A b s t r a c t A r t i c l e I n f oPenicillium expansum (Link) is one of the most important postharvest pathogens of stored pear fruit worldwide. It causes blue mold rot, a decay that can lead to significant economic losses during storage, which can also impact fruit destined for processing due to the production of carcinogenic mycotoxin patulin and citrinin. In the present study, microbial antagonist of Trichoderma harzianum have been isolated from mushroom compost and tested for antagonistic properties against P. expansum. Assays of biological control of P. expansum on pear fruits were carried out under cold storage condition artificially, by two different methods of inoculation. Significant differences (p<0.0001) were obtained in reducing the lesion diameters of blue mould on wounded pear fruits inoculated artificially either by Dipping or spray with T. harzianum in comparison with the control treatment. There were also significant differences between mean depth of infection in dipping treatment compared to spay method and control, whereas no significant differences were appeared between depth of infection in spray treatment compared to control. Furthermore, results obtained in this study demonstrated that T. harzianum would be an interesting microorganism to be used as a biocontrol agent and could be considered as one of the most promising alternatives for postharvest control of P. expansum. Therefore, integration of T. harzianum by artificially inoculation was effective and might be a safe strategy to control P. expansum infection in pear fruit, and will definitely become an internationally adopted practice.

This study includes storage operation for two local Pear varieties, Harmé Naska and Harmé Lasoore. For collecting the local pear varieties, Mawet and Sitak in Sulaymaniyah-Iraq were visited during 2015. Selected pear trees were 15-18 years aged. From Mawet the local pear variety named Harmé Naska, and from Sitak the local pear variety, Harmé Lasoore, were collected, where both varieties were grafted on (Harmé Sheena) local pear trees. Fruits were picked on 15 th and 16 th October 2015. Fresh fruits without any deformation and injury were randomly selected for the study and transported to the laboratory at Kirkuk in net boxes. Fruits were selected randomly almost uniformed and not deformed, keeping in mind freshness, injure free, bearer kept on, then transported to Kirkuk in net boxes then wiped gently before refrigerating. Fruits were stored in laboratories of Agriculture College-Kirkuk University in two refrigerators, with the temperature of 5°C and 3°C respectively. The refrigerators were loaded with pears for 30, 60 and 90 days. Some pears were also kept on benches at ambient temperature. Depending on four sources of electric power to keep the refrigerators working 24 hrs a day. The following qualities that have been taken for the fruits: weight, total soluble solids and firmness.