Fusarium solani Root Rot Resistance in Sweet Potatoes

Abstract

Storage roots of 10 sweet potato clones [Ipomoea batatas (L.) Lam.] were screened for resistance to Fusarium solani (Sacc.) Mart, emend. Snyd. and Hans. Clones were inoculated after 0, 6, and 36 days of postharvest storage and incubated in sterile moist chambers for 23 days. Resistance was evaluated by measuring volume of rotted tissue in each clone at the end of the incubation period. Clones tested (in increasing order of average rot volume over three screenings) were: NC 910, NC 925, NC 928, ‘NC Porto Rico 198’, ‘Centennial’, NC 825, NC 835, NC 818, W 125, and ‘Jewel’. Differences among clones for mean rot volume were highly significant within each storage period, and mean rot volumes generally increased in all clones as the length of the preinoculation storage period increased. The average rot volume of roots of resistant clones NC Porto Rico 198, NC 928, NC 910 and NC 925 was 19% that of ‘Jewel’ roots. Correlations between rot volume and postharvest quality factors in comparably stored healthy roots of the same genotypes were too low to be useful selection indices for F. solani resistance.