Frequency of Isolation of Four Fungal Species Colonizing Sorghum Grain Collected from Six Lines in an Anthracnose-Infected Field

Abstract

Sorghum seed mycoflora analysis from six lines grown in an anthracnose infected field was conducted in 2020. Seed samples were collected in July and August, and the frequency of isolation of four grain mold fungi was recorded. In July, seeds collected from SC748 exhibited the highest isolation of Alternaria alternata (40%) while 38% of seeds collected from SC1103-654 and 32% from SC1103-590 also were infected with the pathogen. In August, A. alternata was recovered in 34% of seeds from SC748 and SC265-375. Seeds obtained from RTx430 exhibited the lowest isolation of A. alternata in July and August. In July, Fusarium semitectum was most frequently isolated from BTx623 seeds, followed by SC1103-590 and SC1103-654. Higher recovery of F. semitectum was observed in August, with seeds collected from SC748 exhibiting 55%. In both collection periods, Colletotrichum sublineola was most frequently isolated from anthracnose susceptible lines RTx430 and BTx623 while the resistant SC748 had zero infected seeds. The highest frequency of isolation of Curvularia lunata was recorded from sorghum seeds collected from SC265-375 (20%), followed by SC1103-590 (6%) and 4% from SC748 seeds. This study showed that fungal species once present on the seeds are likely to persist during the growing season at various concentrations. And C. sublineola, causal agent of sorghum anthracnose seemed to be present on/in seeds of susceptible lines, while absent in seeds of the resistant line.