Among the main diseases associated to potatoes in South of Chile are soft rot and black leg, both caused by the bacteria Erwinia spp. The main source of dissemination of this pathogen is the potato seed tuber. In arder to diagnose the incidence of this dlseases in the X Region of Chile, a survey was carried out with the lollowing objetives:
- To identily the causal agent of black leg and of latent infection in seed tubers, used in comercial seed plants.
- To assess and determine the quantitative potential of latent infection.
During the survey, several comercial patato seed lots were visited recording the number of plants showing black leg symptoms. At harvest, patato tubers of some of the seed lots were colected, to assess potential of latent inlection using laboratory test. In both cases the causal agent was isolated using a specific culture media, biochemical and pathogenicity test. As a result of this study it was concluded that most of the seed lots surveyed are within the Iimits of tolerances imposed by the regulations of the certilication seed law for potatos and, in this case, lar black leg. These are 0,3% for prebasic seed category and 0,5% for basic seed. The potential of latent infection, varied from 40% to 100% after the test, for prebasic and basic seed, respectively. It implyies that a high number of seed tubers carry the bacteria. The main causal agent isolated was the bacteria identified as Erwinia carotovora ssp atroseptica. |
ChileanJAR
