INFECTION OF FLOWERS AND SEED OF PARSNIP BY ITERSONILIA PASTINACAE

Seeding parsnip plants on four commercial holdings in Essex showed not only the root cankers and leaf spots associated with infection by Itersonilia pastinacae, but also extensive lesions on the petioles and necrosis of the inflorescences. These last‐named symptoms were proved to be caused by I. pastinacae which could also be found on some of the seeds. Seed infection, though largely superficial, was sometimes more deep‐seated. It could be eliminated by soaking the seed in an aqueous suspension of 0·2% thiram at 30 °C for 24 h. Heavily infected seed gave a low percentage of seedlings bearing cotyledon lesions: it is uncertain whether hypocotyl lesions, which also occurred, were caused directly by the fungus. An outdoor test failed to show that infected seed gave rise ultimately to roots bearing Itersonilia cankers: the significance of this and other possible sources of infection is discussed. Copyright © 1969, Wiley Blackwell. All rights reserved