Effect of Viruses UMV, UVC, PapMV-U, and PLRV on Ulluco Production and Their Control

Eight viruses infect ulluco (Ullucus tuberosus Caldus), an Andean tuber crop. Three of them, potato leafroll virus (PLRV), Andean potato latent virus, and potato virus T, also infect potato (Solanum tuberosum L.). Arracacha virus A and papaya mosaic virus, ulluco isolate (PapMV-U) infect other crops. PLRV, one of the most damaging potato viruses, was detected in healthy potato plants growing in the field next to PLRV-infected ulluco plants, indicating that viruses can be disseminated among different Andean tuber crops under natural conditions. The viruses with the highest incidence were PapMV-U and three others, ullucus virus C, ullucus mild mottle virus, and ullucus mosaic virus. In two field experiments in Junín, Peru, ulluco plants of accession MH290 infected with ullucus virus C or ullucus mosaic virus, and ulluco plants of native variety Jaspeado infected with PLRV or PapMV-U yielded about 30% less than the healthy control plants. Also, during field exposures, only a low percentage of healthy plants were reinfected with viruses. These results indicate that the production and use of virus-free ulluco seed tubers is justified in this environment and, therefore, the use of better seed by farmers has been promoted, particularly in the La Libertad community in Junín, Huancayo Department.