Reference Report for IND20374373
| Title: | Fusaria and other fungi on soybean seedlings and roots of older plants and interrelationships among fungi, symptoms, and soil characteristics. |
| Authors: | Killebrew, J.F., Roy, K.W., Abney, T.S. |
| Source: | Can. J. Plant Pathol. 1993, 15(3):139-146 |
| Abstract: | Soyabean seedlings and rhizosphere soil were collected from 45 soyabean fields in Mississippi, USA. Seedling roots and shoots were assayed for mycoflora and rated for disease symptoms. Selected fungus, seedling and soil variables were analysed for possible correlations. Thirty-eight fungal taxa, including 8 species of Fusarium, were isolated from seedlings. F. oxysporum, Rhizoctonia solani, F. solani form B, Macrophomina phaseolina and Trichoderma viride were the most frequent isolates from roots; Alternaria alternata, Phomopsis longicolla, Phoma spp. and Epicoccum nigrum the most frequent from shoots. Fusaria predominated on seedlings, especially on roots, where they accounted for 35% of fungal isolates. Number of seedlings (stand) in the field was negatively correlated with root and hypocotyl disease indices. Frequency of isolation of F. solani form B from roots was negatively correlated with stand and positively correlated with root and hypocotyl disease indices, seedling age and soil pH. Some correlations suggested that prior colonization of roots by certain fungi predisposed aerial tissues to other fungi. Other correlations suggested coinvasion of roots by F. solani form B and R. solani and by F. oxysporum and M. phaseolina. In greenhouse pathogenicity tests, F. solani form B and R. solani were pathogenic to seedlings; F. oxysporum and F. acuminatum [Gibberella acuminata] were not. Soyabean roots from fields in Arkansas, Illinois, Indiana, Kentucky and Mississippi were assayed to determine the incidence and geographic distribution of F. solani form B in roots of older plants (growth stages R5 and R7). F. solani form B occurred with high frequency in roots and was widely distributed geographically |
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