Effects of Puccinia xanthii on Xanthium strumarium [Compositae]

Abstract

Plants of Xanthium strumarium L. were inoculated once with Puccinia xanthiiSchw. during the 4 leaf stage, others were inoculated 7 times at ca. 2 week intervals beginning at the 4 leaf stage, and others were protected from rust infection with regular fungicidal spray applications. Attack by P. xanthii was shown to shorten the plant life cycle and reduce plant growth rate and productivity. Burr production was reduced by up to 59% but percentage seed germination remained unchanged. It was concluded that the overall effects of P. xanthii, and not reduced burr production alone, may achieve control of X. strumarium in the field. © 1979 Le François.