Josefina C. Nayga and Ruben M. Gapasin
Sweet potato plants inoculated with scab at 2 and 4 weeks after planting (WAP) were severely infected as shown by deformation of leaves and stunted plant growth. Scab infection also caused early death of main vines. However, this was not observed in plants inoculated at 6 and 8 WAP.
Significant differences in disease severity ratings, leaf area and number and weight of marketable roots were observed among the different treatments but not in fresh vine weight, and number and weight of non-marketable roots. Total root yield of plants inoculated with scab at 2 and 4 WAP was reduced relative to the control by 27.8% and 24.5%, respectively. Eight-week old inoculated plants had a yield reduction of only 4.4%.
Keywords: VSP-1. Sweet potato. Stem and foliage scab (Sphacelorna batatas Saw.). Disease severity ratings.
Annals of Tropical Research 8(3):(1986)