Sweet potato seedling test for resistance to leaf scab disease (Elsinoe batatas)

Authors

  • Nicole E.J.M. Smit Tongan-German Plant Protection Project (G. T.Z.), PO Box 881, Nuku'alofa, Kingdom of Tonga, South Pacific
  • Tevita Holo Plant Protection Section, Vaini Research Station, Ministry of Agriculture, Fisheries and Forests, Kingdom of Tonga, South Pacific
  • Jill E. Wilson Department of Agronomy and Soil Science College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, Honolulu, Hawaii, USA

Keywords:

Sweet potato, Ipomoea batatas, Leaf scab disease, Scab disease, Elsinoe batatas, Seedling test, Disease resistance

Abstract

A technique was developed for rapidly testing sweet potato seedlings for resistance to leaf scab disease (Elsinoe batatas). Since E. batatas isolates can differ in virulence and aggressiveness, inoculum was derived from field-grown sweet potato vines of different cultivars by incubating stem and petiole sections of heavily-infected cuttings for two days in Petri dishes. A breeding-derived population of seedlings inoculated with a suspension of 3-4 × 103 spores ml-1 could be divided into three groups, heavily infected (43%), moderately infected (36%) and not-infected (21%) seedlings. A field trial showed that 76% of clones derived from not-infected and moderately infected seedlings remained scab-resistant under natural leaf scab epidemics. Of clones derived from heavily infected seedlings, 75% showed susceptible reactions in the field. The test is accurate enough to be used in a breeding programme for scab resistance in sweet potato.

Issue

Section

Research Papers