OCCURRENCE OF SOIL SUPPRESSIVENESS TO FUSARIUM-WILT DISEASE OF BROAD BEAN IN ISMAILIA GOVERNORATE

Fusarium oxysporum wilt of broad bean was studied in nonsuppressive an d suppressive soil. One hundred and fifty soil samples were collected from 10 cultivated and reclaimed fields. The disease response of the 1 0 fields showed great variation. Percentages of diseased plants ranged from 19 to 85%. Soil samples collected from field Fm2 (soil No. 6, su ppressive) showed the lowest percentage of diseased plant (19%), while all other soils showed not less than 40% of diseased plants. When the 10 field soil samples were inoculated with F. oxysporum they exhibite d a high receptivity value (over 50% diseased plants) while Fm2 soil s howed almost the least value (less than 10% diseased plants). The fung al flora of the soil samples was studied where 64 spp. belonging to 37 genera were recovered. While the lowest number was recorded in soil P k1 (soil No. 2, nonsuppressive) the highest total and species counts w as found in Fm2 soil. Chemical analysis revealed that chloride and cal cium ions were higher in Fm2 soil. The number of chloride ions was hig her than calcium ions in all samples. Sugar cane bagasse, an organic s upplement, and autoclaving enhanced the wilt disease development and r etarded the suppressiveness of Fm2 soil.