Disruption of the ‘disease triangle’ by chemical and physical environmental change

Abstract

The physical and chemical environment of the Earth has changed rapidly over the last 100 years and is predicted to continue to change into the foreseeable future. One of the main concerns with potential alterations in climate is the propensity for increases in the magnitude and frequency of extremes to occur. Even though precipitation is predicted to increase in some locations, in others precipitation is expected to decrease and evapotranspiration increase with air temperature, resulting in exacerbated drought in the future. Chemical [ozone (O3 ) and other air contaminants] and subsequent physical alterations in the environment will have a profound effect on the 'disease triangle' (a favourable environment, a susceptible host and a virulent pathogen) and should be included in any analysis of biological response to climate change. The chemical and physical environment affects plant health and alters plant susceptibility to insect and pathogen attack through increased frequency, duration and severity of drought and reduction in host vigour. The potential effects of climate change and O3 on tree diseases with emphasis on the western United States are discussed. We describe a generalised modelling approach to incorporate the complexities of the 'disease triangle' into dynamic vegetation models.

Enzyme activity modification in adult beetles (Agelastica coerulea) inhabiting birch trees in an ozone-enriched atmosphere

“…Global change and O 3 -induced alterations in plants may alter the suitability of plants to insects, thus affecting plant-insect interactions in a complex manner (Jøndrup et al 2002;Valkama et al 2007;Lindroth 2010;Jamieson et al 2017). In addition, the disease triangle conceptual model, which indicates the interactions among the environment, a plant, and a stressor agent, may be disrupted (Chappelka and Grulke 2016).…”

Effects of soil nutrient availability and ozone on container-grown Japanese larch seedlings and role of soil microbes

“…This increase in B content may be part of a defense mechanism of plants against Fusarium sp. for reducing or controlling disease severity (Dong et al 2016;Jiang et al 2016) and suggests a potentially important role for B in reducing disease development (Chappelka and Grulke 2016). Further studies should assess the role of B in stress and disease biology over time and for different experimental setups to confirm that its role in a stress-defense mechanism.…”

“…Elevated O 3 uptake by stomata can inhibit leaf area growth, decrease carbon uptake and Rubisco and chlorophyll content, alter growth, and suppress productivity of forest plants (Paoletti and Grulke 2005;Wittig et al 2009;Jolivet et al 2016;Li et al 2017a, b;Cailleret et al 2018). Because of the negative O 3 effects on forest plants and associated ecological processes (Karnosky et al 2005;Ainsworth et al 2012;Blande et al 2014;Agathokleous et al 2016b;Chappelka and Grulke 2016;Braun et al 2017), we must understand the biology of O 3 -induced stress and devise innovative methods to mitigate the deleterious effects of O 3 .…”

Plants and the changing environment

“…). Global climate change is altering plant–pest interactions, leading to new conceptual frameworks for effects of temperature and ozone on the traditional disease triangle of environment–host vigour–pathogen virulence (Chappelka & Grulke ), with emphasis on the western United States. Positive feedbacks between plant responses to stress and physiological responses that may further accelerate climate change are also considered.…”

“…An important aspect of plant response to climate change is the alteration of competitive interactions, across and within trophic levels, including drought impacts on weed species (R€ uhl et al 2016). Global climate change is altering plant-pest interactions, leading to new conceptual frameworks for effects of temperature and ozone on the traditional disease triangle of environment-host vigour-pathogen virulence (Chappelka & Grulke 2016), with emphasis on the western United States. Positive feedbacks between plant responses to stress and physiological responses that may further accelerate climate change are also considered.…”