Biological and Physical Control Measures to Manage White Rot Disease Incidence in Onion and Garlic under Natural Field Conditions

Abstract

White rot caused by the soil borne fungus Stromatinia cepivora (Berk.) Whetzel, is the most destructive disease affecting onion (Allium cepa L.) and garlic (Allium sativum L.) crops in Egypt and worldwide. Therefore, the present investigation aimed to evaluate the efficacy of soil solarization alone or integrated with bio-control agents, in controlling white rot disease incidence in onion and garlic crops as well as their resulting yield. The data obtained revealed significant reduction and increase in yield for garlic and onion crops when cultivated using treated seeds or transplants with biocontrol agents, followed by planting in solarized soil and subsequent cultivation in solarized soil alone. The garlic bulb-seeds immersed in growth suspension of P. oxalicum; B. pumilus followed by B. subtilis revealed the lowest disease incidence. Meanwhile, high records of disease incidence were recorded in un-solarized soil. Furthermore, the treatment of bio-agents combined with soil solarization resulted in a significant increase in garlic bulb yield compared with plants grown in un-solarized soil. Onion plants showed similar results concerning disease incidence and harvested yield. The current study aims to utilize the hot weather months in Egypt to apply soil mulching technique for controlling serious soilborne plant pathogens. This can be done either alone or in conjunction with biological agents as part of an integrated pest management program.