Kimberly sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2020

Authors: Eujayl, Imad; Strausbaugh, Carl

Submitted to: Plant Disease Management Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2021
Publication Date: 8/16/2021
Citation: Eujayl, I.A., Strausbaugh, C.A. 2021. Kimberly sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2020. Plant Disease Management Reports. 15:V161.

Interpretive Summary: Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV), is an important viral disease problem worldwide, leading to significant yield loss in both the field and storage. Preventing rot and sucrose losses in storage is important to the economic viability of the sugar beet industry. The primary means of controlling these problems is through host resistance. Thus, eight Beta vulgaris germplasm lines from the USDA-ARS Kimberly sugar beet program and five check cultivars were screened to characterize them for both resistance to BNYVV and storability. Four entries had resistance to fungal rots in storage, but only the KDH19-17 entry had a root rating similar to the resistant checks. The KEMS12-FP17 entry had both resistance to fungal rots and a good rhizomania foliar rating which has also been true in two previous evaluations. Thus, some entries will serve as genetic sources for identifying additional resistance to BNYVV and storage rots, which will aid the sugar beet industry in improving sucrose yield and retention in commercial sugar beet cultivars.

Technical Abstract: Rhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet germplasm lines with resistance to BNYVV and storage rots, eight Beta vulgaris lines and five check cultivars were screened. The lines were grown in a sugar beet field infested with BNYVV during the 2020 growing season in a randomized complete block design with 6 replications. At harvest on 13-14 October, roots were dug and evaluated for rhizomania symptoms and then placed in an indoor commercial sugar beet storage building. After 131 days in storage, samples were evaluated for the percentage of root surface area covered by fungal growth or rot. Rhizomania symptom development in the field was uniform and other disease problems were not evident in the plot area. The BNYVV susceptible sugar and red beet checks both had 100% foliar symptoms and a high root disease severity ratings. The resistant check with two resistance genes, Rz1 + Rz2 (check 3), had 1% foliar symptoms and low root rating. The resistant checks with only one resistance gene had foliar symptoms ranging from 8 to 13%, but their root ratings were still within an acceptable range. Foliar symptoms indicate single gene resistance for BNYVV is becoming marginal. Based on the root ratings, all entries had some level of BNYVV resistance since they were all better than the susceptible checks. However, only entry 9 had a root rating similar to the resistant checks and the yellowish leaves (100% foliar rating) were likely an indication of nutrient deficiency and not RZ susceptibility. Four entries (1, 4, 9, and 10) had resistance to fungal rots in storage. Entry 1 has also had no foliar symptoms and a good storage rating in two previous evaluations. Entry 4 should be evaluated again next year since it had no foliar symptoms and a good storage rating. Some entries may serve as a starting point for identifying additional sources of resistance to BNYVV and storage rots.