The biology of Puccinia chondrillina a potential biological control agent of skeleton weed

Abstract

SUMMARYDuring investigations on the parasites of Chondrillajuncea in the Mediterranean region, the rust, Puccinia chondrillina, was found to be one of the most damaging. This macrocyclic and autoecious rust which is specific to the genus Chondrilla, remains active throughout the year and attacks all stages and all parts of the plant. In the Mediterranean region the rust appears to multiply solely by the uredo‐stages and the teleutospores produced at the end of the summer have no obvious role in the life‐cycle of the fungus. The uredospores germinated at temperatures of 0–36 °C and were used for inoculation of Chondrilla seedlings in the greenhouse.The rust occurs from the cold continental climates of southern Siberia to the hot, Mediterranean ones of Portugal and North Africa. In many situations the rust has been found to play an important role in the reduction of C. juncea populations. Young seedlings were highly susceptible to attack and were often destroyed. Older rusted plants gave many fewer viable seeds than healthy plants and were also often unable to produce new rosettes from their roots.