Management of the greenhouse microclimate in relation to disease control: a review

Abstract

-The microclimate of the greenhouse when considered as a relatively homogeneous entity is well understood, and there are models of crop growth, and environmental parameters that enable expert decision-support systems to be derived, and automatic environment controls affecting productivity to be designed. However, the microbial microclimate of pathogens in the boundary layer on the phylloplane is poorly understood, and disease escape measures are not yet incorporated into automatic environment control systems. Because biocontrol microorganisms necessarily inhabit the same ecological niche as microbial pathogens, describing environments on the phylloplane that encourage biological control without also enhancing pathogenesis presents very difficult engineering challenges. This review examines the dilemmas in designing environments that maximise productivity, encourage disease escape, and permit biological control. expert system / greenhouse microclimate / biological control / disease forecasting / epidemic modelling / disease escape Résumé -Mise au point : la conduite du microclimat en serre en relation avec le contrôle des maladies. Le microclimat des serres, lorsqu'il est considéré comme une entité homogène, est bien connu. Il existe ainsi des modèles simulant la croissance des plantes et les paramètres environnementaux qui permettent d'élaborer des systèmes experts d'aide à la décision et des dispositifs automatiques de contrôle de l'environnement pour améliorer la production. Cependant, le microclimat qui affecte la flore pathogène dans la couche limite du phylloplan, est mal connu, et, à l'heure actuelle, on ne sait pas comment incorporer les mesures d'échappe-ment aux maladies dans les systèmes de contrôle automatique de l'environnement. Comme les micro-organismes utilisés pour la lutte biologique occupent nécessairement la même niche écologique que les organismes pathogènes, la description des environnements sur le phylloplan qui favorisent la lutte biologique sans accroître le développement des organismes pathogènes, présente de grandes difficultés technologiques. Cette mise au point examine le dilemme auquel il faut faire face pour la mise au point d'environnements qui permettent d'obtenir de bonnes récoltes, favorisent l'échappement aux maladies et, en même temps, permettent la lutte biologique. systèmes experts / microclimat en serre / lutte biologique / prévision de maladies / modélisation épidémiologique / échappement aux maladies

Design for an improved temperature integration concept in greenhouse cultivation

“…based on the underlying processes rather than an overall low relative humidity set point could, therefore, most probably increase energy saving and possibilities for optimal climate control. Until now energy saving strategies have mainly been focussed on temperature and more advanced humidity control was mainly developed in relation to disease control (Jewett and Jarvis, 2001). For an overall approach, one should take both advanced temperature and advanced humidity control into account.…”

Amblyseius swirskii in greenhouse production systems: a floricultural perspective

“…Also greenhouse design (e.g., concrete floors, sub-irrigation compared to overhead irrigation and open floors, polyethylene vs. glass covering) leads to big differences in ambient humidity. When considering the influence of environmental conditions on small plant-dwelling insects and mites, it should be noted that the microclimate at the phylloplane can be very different from ambient conditions (Jewett and Jarvis 2001;Boulard et al 2004) so conditions measured at the leaf surface provide a much better indication of the environment of pests and biological control agents. As A. swirskii originates from humid coastal areas in the Mediterranean (Porath and Swirski 1965;de Moraes et al 2004), it is adapted to high temperatures and relative humidity.…”

Principles of Plant Health Management for Ornamental Plants

“…The primary aim of environmental control of disease in a greenhouse is to restrict water availability to the pathogens, as bacteria and fungi need moisture in order to infect. Computer controls are used to make automatic adjustments in ventilation or heating to effect dehumidification in response to indications that the temperatures are nearing the dew point (86). Precise measurements of very low vapor pressure deficits, when relative humidity is greater than 90%, are particularly important.…”