for the next decades
Pathogenic and beneficial microorganisms in soilless cultures
Soilless cultures were originally developed to control soilborne diseases. Soilless
cultures provide several advantages for growers such as greater production of crops,
reduced energy consumption, better control of growth and independence of soil quality.
However, diseases specific to hydroponics have been reported. For instance,
zoospore-producing microorganisms such as Pythium and
Phytophthora spp. are particularly well adapted to aquatic
environments. Their growth in soilless substrates is favoured by the recirculation of the
nutrient solution. These pathogenic microorganisms are usually controlled by disinfection
methods but such methods are only effective as a preventive measure. Contrary to
biofiltration, active treatments such as UV, heat and ozonisation have the disadvantage of
eliminating not only the harmful microorganisms but also the beneficial indigenous
microorganisms. Here, we review microbial populations that colonise ecological niches of
hydroponic greenhouse systems. Three topics are discussed: (1) the general microflora; (2)
the pathogenic microflora that are typical to hydroponic systems; and (3) the
non-pathogenic and possibly beneficial microflora, and their use in the control of plant
diseases in soilless greenhouse systems. Technical, economic and environmental concerns
are forcing the adoption of new sustainable methods such as the use of microbial
antagonists. Thus, increased attention is now focused on the role of natural microflora in
suppressing certain diseases. Managing disease suppression in hydroponics represents a
promising way of controlling pathogens. Three main strategies can be used: (1) increasing
the level of suppressiveness by the addition of antagonistic microorganisms; (2) using a
mix of microorganisms with complementary ecological traits and antagonistic abilities,
combined with disinfection techniques; and (3) amending substrates to favour the
development of a suppressive microflora. Increasing our knowledge on beneficial
microflora, their ecology and treatments that influence their composition will help to
commercialise new, ready-to-use substrates microbiologically optimised to protect plants
in sustainable management systems