Biological Control of the Potato Tubers Dry Rot Caused by Fusarium roseum var. sambucinum under Greenhouse, Field and Storage Conditions using Bacillus spp. Isolates

Selected isolates of Bacillus spp. fromsalty soils were evaluated for their ability to suppress a dry rot disease on potato tubers caused by Fusarium roseum var. sambucinum. Greenhouse trials undertaken in pots demonstrated that bacterial antagonists stimulated the emergence of potato tubers. Evaluation of yield parameters showed the efficiency of isolates I32 of B. licheniformis and X16 of B. cereus to reduce disease severity. Field experiments showed that the isolate X16 of B. cereus seems to be the most effective to control Fusarium rot on seed tubers and increase yield parameters. The seed tuber colonization by bacteria increased until 61 days after planting with a rate significantly higher for B. cereus X16 (2 103 CFU/cm2). After 75 days, it decreased for all the treatments applied. Moreover, traditional and cold storage assays run during 6 and 8 months respectively, showed that dry rot incidence was significantly lower in potato boxes treated with each antagonist alone or by the mixture (X16 + B. thuringiensis var. galleriae 55T and Trichoderma viride + 55T) as compared with pathogen inoculated control boxes and to those treated with the fungicide carbendazim