Biological Control of Fire Blight Disease on Pear Caused by Erwinia amylovora in Erbil Province/Iraq

Abstract

Two bacterial strains, Pseudomonas fluorescens L18 and Bacillus subtilis K3 and also five plant extracts Garlic (Allium sativum), Clove (Syzygium aromaticum), Black cumin (Nigella sativa), Thyme (Thymus vulgaris) and Sour pomegranate (Punica granatum) were tested for their efficacy against the fire blight disease of pear caused by the bacterium Erwinia amylovora. The results showed that both bacterial strains had good effect on infected shoots, but the P. fluorescens strain had much better and significant effect than the B. subtilis. This strain protected the shoots by 40% and reduced the disease severity index by 44.2 %, while B. subtilis protected the shoots by 20 % and reduced disease severity by 26 %. The pathogen was affected by all plant extracts but the Garlic extract showed the best effect with (34 mm) inhibition zone and Black cumin that showed the least inhibition zone (10.1 mm). It can be concluded that the investigation of different bacterial strains and herbal extracts can be concerned for control of this disease in future.