Decontamination treatment against Tilletia indica
Studies have been carried out in USA on the efficacy of hot water and sodium hypochlorite treatments to eliminate teliospores of Tilletia indica (EPPO A1 quarantine pest), in order to decontaminate storage and handling equipment. The germinability of teliospores of Tilletia indica, either suspended in water, on the surface of healthy seeds or within the unruptured sori of infected seeds was assessed after hot water and sodium hypochlorite treatments (alone or in combination). Temperatures of 25, 60 and 80 °C, NaOCl concentrations (wt/vol, pH 11.5) of 0, 0.53 and 1.60 %, and immersion periods of 1, 5, 15 and 30 min were evaluated. Results showed firstly that hot water (80 °C) kills nearly all teliospores of T. indica after 1 min of contact (even inside unruptured sori), secondly that the addition of NaOCl to water kills more free teliospores than hot water alone, and finally that when NaOCl is applied the appearance of teliospores is altered (bleached colour, spore wall and sheath greatly expanded) which provides a persistent indication that they have been treated. For example, an application of 1.60% of NaOCl at 25 °C for 5 min followed by a 10-min delay before the seeds were rinsed in fresh water killed free teliospores but not all teliospores within sori. As teliospores within the sori of infected seeds are partially protected, the authors recommend that seeds should be removed as much as possible from the storage and handling equipment before the treatment. However, they felt that a combination of hot water and NaOCl treatments (followed by a rinse with fresh water to reduce corrosion damage) could be a useful tool for decontamination of storage and handling equipment, but not for commodity treatment as it would be too harsh for wheat seeds.
Sources
Smilanick, J.L. Hershberger, W.; Bonde, M.R.; Nester, S.E. (1997) Germinability of teliospores of Tilletia indica after hot water and sodium hypochlorite treatments.
Plant Disease, 81(8), 932-935.