Verticillium Wilt on Rose Plants in Minia Governorate and its Control

Nine isolates of Verticillium dahliae, (VD1 -VD9) were isolated from roots and stems of wilted rose plants (1-2 years old) grown in Minia and Abo-Qurqas counties, Minia Governorate during summer, 2012. All isolates were able to induce wilt symptoms with different degrees of vascular discoloration on rose plants through 60 - 90 days after planting. The maximum percentages (100%) of wilted plants were obtained due to using isolates VD1, VD2 and VD3 which were isolated from Minia county, followed by isolate VD8which was isolated from Abo Qurqas county (91.7%). All tested concentrations of Rizolex-T and Topsin-M decreased the linear growth of the four tested isolates. The fungitoxic effect was increased with increasing the fungicide concentration up to 400 ppm; that inhibited completely the growth of the tested fungi. Phos-root X and Formula X-1 stimulated the growth of the four tested isolates at the lowest rates, whereas the highest level, 3 ml/l, decreased the growth than control. Two bioagents, i.e., T. viride and B. subtilis were able to inhibit the mycelial growth of all tested pathogenic isolates. B. subtilis was effective in reducing the growth of the tested isolates where it gave 64.8 and 85.9% inhibition comparing to T. viride. The tested fungicides with different concentrations reduced significantly the percentage of infected plants comparing with control. Rizolex- T was more effective than Topsin-M in their efficiency. The maximum reduction of Verticillium wilt disease was recorded with using 3 ml/l of Phos-Root X and 2ml/l of Formula-X. Addition of the two tested bio agents one week before planting to soil significantly decreased the percentages of infected rose plants and disease severity under artificial infection with any of the tested isolates of Verticillium dahliae.