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Relationship between weather, colonization and mycotoxins produced by Fusarium graminearum species complex on sorghum grain

Lisa Rothmann: University of the Free State

<div>Sorghum grain mold (SGM) is one of the most important biotic constraints in sorghum production. The <em>Fusarium graminearum </em>species complex (<em>Fg</em>SC) is responsible for the majority of important mycotoxins associated with SGM, including deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEA). Weather variables that favour SGM development with specific reference to <em>Fg</em>SC colonisation and concomitant mycotoxin production were studied with the aim of developing a risk forecast model. Sorghum grain was collected from field trials from 2007-2014 at 11 South African sorghum production localities. Site-specific weather data were also collected for each locality. Grain samples were analysed for <em>Fg</em>SC colonisation using qPCR and mycotoxin (DON, NIV and ZEA) contamination with LC-MS-MS. Multivariate data analyses were completed using GenStat (18<sup>th</sup> Ed.). <em>Fg</em>SC colonisation and concomitant mycotoxin accumulation coincided with weather conditions during late flowering and soft-dough stage of grain development, which are the critical periods for disease development. Grain characteristics also influenced mycotoxin production. An epidemiological model which identifies specific sorghum production risk regions, will enable producers to ensure that timely management decisions are made to reduce <em>Fg</em>SC infection and mycotoxin contamination.</div>