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United States Department of Agriculture

Agricultural Research Service

Research Project: Multidisciplinary Approaches to Enhanced Sugar Beet Germplasm

Location: Sugarbeet Research

Title: Evaluation of Beta PIs from the USDA-ARS, NPGS for Rhizoctonia crown and root rot resistance, 2013

Authors
item Panella, Leonard
item Vagher, Travis
item Fenwick, A -

Submitted to: Plant Disease Management Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 20, 2014
Publication Date: April 22, 2014
Citation: Panella, L.W., Vagher, T.O., Fenwick, A.L. 2014. Evaluation of Beta PIs from the USDA-ARS, NPGS for Rhizoctonia crown and root rot resistance, 2013. Plant Disease Management Reports. 8:FC178.

Interpretive Summary: Thirty sea beet accessions from the Beta collection of the USDA-ARS National Plant Germplasm System were screened for resistance to Rhizoctonia root and crown rot, at the USDA-ARS Fort Collins, CO Research Farm. The Rhizoctonia screening nursery in 2013 was a randomized complete-block design with five replications. Seed was planted on 28 May and no herbicides were used this year. Inoculation with dry, ground, barley grain inoculum of Rhizoctonia solani was applied to the crown of the plants on July 25. Beets were harvested on October 23 and each root was rated for rot on a scale of 0 (no damage) to 7 (dead plant with root completely rotted). Average disease severity per plot was determined to create a disease index (DI) for each entry. Screening annual sea beet is always difficult because the seed germinates and establishes poorly. Plots contained between 1 and 16 individual plants. There was a good separation between resistant and susceptible entries, although the susceptible control scored lower (more resistant) than expected. An analyses of variance was performed showing highly significant differences among entries’ DIs. The 10 entries with the lowest DI and entry PI 604534 were not significantly different from the highly resistant control (FC705/1). Those accessions, which were not significantly less resistant than the resistant control, will be retested and, if the resistance is confirmed, entered into the USDA-ARS rhizoctonia root rot-resistance breeding program at Fort Collins, CO to develop sugar beet germplasm with increased resistance to rhizoctonia root rot.

Technical Abstract: Thirty sea beet (Beta vulgaris subsp. maritima (L.) Arcang accessions from the Beta collection of the USDA-ARS National Plant Germplasm System were screened for resistance to Rhizoctonia root and crown rot, at the USDA-ARS Fort Collins, CO Research Farm. The Rhizoctonia screening nursery in 2013 was a randomized complete-block design with five replications. Seed was planted on 28 May and no herbicides were used this year. Inoculation with dry, ground, barley grain inoculum of Rhizoctonia solani isolate R-9 (AG-2-2) was applied to the crown of the plants on July 25 at a rate of 6.11 g/m of row. Beets were harvested on October 23 and each root was rated for rot on a scale of 0 (no damage) to 7 (dead plant with root completely rotted). Average disease severity per plot was determined to create a disease index (DI) for each entry. Screening annual sea beet is always difficult because the seed germinates and establishes poorly. Plots contained between 1 and 16 individual plants. There was a good separation between resistant and susceptible entries, although the susceptible control scored lower (more resistant) than expected. An analyses of variance was performed showing highly significant differences among entries’ DIs. Results reported are based Dunnett’s one-tailed t-test (p = 0.05) of the rank transformed data. The 10 entries with the lowest DI (< 2.7) and entry PI 604534 were not significantly different from the highly resistant control (FC705/1). Those accessions, which were not significantly less resistant than the resistant control, will be retested and, if the resistance is confirmed, entered into the USDA-ARS rhizoctonia root rot-resistance breeding program at Fort Collins, CO to develop sugar beet germplasm with increased resistance to rhizoctonia root rot.

Last Modified: 7/25/2014
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