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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Soil Management and Sugarbeet Research » Research » Publications at this Location » Publication #329037
Title: Sugar beet breeding lines evaluated for resistance to Rhizoctonia crown and root rot in Fort Collins, CO, 2015

Author
item Panella, Leonard
item Vagher, Travis
item Fenwick, Ann

Submitted to: Plant Disease Management Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2016
Publication Date: 9/5/2016
Citation: Panella, L.W., Vagher, T.O., Fenwick, A.L. 2016. Sugar beet breeding lines evaluated for resistance to Rhizoctonia crown and root rot in Fort Collins, CO, 2015. Plant Disease Management Reports. 10:FC166.

Interpretive Summary: Thirty-nine beet sugar beet breeding lines (Beta vulgaris subsp. vulgaris) from the USDA-Agricultural Research Service breeding program at Fort Collins, CO, were screened for resistance to Rhizoctonia crown and root rot (Rcrr) at the Colorado State University ARDEC facility in Fort Collins, CO. Sugar beet seed was planted on June 9. An inoculum of dry, ground, hulless-barley grain, infested with Rhizoctonia , was applied to the crown of the plants on July 28. Roots were harvested on September with a single row lifter, and each root was rated for rot on a scale of 0 (no disease) to 7 (dead plant, leaves necrotic with root completely rotted). The crop was planted and immediately irrigated to promote germination. The amount of moisture from planting to harvest was 9.30 cm of rainfall and 33.02 cm of irrigation water via an overhead linear irrigation system. Temperatures were warm through harvest. Disease progression was excellent and at harvest we had severe levels of rhizoctonia crown and root rot in our plots. There were highly significant differences among entries for Disease Index in this year’s test and there was a very good separation between resistant and susceptible entries. The most resistant entry was FC709-2 and three entries were not significantly different from FC709-2 (20121034). 200401010HO is an O-type maintainer line, and 20071013 is the resistant germplasm, FC220, which was released and registered in 2008. The other line is a cross between O-type, Fort Collins germplasm FC708 and multigerm, East Lansing germplasm EL 51. These three lines will be considered for release. There are a number of entries that were significantly more resistant than the worst performing germplasm (20141009) but not as resistant and the most resistant germplasm (FC709-2). These lines will be retested and further selected for resistance to Rcrr and other important sugar beet diseases before a decision to release is made. These results will be accessible to interested parties through the USDA-ARS, NPGS GRIN database (http://www.ars-grin.gov/npgs/index.html).

Technical Abstract: Thirty-nine beet sugar beet breeding lines (Beta vulgaris subsp. vulgaris) from the USDA-Agricultural Research Service breeding program at Fort Collins, CO, were screened for resistance to Rhizoctonia crown and root rot (Rcrr) at the Colorado State University ARDEC facility in Fort Collins, CO. The 2015 Rhizoctonia screening nursery was a completely randomized design with five replicates in one-row plots (76 cm row spacing) 3.7 m long. In 2015, the field was not fertilized due to available nitrogen and was bedded on June 2. Sugar beet seed was planted on June 9. An inoculum of dry, ground, hulless-barley grain, infested with Rhizoctonia solani isolate R-9 (AG-2-2), was applied to the crown of the plants on July 28 (at the 8-12 leaf growth stage) at a rate of 7.0 g m-1 of row. The field was cultivated afterwards to place soil onto the plant crowns. Roots were harvested on September with a single row lifter (pulled and cleaned by hand), and each root was rated for rot on a scale of 0 (no disease) to 7 (dead plant, leaves necrotic with root completely rotted). Average disease severity per plot (DI) was determined and an ANOVA was performed using with a Tukey-Kramer separation with an LSD (p=0.05) on DI. Percent of healthy roots (classes 0 and 1 combined) and harvestable roots (classes 0 through 3) were calculated. Data in classes 0-1 and 0-3 were transformed using arcsine square root to normalize the data for analyses (AP 0-1 and AP 0-3, respectively), and an ANOVA (PROC GLM) used to generate LSD values. The crop was planted and immediately irrigated to promote germination. The amount of moisture from planting to harvest was 9.30 cm of rainfall and 33.02 cm of irrigation water via an overhead linear irrigation system. Temperatures were warm through harvest. Disease progression was excellent and at harvest we had severe levels of rhizoctonia crown and root rot in our plots. There were highly significant differences among entries for Disease Index in this year’s test and there was a very good separation between resistant and susceptible entries. The most resistant entry was FC709-2 (one of two highly resistant control lines) and three entries and two resistant checks (FC705/1 and FC703) were not significantly different from FC709-2 (20121034). 200401010HO is an O-type maintainer line, 20071013 is the resistant germplasm, FC220, which was released and registered in 2008. The other line is a cross between O-type, Fort Collins germplasm FC708 and multigerm, East Lansing germplasm EL 51. These three lines will be considered for release. There are a number of entries that were significantly more resistant than the worst performing germplasm (20141009) but not as resistant and the most resistant germplasm (FC709-2). These lines will be retested and further selected for resistance to Rcrr and other important sugar beet diseases before a decision to release is made. These results will be accessible to interested parties through the USDA-ARS, NPGS GRIN database (http://www.ars-grin.gov/npgs/index.html).