Effect of blackleg and sclerotinia stem rot on canola yield in the high rainfall zone of southern New South Wales, Australia

Kirkegaard, J. A. and Robertson, M. J, and Hamblin, P. and Sprague, S. J. (2006) Effect of blackleg and sclerotinia stem rot on canola yield in the high rainfall zone of southern New South Wales, Australia. Crop & Pasture Science (continuing Australian Journal of Agricultural Research), 57 (2). pp. 201-212.

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Canola (Brassica napus) yields have been declining in the medium–high rainfall (550–650 mm) areas of southern NSW during the 1990s. This decline is not related to seasonal conditions and is not evident in wheat. Leading growers and consultants suspect that increasing levels of the diseases blackleg, caused by Leptosphaeria maculans, and sclerotinia stem rot, caused by Sclerotinia sclerotiorum, may be responsible. We investigated the effect of these diseases on otherwise well-managed canola crops at 2 sites in southern NSW from 2001 to 2003. Blackleg was present at both sites in all 3 years, with 8–10% of plants of variety Rainbow lodged in the untreated plots at Galong in all years, and 1–10% at Wallendbeen. Sclerotinia stem rot was predominately confined to 2001 when 7–42% of plants were infected in the untreated plots at the sites. Individually, or in combination, the diseases caused significant yield losses at both sites in every year of the study, ranging from 0.39 t/ha to 1.54 t/ha. These findings suggest that for each 1% reduction in the incidence of blackleg lodging, yield was increased by 5%, whereas each 1% reduction in plants infected with sclerotinia stem rot increased yield by 1.3%. The ability of the crops to yield to their simulated water and N-limited potential when these diseases were either absent or controlled, indicates that disease may be the key yield-limiting factor in the area. Cost-effective control strategies for both diseases are critical if canola is to remain an important and profitable break crop in the farming system in the high-rainfall zone of southern NSW.

Item Type: Article
Additional Information: We thank Grain Growers Australia and Grains Resaerch and Development Corporation for funding this work through the Best Bet Canola Project administered by Harden and District Rral Advisory Service with adivce from Best Bet Canola Management Committee. We also thank Mr charlie Baldry, Mr Steve Woodhead, and Mr Neil McColl for use of thier land for experiments, and mr Geoff Hose, Mr John Graham and Mr Perter Hines for expert technical assistance.
Uncontrolled Keywords: Leptosphaeria maculans, Sclerotinia sclerotiorum, Brassica napus, Phoma stem canker.
Author Affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
Subjects: Plant Production
Divisions: General
Depositing User: Mr Siva Shankar
Date Deposited: 03 Jul 2012 03:25
Last Modified: 03 Jul 2012 03:26
Official URL: http://dx.doi.org/10.1071/AR05179
URI: http://eprints.icrisat.ac.in/id/eprint/6461

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