Efficacy of bactericides and dormancy-breaking agents on the incidence of fire blight and fruit production of pear in Egypt

摘要

Fire blight has been a serious problem in pear orchards which reaching an epidemic level in most provinces of Egypt starting from 1982 season up tell now. Most of the fire blight infections are blossom blights. A lot of orchards were heavily attacked, so that the control of the disease was necessary. Field experiment trials were conducted in three successive seasons 1997, 1998 and 1999 depends on horticultural practices, which minimize the blossom infection by early flowering, thus making the treeless susceptible to damage by fire blight. On the other hand, bark tissues spray with copper bactericides with different forms in dormancy stage to reduce the amount of inoculum that is available to initiate new infections from cankers. However, bloom sprays with agrimycin, starner and kasugamycin were applied during bloom when weather conditions are favorable for disease. All treatments controlled the disease, but starner was more effective in comparison to untreated pear plants. Screening of rest-breaking agents revealed that mineral oil emulsion at 3%, Thiourea (TU) at 1.5%, urea at 3% and KNO3 at 1.5% combined with Borax at 5 ppm and microelements were effective treatments for enhancing bud burst, early flowering and increasing yield when used at late January of each season.