Effect of time and storage temperature on survival ofverticillium dahliae microsclerotia in dried potato stem tissue

Verticillium wilt (Vw) is a widespread and significant disease of potato (Solatium tuberosum). It is caused by the soil-borne fungiVerticillium dahliae andVerticillium albo-atrum. Host plant resistance is a promising method of Vw control. Culture-based methods that quantify the pathogen in host stem tissue are often used for Vw resistance screening. Either stem sap or dried stem tissue can be plated to measure pathogen populations in stems of plants that have been exposed to the pathogen. This study evaluated the effect of storage time and temperature on the survival ofV. dahliae microsclerotia in dried stem tissue. In both years of the study, the number of colony forming units (cfu) in stem samples did not change dramatically for the first six months in storage, regardless of storage temperature (-80 C, -20 C, 4 C, 23 C). After that, cfu means decreased sharply at all temperatures. Long-term survival of microsclerotia was lowest in samples stored at room temperature. These data indicate that stem samples can be stored for processing for several months. If processing is to occur after that, then samples should be stored at 4C.