Submitted to: Biological and Cultural Tests for Control of Plant Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 18, 2002
Publication Date: May 5, 2002
Citation: Hanson, L.E., Panella, L.W. 2002. Beta pis from the usda-ars npgs evaluated for resistance to cercospora beticola, 2001.. Biological and Cultural Tests for Control of Plant Diseases. Interpretive Summary: Cercospora leaf spot is one of the most widespread and destructive fungal disease of beet and occurs wherever beets are grown. One important method of managing the disease is the use of cultivars with resistance to the pathogen, Cercospora beticola. In an ongoing effort to find sources of resistance to Cercospora, 30 Plant Introdcutions (PIs) from the USDA-ARS National Plant Germplasm System were tested for resistance to the leaf-spotting fungus, Cercospora beticola. Due to the hot, dry weather, disease development was slow and the disease was moderate. Significant variability was detected between different entries. Several PIs were not significantly different from the resistant control and, on the final rating date, five accessions were rated significantly lower than the resistant control.
Technical Abstract: Thirty Plant Introductions (PIs) from the USDA-ARS National Plant Germplasm System were evaluated in an artificially produced epiphytotic for resistance to Cercospora beticola at the Crops Research Lab-Fort Collins Research Farm in CO. Internal controls included a highly susceptible synthetic check, SP351069-0, and a resistant hybrid check, (FC504 X FC502/2) X SP6322-0. The nursery was inoculated twice with Cercospora beticola.. Visual evaluations on the plot, producing a disease index (DI) on a scale from 0 (no disease) to 10 (plant dead), were made on three dates, with the peak of the epidemic occurring on or after the last date. The high temperatures in the summer of 2001, combined with low moisture, made it difficult to keep the humidity in the nursery high, and contributed to a moderate leaf spot epidemic. At our third evaluation, means of the resistant and susceptible internal control were 4.5 and 6.0, respectively, across the nursery. In 2000, these means were 2.4 and 3.8, respectively. Means of the PIs ranged from 2.0 to 8.0. An analysis of variance on the disease indices determined that there were significant differences among entries (P=0.05) on all three dates of evaluation. A number of accessions were not significantly different from the resistant control and on the last rating, five accessions had ratings significantly lower than the resistant control.