The activity of some actinomycetes isolates in control of cucumber damping off disease caused by rhizoctiona solani and pythium sp.

الملخص EN

A 28 Actinomycetes isolates which collected from different environmental sources in Basra province were described as Gram positive and are characterized by producing branching hyphae.

Two isolates were identified by molecular analysis of 16 S r RNA gene.

Molecular identification confirmed that two isolates of Actinomycetes from soil had a similarity of 99% with Streptomyces griseus.

The sequence has been deposited at NCBI with Gen bank accession number (NBRC 14886, AB 184627.

1).

While the isolates of date palm roots was analogous to Brevibacterium celere and the sequence of this strain deposited at NCBI with Gen bank accession number (DQ164,K414744601).

The dual culture technique showed that Actinomyces isolates 44 had high antagonistic activity against Rhizoctonia solani as inhibition zone reached 1.7 cm, in contrast to Actinomyces 24 and S.

griseus which revealed a high antagonistic activity against Pythium sp.

with inhibition zone reached 1.2 cm for both isolates.

Pots experiment showed all Actinomyces isolates were significantly reduced cucumber seedling damping off caused by R.

solani and Pythium sp.

the disease incidence for R.

solani damping off were reduced to 1.0% in actinomycetes 44, Actinomycetes 24 and B .celere treatment compared to 11.37 % in control treatment.

Disease incidence at Pythium sp.

damping off was reduced to 1.0% in Actinomycetes isolates compared with that in control treatment (4.33%).

According to this study there is possibility for isolating Actinomycetes isolates which isolated from different environments sources have the ability for reducing cucumber damping off disease caused by R.

solani and Pythium sp.