Occurrence of Puccinia xanthii Schw. on cockleburs in Hungary

Abstract

Puccinia xanthii Schw., a widespread rust on cocklebur species, is possible be used as a biological agent in control of these weeds. There have been, however, some reports about certain hybrids of sunflower infected with this rust from several parts of the world. This rust was observed for the first time on the Italian cocklebur in Hungary in 2002. Since then, infections of cockleburs occurred yearly in advanced growing season. P. xanthii has not yet infected any of 15 hybrids of sunflower grown in Hungary, either in a field experiment or in the greenhouse. Ambrosia artemisiifolia grown together with infected cockleburs have not developed symptoms of presence of P. xanthii under field conditions since the first occurrence of the rust in Hungary. Although the rust can infect cockleburs even at their cotyledonous stage, natural infections start in the second part of the growing season, so the role of P. xanthii seems to be without significance in biological control of cockiebur species in Hungary at present.