The composition of this parasitic complex seems to fluctuate across geographic locations, but also over time during the epidemic. alternata, but a number of other species have been isolated and identified from diseased organs. The two major species are Alternaria solani and A. One of the challenges about early blight is the large diversity of Alternaria species involved. Multidrug resistance to one or more chemical families is now detected in many European and worldwide populations of these pathogens, as shown in the Euroblight surveys which now also include early blight. Third, Alternaria species causing early blight are often able to develop resistance to major unisite fungicides. As these molecules are progressively being withdrawn from use in favour of either alternative products or of more specific active ingredients, targeting late blight only, early blight reappears and increases in severity. Second, the disease was previously held under very good control by the repeated, preventative applications of multisite fungicides also used to control late blight. First, the current change in climate across our continent tends to foster earlier and more rapid attacks by Alternaria than in the past, due to warmer temperatures and accelerated crop senescence. However, both diseases can co-exist on the same crop, and even on the same plant, whenever conditions are favourable.Įarly blight severity and incidence are now rapidly expanding in European crops, for at least three reasons. Early blight is a severe problem in continental climates, while late blight is most prevalent in oceanic areas. Like late blight, it affects both the leaves and stems, but also the fruits (tomato) or tubers (potato) of diseased crops. ![]() Indeed, both are also affected by early blight, caused by a range of Alternaria species.Įarly blight is characterised by target-shaped foliar spots, expanding over time. However, it is not the only foliar blight of these crops. Late blight, caused by Phytophthora infestans, is certainly the most feared disease of potato and tomato worldwide. Discussing late blight, Dr Didier Andrivon of INRA asks: is it the top (or bottom) of a much larger, re-emerging parasitic complex ?
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