Selection of Sweet Potato Plants with Internal Cork Virus that Produce Symptomless Roots. L. W. Nielsen, Professor Emeritus, Department of Plant Pathology, North Carolina State University, Raleigh, NC 27650. Plant Dis. 65:489-491. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-489.

A stock of susceptible Porto Rico sweet potato infected with the internal cork virus (ICV) was propagated 10 yr and evaluated annually for internal necrosis (cork) in roots cured and stored at 25 C for 6 mo. The percentage of roots with symptoms declined from 93 to 50% in the 10 yr. Plants from this stock consistently produced fewer roots that developed internal necrosis than did plants from roots with symptoms. Plants propagated from symptomless roots had internal necrosis in 20% or less of the harvested roots. Scions from symptomless roots graft-inoculated to virus-free Porto Rico plants transmitted internal cork virus to the new crop of roots. The symptomless-carrier reaction of infected Porto Rico is assumed to have arisen from mutation.

Keyword(s): Ipomoea batatas.