The role of pycnidiospores of Leptosphaeria maculans in the spread of blackleg disease in rape

Abstract

The development and spread of blackleg leaf, stem and crown infections in rape plants (Brassica napus cv. Zephyr), caused by Leptosphaeria maculans pycnidiospores, was examined under field conditions for plants artificially inoculated at 3, 5 1/2 and 8 1/2 weeks of age. Spread of leaf, stem and crown infections, via pycnidiospores, occurred for inoculations made on 3- and 5 1/2-week-old plants. Inoculation at three weeks oflage resulted in theigreatest disease spread. There was no leaf infection spread and very little stem and crown infection spread for the inoculation made on the 8 1/2-week-old plants.