Development of phoma lesions on oilseed rape leaves inoculated with ascospores of A-group or B-group Leptosphaeria maculans (stem canker) at different temperatures and wetness durations
Article first published online: 9 OCT 2008
Volume 50, Issue 1, pages 28–41, February 2001
How to Cite
Toscano-Underwood, C., West, J. S., Fitt, B. D. L., Todd, A. D. and Jedryczka, M. (2001), Development of phoma lesions on oilseed rape leaves inoculated with ascospores of A-group or B-group Leptosphaeria maculans (stem canker) at different temperatures and wetness durations. Plant Pathology, 50: 28–41. doi: 10.1046/j.1365-3059.2001.00526.x
- Issue published online: 9 OCT 2008
- Article first published online: 9 OCT 2008
- Accepted 20 July 2000.
- incubation period;
- infection conditions;
- Leptosphaeria maculans;
- phoma leaf spot;
- stem canker;
- winter oilseed rape
In controlled-environment experiments, ascospores of both A-group and B-group Leptosphaeria maculans were able to infect leaves of oilseed rape and produce phoma leaf spot lesions at temperatures from 5 to 20°C and wetness durations from 8 to 72 h after inoculation. Lesions formed on leaves inoculated with B-group ascospores had few pycnidia and were darker, smaller and less noticable than the larger, pale grey lesions with many pycnidia produced by A-group ascospores. Lesions formed by A-group or B-group L. maculans on naturally infected winter oilseed rape experimental crops were similar to lesions produced by the two groups on inoculated plants. The greatest numbers of lesions were produced with a leaf wetness duration of 48 h and at temperatures of 15–20°C for both A-group and B-group ascospores. As leaf wetness duration and temperature decreased below the optimal values, the number of lesions decreased. The incubation period, estimated as the time from inoculation to the appearance of the first lesions (t1), or the time to the appearance of 50% of the lesions (t50), of B-group was often shorter than that of A-group L. maculans. As temperature decreased below 20°C, the length of the incubation period of both A-group and B-group L. maculans increased.