Some studies on potato common scab disease. Pathological studies

Three streptomyces isolates causing potato common scab disease [i.e., S1, S2 and S3] were successfully isolated and identified from the growing areas at Menia. Pathogenicity tests, either in the laboratory or pots, revealed that potato cultivars Alpha, Diamont and Spunta could be infected by all three S. scabies isolates. The tested isolates caused lesions on the root tips of radish, software, soybean, squash, tomato, turnip and wheat seedlings. Only isolate S2 induced lesion on the root tips of cowpea, Nicotiana glutinosa, and sunflower seedlings. None of the S. scabies isolates infected maize seedlings or storage roots of carrot and sweet potato. However, storage roots of radish were infected by the highly pathogenic isolate S2. S. Scabies isolates produced phytotoxic substances with most produced after five days at 25C

Sensitivity of fusarium moniliforme, F. oxysporum and F. salani to superoxide anion and hydrogen peroxide in vitro

The sensitivity of three Fusarium species [i.eFusarium moniliforme Sheldon, F. oxysporum Schlecht. and FSolani [Mort.] Sacc.] to a superoxide anion [O2-] producing system and to hydrogen peroxide [H2Op] differed with species and stage of growth Conidial germination, sporulation and mycelial growth were more sensitive to the O2-producing system or H202, respectively, in FOxysporum, F moniliforme and FSolaniThe least sensitive to O2-or H2O2 were conidial germination in F. moniliforme, sporulation in FSolani and mycelial growth in F Oxysporum The inhibitory effects of O2-increased with increasing riboflavin concentration and H202 increased with increasing H2O2 concentrationAlso, the viability of conidiospores, particularly F. moniliforme and F. oxysporum from 7-day old illuminated cultures, was decreased by O2-treatment However, possible application of O2-producing system[s] or H2O2 as antifungal for use in soil-borne plant diseases control was discussed