Plant disease management strategies under changing climatic scenario.

摘要

Disease outbreaks occur with changes in climatic conditions such as temperature and moisture that favor the growth, survival and dissemination of pathogens. A change in climatic condition can help or force the disease to expand its normal range to new environments and leads to epidemic. Global climate changes especially increased CO₂ temperature and moisture levels are thought to influence or change all the elements of a disease triangle. The most obvious effect of climate change is on global mean temperature which is expected to rise between 0.9 and 3.5 C by the year 2100. This increase in temperature can modify host physiology and resistance. Increased CO₂ would affect the physiology, morphology and biomass of crops, by promoting the development of some rusts and other foliar diseases. High moisture (rainfall) favors most of the foliar diseases and soil borne pathogens. Climate change can have positive, negative or neutral impact on disease management due to more pathogen generations per season, evolution of aggressive pathogenic races which may cause threat to resistance may affect the efficacy of crop protection chemicals by altering the dynamics of fungicides residues on the crop foliage, uptake, translocation and metabolism of systemic fungicides. Climate change will cause alteration in the disease geographical and temporal distributions and consequently appropriate control methods will have to be adopted to this new reality. The disease management strategies with changing climatic scenario include monitoring of epiphytotics or conducive environment and host-parasite interactions. Crops like wheat and oats are becoming more susceptible to rust diseases with increased temperature, and dry root rot of chickpea (Rhizoctonia bataticola) is becoming more severe in rainfed environments. In the long term it is necessary to select varieties that will tolerate variable climatic conditions and are more disease resistant. From a disease management viewpoint, information is generally required for a specific disease at a field scale. Hence, data on potential impact of climate change on diseases and their dynamics need to be assessed and reevaluated over a period of time to devise suitable management practices.