Receptor

Inoculation

Pathogenic fungus

Fungus

Bacteria

Biology

Microbiology

Germination

Biological pest control

Horticulture

Microorganism

Antagonism

Pathogenic bacteria

Fusarium oxysporum

Botany

Genetics

Biochemistry

The antagonistic effect of the antagonistic soil microorganisms B. subtilis, Ch. horrida, F. semitectum, Ph. humcola and T. viride on the growth and the pathogenic ability of C. echinulata, F. oxysporum, R. bataticola and R. solani that cause seed and root rot was studied. 145 organisms were isolated of which 128 isolates were fungi belonging to 24 fungi genera and 17 bacterial isolates belonging to 6 bacterial genera from four places namely: Jeddah , Makkah Al-Mukarramah , Taif and Al-Qunfudhah. Antagonism was studied between the soil antagonistic microorganisms and the pathogenic fungi in the laboratory. The pathogenesis was tested on two plants using the Emerald variety of okra and Eskandarani variety of vegetable marrow. C. echinulata was found to be the most harmful to the two plants followed by R. bataticola and then F. oxysporum. It was found in the case of dual cultures in PDA medium that the antagonistic soil microorganisms has an inhibiting effect on the growth of the pathogenic fungi especially T. viride .When the media is inoculated with either an antagonistic microorganisms or a pathogenic fungus the effect is the inhibition of the other organism grown on the surface of the inoculated media. When the soil is mixed with a filtrate of an antagonistic microorganisms previously exposed while to boiling temperature, no inhibition to the growth of the pathogenic fungi takes place, the non-boiled filtrates had an inhibiting effect on the pathogenic fungi particularly Ps. aeruginosa bacteria on C. echinulata, and F. oxysporum fungi. It was also noted that the non-boiled filtrates of more than one antagonistic microorganisms had an inhibiting effect on the growth the former fungi especially F. semitectum on C. echinulata . Ph. humicola ,Ch. horrida and F. semitectum fungi showed a high secretive activity on the chitinase enzyme. the study of employing the soil antagonistic microorganisms as a resistance means against disease showed that the addition of the antagonistic microorganisms to a soil previously inoculated with an equal amount of the pathogenic fungus for two days reduced the rate of disease and increased the rate of germination especially when used in the case of Ph. humcola against R.solani in okra and F. semitectum against F. oxysporum in vegetable marrow. When the antagonistic microorganisms are added to the inoculum of pathogenic fungi at the same microorganisms are added to the inoculum of pathogenic fungi at the same time, this led to a reduction in the rate of disease and increased germination, especially when Ph. humicola is used. In the case of okra the affected fungus was variety F.oxysporum and in the case of vegetable marrow it was R. solani. Soaking Azmerly of kidney beans in non-boiled filtrates of soil antagonistic microorganisms and growing them in test tubes led to the reduction of the disease rate by the two pathogenic fungi C. echinulata and F. oxysporum

Biological control of soil-borne pathogenic fungi in seed and root diseases in western region in Saudi Arabia