Investigation on antifungal effects of 7 plant extracts against spore germination of Ophiostoma ulmi and O. novo-ulmi in vitro

Dutch elm disease is one of the most important vascular system diseases of plants in north hemisphere. In this research, Antifungal effects of 7 plant extracts against spore germination of two isolates of causal agents Dutch elm disease, Ophiostoma ulmi and O. novo-ulmi on the Malt Extract Agar 2% (MEA) was studied. For this aim, 2 ml of each plant extract with concentration 0.5gr/ml water was supplemented into each Petri dish containing 18ml MEA 2% (final concentration 0.05gr/ml). The results showed which plant extracts were, significantly (P<0.05 & 0.01), different at antifungal effects against fungal isolates. Also, isolates relatively differed for their susceptibility to plant extracts so that O. novo-ulmi isolate was the more tolerant than O. ulmi isolate and in some cases had statistical significant difference (P<0.05).Totally, results showed that plant extract of Daturea stramonium caused the highest inhibition percent on isolates of O. ulmi and O. novo-ulmi with 67% and 61.75%, respectively. According to this research, plant extracts of Datura stramonium and Allium sativum showed the highest antifungal effects and plant extracts of Mentha piperita and Achillea millefolium had the lowest antifungal effects. Potential using of these plant extracts in order to management of Dutch elm disease has been discussed in this paper.