Seed-borne mycoflora of sesame seeds and their control using salt solution and seed dressing with Dithane M-45

Abstract

Although seed is key in agricultural production, the seed health status of sesame seeds grown in Uganda is largely unkown. Seed health test of 30 seed samples from different parts of Uganda revealed the presence of 12 fungal species, namely, Acremonium sp., Alternaria sesami,A. sesamicola, Bipolaris sp. Cercospora sesami, Corynespora cassiicola, Fusarium equiseti, F. moniliforme, F. pallidoroseum, Macrophomina phaseolina, Myrothesium roridum and Phoma sp. High incidence, 0.3 - 68% of A. sesamicola and 0.3 - 29% of C. sesami were recorded in 29 and 30 seed samples, respectively. The rest of the pathogens occurred in moderate levels, 0.3 - 5% for Acremonium sp., Corynespora cassiicola, A. sesami, F. equiseti, M. phaseolina, F. pallidoroseum, F. moniliforme and Phoma sp. and in trace amounts, 0 - 0.3% for Bipolaris sp. and M. roridum. These pathogens caused seed rot, poor germination and seedling mortality. Two control measures; sorting by salt solution and seed-treatment with Dithane M-45 were used to separate healthy seeds from diseased ones, and kill seed-borne fungi, respectively.

Both sunken and floated seeds had infected and healthy seeds in the samples tested indicating the use of salt solution, was not effective for obtaining healthy seeds in sesame. Seed treatment with Dithane M-45 killed all the mycoflora except A. sesamicola which was detected in 4 out of 14 samples but with a reduced incidence of 0 - 0.5% as opposed to 0-66% in the control. Thus, seed-dressing with Dithane M-45 is recommended for control of sesame seed-borne pathogens.