Isolation and Molecular Characterization of The Pathogens Trichoderma harzianum and Pseudomonas tolaasii on the Edible Mushroom Agaricus bisporus and Evaluation of Some Desert Plant Extracts for Control Them

Abstract

Seven isolates of Pseudomonas bacteria were isolated from the casing soil and 11 fungal isolates from mushroom farm residues in the mushroom production farm - College of Agriculture , Tikrit University. According to the pathogenicity test, the highest infection rate was recorded by the bacterial isolate 1077, It was diagnosed to the species level as Pseudomonas tolaasii according to the nucleotide sequence of the 16S rRNA gene. It was registered globally in the NCBI website within the accession number MW085029.1, this record is the first for this bacteria in Iraq, while the fungal isolate 1076 showed the highest pathogenicity and this isolate was diagnosed phenotypically to the level of the genus Trichoderma and diagnosed to the level of species T. harzianum according to the nucleotide sequences of the 5.8S rRNA gene and registered globally in the NCBI website within the accession number MW147763.1. In studying the effect of treatments of alcoholic extracts of Atriplex tatarica and Haloxylon salicornicum and their powder in the presence of the pathogenic fungus T. harzianum (Th) and the pathogenic bacteria P. tolaasii (P.t) on the morphological characteristics, infection rate, productivity and quality of mushroom Agaricus bisporus, the results showed that the pathogens had no effect on the most of the morphological characteristics, while the treatment (A. tatarica and H.salicornicum extracts 4 mg/ml + P. tolaasii + T. harzianum) was the best treatment that increased the productivity of the A. bisporus, reduced the severity and rate of infection, and improved of some qualitative characteristics.