Onion plant were attacked by neck rot disease caused by Botrytis allii (Munn). The modern trends were directed to study the effect of various natural substance against neck rot disease. The effect of plant extract and essintal oil on the incidence of plant disease was studied. Plant extracts of six plant extracts, clove (Dianthus caryophyllus), cinnamam (Cinnamomum zeylamicum), thyme (Thymus vulgaris L.) fenugreek (Trigonella, fonicum), amme (Ammi visnagal), black pepper (Piper nigrum) and three oil essential gernium (Pelargonium gravedens), black cumin seeds (Nigella sativa L.)  and blue gum (Eucalyptus globulus).                 The six plant extracts and the three oil essential were evaluated as  antifungal substance on the mycelial growth and incidence and disease severity of neck rot disease. The antifungal proprieties of cloves extract was more effective than black pepper then Fenugreek extract on inhibiting mycelial and disease, incidence, while amme, thyme cinnamam showed the lowest effect. On the other hand oil essential of geranium was more effective than blue gum and oil black cummon seeds on  inhibiting mycelial growth and disease incidence.