Alternaria alternata f. sp. helianthina: a new pathotype of the fungus causing Alternaria leaf spot to sunflower

Pathogenicity tests of Alternaria alternata pathogenic on sunflower were effected on various plants in order to determine the host range of the fungus. Twenty-five plant species, including members of four botanical families of cultivated plants and seven families of weeds were tested in greenhouse experiments for susceptibility to the fungus by artificial inoculations. Among all plants tested sunflower was found to be the only species highly susceptible to this pathogen. To distinguish this A. alternata which attacks sunflower among other known formae speciales of the fungus we propose for it to be named as Alternaria alternata f. sp. helianthina F. sp. nova.