Suppressing pathogenic fungi associated with stored garlic bulbs causing cloves rot and decreasing disease development during storage by Bacillus subtilis and Trichoderma harzianum

Document Type : Research and Review Papers

Authors

1 Agricultural microbiology Department, Faculty of Agriculture, Sohag university, Sohag, Egypt.

2 plant pathology dept., faculty of agriculture, sohag univ.

Abstract

This study investigated the pathogenic fungi associated with 
stored garlic bulbs causing cloves rot (CR) disease. First, 25 fungal 
isolates were obtained from naturally diseased samples of stored garlic 
bulbs showing cloves rot symptoms collected from different counties of 
Sohag governorate and identified as Aspergillus niger van Tieghem (4 
isolates), Botrytis allii. (4 isolates), F. oxysporum Schlecht. (5 isolates), 
F. proliferatum (Matsush.) Nirenberg (4 isolates), F. solani (Mart.) 
Sacc. (4 isolates), and Penicillium sp. (4 isolates). Ihe pathogenicity test 
conducted on cloves and seedlings under ambient laboratory and 
greenhouse conditions. All isolates belonging to Fusarium spp. were 
superior to other tested fungal isolates, causing the highest infection of 
CR and recovered from infected tissues of garlic cloves. Also, all 
isolates of F. oxysporum caused seedlings' damping-off and were 
superior to other tested isolates of F. solani. Under the greenhouse 
conditions, a significant decline in cloves germination and increased CR 
values of the disease severity index (DSI) occurred on garlic plants 
inoculated with all isolates of F. proliferatum and F. oxysporum. On the 
other hand, all isolates of F. proliferatum and F. oxysporum exhibited 
high values of the DSI after 60 days of bulb storage at room conditions. 
In vitro tests, all tested bacterial and fungal isolates significantly 
inhibited the mycelial growth of F. oxysporum and F. proliferatum. 
However, isolates of T. harzianum were more effective in reducing the 
mycelial growth of both fungi than isolates of B. subtilis. In the 
greenhouse trial, both tested antagonists, B. subtilis (isolate No. 2) and 
T. harzianum (isolate No. 5), significantly increased cloves germination, 
reduced the DSI of cloves rot caused by both fungi, and decreased 
cloves rot disease development of garlic during storage. Under field 
conditions, both tested antagonists significantly increased cloves 
germination and reduced the DSI of cloves rot caused by both fungi, as 
well as decreased the development of garlic cloves rot disease during 
storage under room conditions

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