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Title: BETA PIS FROM THE USDA-ARS-NPGS EVALUATED FOR RESISTANCE TO CERCOSPORA BETICOLA, 2002

Author
item Hanson, Linda
item Panella, Leonard

Submitted to: Biological and Cultural Tests for Control of Plant Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2003
Publication Date: 6/30/2003
Citation: HANSON, L.E., PANELLA, L.W. BETA PIS FROM THE USDA-ARS-NPGS EVALUATED FOR RESISTANCE TO CERCOSPORA BETICOLA, 2002. BIOLOGICAL AND CULTURAL TESTS FOR CONTROL OF PLANT DISEASES. 2003.

Interpretive Summary: 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, C. beticola. Due to the dry weather and moderate nighttime temperatures, disease development was slow and the disease was moderate. Significant variability was detected between different entries. One accession had a significantly lower disease rating than the susceptible control at all rating dates.

Technical Abstract: 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 low moisture in the summer of 2002 made it difficult to keep the humidity in the nursery high, and contributed, with moderate nighttime temperatures, to a moderate leaf spot epidemic. At our third evaluation, means of the resistant and susceptible internal control were 3.8 and 4.5, respectively, across the nursery. In 2001, these means were 4.5 and 6.0, respectively. Means of the PIs ranged from 3.0 to 5.0. 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. One accession was significantly different from the susceptible control at all three ratings.