DETECTION, IDENTIFICATION AND MANAGEMENT OF SEED-BORNE FUNGAL PATHOGENS ON FARMER SAVED SEEDS OF SOYBEAN (Glycine max (L.) Merrill)
ABSTRACT:
Seed-borne fungal pathogens on farmer-saved seeds of soybeans was investigated by examine a total of eleven (11) seed samples from two districts (Saboba and Yendi) in the Northern region and one from CSIR-Savanna Agricultural Research Institute (CSIR-SARI). Visual examination of the seed samples revealed the main categories of damaged seeds as shriveled (ranging from 6% to 10.5%), discolored (8.3% to 12.5%), broken and cracked (5.5% to 12.5%). Seed sample obtained from Sunsong-Gbung in the Yendi district revealed the highest discolored seeds (12.5%). The highest broken and cracked seeds were revealed on seed samples obtained from Zang (12.5%). The blotter and agar plate incubation methods as described by ISTA, 2007; Mathur and Kongsdal, 2003 were used to detect and identify fungi that were associated with the seed samples. A total of nine fungi including four that have been recorded as pathogenic on soybean were recorded with their corresponding ranges; Cercospora spp. (9.0% to 11.9%), Alternaria spp. (9.0% to 14.2%), Fusarium spp. (9.8% to 15.2%) and Macrophomina phaseolina (7.8% to 13.4%). Five saprophytic fungi species; Aspergillus flavus (9.0% to 12.9%), Aspergillus niger (7.0% to 13.5%), Penicillium spp. (9.0% to 14.1%), Curvularia spp. (9.0% to 13.2%) and Rhizopus stolonifer (16.9% to 21.5%) were observed to be associated with the seed samples. The use of Insector T 45, Monceren GT 390 FS, Garlic extract and Neem seed extract as seed treatments over a period of 90 days, revealed a decrease in fungal prevalence as well as an increase in seed germination and seedling vigour compared with the untreated seeds. Seeds treated with Monceren GT 390 FS over a period of 90 days revealed the highest fungal reduction as well as high germination (85.0%) and seedling vigour (1360.1). Pathogenicity tests conducted on four fungal isolates; Microphomina phaseolina, Cercospora spp., Aternaria spp., Fusarium spp. to fulfil Koch’s postulate proved to be positive. All soybean plants inoculated with fungal isolates developed disease symptoms one week after inoculation. Re-isolation of fungal pathogens from diseased plants confirmed they were the causal organism of the symptoms that were observed. Farmers should be encourage to practice seed treatment prior to storage to protect their seeds from infection by fungi pathogens.
DETECTION, IDENTIFICATION AND MANAGEMENT OF SEED-BORNE FUNGAL PATHOGENS ON FARMER SAVED SEEDS OF SOYBEAN (Glycine max (L.) Merrill)