Monday, November 13, 2006

Evaluation of Canola Cultivars for Resistance to Sclerotinia.

Robert Henson1, Paul Porter2, David Legare3, and Mathew Swanson1. (1) NDSU, Carrington Research Extension Center, PO Box 219, Carrington, ND 58421, (2) University of Minnesota, Dept Agron/Plt Gen-411 Borlaug Hall, Univ. of Minn. 1991 Buford Cir., St. Paul, MN 55108-6026, (3) Monsanto, Monsanto, 910 6th Ave NE, Dilworth, MN 56529

The objective of this project is to identify canola (Brassica napus L.) cultivars which are less susceptible to Sclerotinia.  In 2005, field trials were conducted at the North Dakota State University Carrington Research Extension Center and an on-farm site near Red Lake Falls, Minnesota.  Twenty-six canola cultivars, representing current production varieties and private breeding lines, were evaluated in a randomized complete block design with four replicates.  Plot size was approximately seven 7-inch rows x 25 feet.  At flowering, plots were inoculated with ascospores (foliar spray) and misted until physiological maturity to provide a favorable environment for disease development.  Disease incidence and severity were evaluated, as well as plant height and lodging at maturity and grain yield, test weight, and oil concentration at harvest.  Data were analyzed by standard statistical procedures and means were compared by F-protected LSD.  Weather during flowering was exceptionally hot and dry and the inoculations with ascospores were probably ineffective.  Minimal disease pressure was achieved at Red Lake Falls (only two plots had disease incidence greater than 6%).  At Carrington, heavy misting late in the season stimulated germination of residual sclerotia from the 2004 sunflower head rot trial, which resulted in significant disease pressure (incidences ranging from 4.5 to 68.5%).  However, the disease attacked relatively late, favoring the entries which were close to physiological maturity (a 14-day range was recorded in the date of physiological maturity).  Highly significant negative correlations were observed between disease incidence and days to flowering and physiological maturity, plant height, yield, and seed size.  Disease was highly and positively correlated with lodging.  One application of Endura fungicide reduced Sclerotinia incidence in both varieties which were treated, but yield was not increased due to the lateness of disease pressure.