Comparisons of Phomopsis isolates obtained from sunflower plants and debris in Yugoslavia

Abstract

Six hundred collections of Diaporthe perithecia found on sunflower detritus during a 4-year study yielded Phomopsis helianthi. Two thousand other collections from sunflower plants were also recognized as P. helianthi. Four collections differed from this species in growth rate, colony characteristics, ability to grow at higher temperatures, tolerance to the antagonistic influence of other micro-organisms, ability to produce predominantly or only α-conidia, and failure to form perithecia. Although other Phomopsis species are found on sunflower in Yugoslavia, it is considered that severe outbreaks of the Phomopsis disease of this plant are currently caused only by P. helianthi.