Effect of Organic and Inorganic Salts on the Development of Helminthosporium solani, the Causal Agent of Potato Silver Scurf

Abstract

Potato silver scurf, caused by Helminthosporium solani, is an important postharvest disease of economic significance. Control of H. solani has been accomplished primarily by postharvest applications of thiabendazole. However, many strains of H. solani have become resistant to thiabendazole, resulting in failure of disease control. Consequently, alternative control strategies are needed. This study showed that several salts significantly reduced silver scurf development on potato tuber at a concentration of 0.2 M and that the timing of application also influenced salt efficacy. Among the 23 tested salts, aluminum chloride was the only one reducing silver scurf severity when applied either 2, 4, or 7 days after H. solani inoculation. Aluminum lactate, potassium sorbate, sodium carbonate, sodium metabisulfite, and trisodium phosphate also markedly reduced silver scurf severity but only when applied 2 or 4 days after inoculation. Ammonium acetate, calcium chloride, sodium benzoate, sodium citrate, and sodium formate reduced disease severity by at least 50% when applied 2 days after H. solani inoculation. With the exception of calcium chloride and sodium formate, these salts also were shown to strongly inhibit H. solani mycelial growth or spore germination in vitro. Results of this study further demonstrate the possibility of using selected salts for the control of potato silver scurf.

Comparative Efficacy of Potassium Salts Against Soil-borne and Air-borne Fungi and Their Ability to Suppress Tomato Wilt and Fruit Rots

“…On the other hand, one pathogen could be inhibited by various salts. These results are consistent with many other reports [17,27,[70][71][72]. In fact, these salts possess wide-spectrum antimicrobial properties and have been demonstrated to inhibit the growth of several fungal pathogens infecting stored fruits, vegetables, and ornamental species [17,[19][20][21][22].…”

Salts Application for Suppressing Potato Early Blight Disease

“…Recent studies suggest that salt application reduces postharvest potato diseases. Olivier et al (1998) and Hervieux et al (2002) showed that application of potassium sorbate, calcium propionate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and ammonium bicarbonate at 0.2 M reduced silver scurf lesion development and Helminthosporium solani sporulation on inoculated and naturally infected potato tubers. These reports confirm the obtained results in the present study showing that sodium bicarbonate was found to be strongly inhibiting to mycelial growth of A. solani at concentrations of 20 and 30 mg/ml either under in vitro or in vivo trails.…”

Helminthosporium velutinum and H. aquaticum sp. nov. from aquatic habitats in Yunnan Province, China

“…In addition to Helminthosporium velutinum and H. aquaticum in Helminthosporium sensu stricto, we included the isolates of H. solani with the sequence data available in GenBank. Helminthosporium solani is an important plant pathogen that causes silver scurf disease on potato, resulting in a cosmetic surface blemish to the tubers, and weight loss in storage (Firman & Allen 1995, Olivier et al 1998, Hervieux et al 2002. Helminthosporium aquaticum is close to H. velutinum in morphology and DNA sequence data (Fig.…”