Species prevalence and disease progression studies demonstrate a seasonal shift in the Alternaria population composition on potato. (17th August 2017)

• Record Type: Journal Article
• Authors: Vandecasteele, M.; Landschoot, S.; Carrette, J.; Verwaeren, J.; Höfte, M.; Audenaert, K.; Haesaert, G.
• Is Part Of: Plant pathology. Volume 67:Number 2(2018)
• Page Start: 327
• Page End: 336
• Publication Date: 2017-08-17
• Subjects: Alternaria -- population composition -- potato -- real‐time PCR -- virulence -- weather; Agricultural pests -- Periodicals; Plant diseases -- Periodicals; 632
• DOI: 10.1111/ppa.12734
• Languages: English
• ISSNs: 0032-0862

Abstract

Abstract : To assess the incidence of early blight/brown spot (EB/BS) in Flanders (Belgium), potato fields in 22 locations were monitored and scored over the duration of the growing seasons 2014 and 2015. The average disease incidence was shown to be higher in 2014 than in 2015. Soil type, rainfall and temperature were also analysed in relation to disease incidence. In 2014, potato plants grown in sandy soils had more EB/BS disease than those grown in clay or loamy soils. However, the low disease incidence in 2015 meant that differences in disease levels between soil types could not be discerned for that growing season. A windowpane analysis demonstrated that rainfall and humidity accounted for the differences in disease incidence between the two growing seasons. During the course of the survey, the species composition in leaves with symptoms was assessed using real‐time PCR. Remarkably, small‐spored Alternaria species, such as A. alternata and A. arborescens, rather than the more virulent A. solani were the predominant species on potato leaves throughout the growing season. As the disease progressed, the proportion of A. solani increased. In view of these results, the virulence of a collected set of Alternaria isolates was assessed by an in vitro assay. Despite A. solani being more virulent than A. alternata or A. arborescens, the most abundant species isolated from potato leaves with symptoms was A. arborescens .