Effects of previous cropping and fungicide timing on the development of light leaf spot (Pyrenopeziza brassicae ) seed yield and quality of winter oilseed rape (Brassica napus )

A - Papers appearing in refereed journals

Figueroa, L., Shaw, M. W., Fitt, B. D. L., McCartney, H. A. and Welham, S. J. 1994. Effects of previous cropping and fungicide timing on the development of light leaf spot (Pyrenopeziza brassicae ) seed yield and quality of winter oilseed rape (Brassica napus ). Annals of Applied Biology. 124 (2), pp. 221-239.

AuthorsFigueroa, L., Shaw, M. W., Fitt, B. D. L., McCartney, H. A. and Welham, S. J.
Abstract

Light leaf spot, caused by Pyrenopeziza brassicae, was assessed regularly on double-low cultivars of winter oilseed rape during field experiments at Rothamsted in 1990-91 and 1991-92. Previous cropping and fungicide applications differed; seed yield and seed quality were measured at harvest. In each season, both the initial incidence of light leaf spot and the rate of disease increase were greater in oilseed rape crops sown after rape than those sown after cereals. The incidence of diseases caused by Phoma lingam or Alternaria spp. was also greater in second oilseed rape crops. In 1991-92 there was 42% less rainfall between September and March than in 1990-91, and much less light leaf spot developed. However, P. lingam and Alternaria spp. were more common. Only fungicide application schedules including an autumn spray decreased the incidence of light leaf spot on leaves, stems and pods, as indicated by decreased areas under the disease progress curves (AUDPC) and slower rates of disease increase. Summer sprays decreased incidence and severity of light leaf spot on pods only. In 1990-91, all fungicide treatments which included an autumn spray increased seed and oil yields of cv. Capricorn but only the treatment which included autumn, spring and summer sprays increased yields of cv. Falcon. No treatment increased the yields of cv. Capricorn or cv. Falcon in 1991-92. Fungicide applications decreased glucosinolate concentrations in the seed from a crop of cv. Cobra severely infected by P brassicae in 1990-91, but did not increase yield.

KeywordsAgriculture, Multidisciplinary
Year of Publication1994
JournalAnnals of Applied Biology
Journal citation124 (2), pp. 221-239
Digital Object Identifier (DOI)doi:10.1111/j.1744-7348.1994.tb04130.x
Open accessPublished as non-open access
Funder project or code102
900
913
101
204
207
ISSN00034746
PublisherWiley

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