عزل و تشخيص الفطريات Rhizoctonia solani و Fusarium oxysporum المسببة لأمراض الجذور و قواعد سيقان نبات عين البزون) (Cartharanthus roseus في بعض المشاتل ومكافحتها احيائياً و كيميائياً

Isolation and identification of the fungi Rhizoctonia solani and Fusarium oxysporum that cause diseases of the roots and bases of the stems of periwinkle plants (Cartharanthus roseus) in some nurseries and their biological and chemical control

Abstract

This study was conducted at the College of Agriculture – University of Karbala with the aim of isolating and diagnosing the fungi that cause root rot and seedling death of Cartharanthus roseas plant in a number of nurseries in the provinces of Karbala and Babylon and test their pathogenicity، and test the antagonistic ability of a number of biological factors، chemical pesticides، salicylic acid and chitosan in combating the most pathogenic fungi. And the cause of root rot and seedling death of Cartharanthus roseas plant in the laboratory and under the conditions of the greenhouse .
The results showed that 30 isolates of Rhizoctonia spp. and 11 isolates of Fusarium spp. and 2 isolates of the fungus Macrophomina phaseolina. And one isolate of Alternaria spp. It was diagnosed phenotypically and the results of pathological ability in the laboratory showed the superiority of isolates FB11، RB29، RK22، RK4، RK2 significantly in reducing the germination of red radish seeds on W.A medium with a germination percentage of 0.00% in all of them، and isolate( RK22 )Rhizoctonia solani was superior in inhibiting the germination of Baston seeds in the same sample. In the plastic pots under the conditions of the greenhouse، the percentage of germination was 0.0% .
The results of the phenotypic diagnosis of the most pathogenic RK22 showed that it belongs to the fungus Rhizoctonia solani، while the results of the molecular diagnosis of isolate FB11 showed by analyzing the sequences of the nitrogenous bases of the doubling DNA products by polymerase chain reaction (PCR-amylified products) for the selected genetic markers and using the BLAST program (Basic Local Alignment Search Tool) This isolate، which was isolated from the roots of the Cartharanthus roseas plant، is Fusarium oxysporum (FB11) .
The results of testing the antagonistic ability of the biological agent Trichoderma koningiopsis on PDA culture media showed that it achieved an inhibition rate of 100% and 88.63%، respectively، for the fungi Fusarium oxysporum (FB11) and Rhizoctonia solani (RK22) .
While the bacteria Azotobacter chroococcum achieved an inhibition rate of 96.26% and 93.46%، respectively for the fungi Fusarium oxysporum (FB11) and Rhizoctonia solani (RK22) respectively .
The chemical pesticides Beltanol، Bastan، Metchazol and Tabsen achieved an inhibition rate of 100% for both Rhizoctonia solani and Fusarium oxysporum and for all concentrations used on PDA culture media، while the percentage of inhibition when using the recommended concentration of the biocide Verox was 44.40% and 33.30%، respectively. For the fungi Fusarium oxysporum and Rhizoctonia solani .
The results of the test of the antagonistic ability of chitosan at concentrations of 2، 1، 0.5 g / l showed that the concentration of 2 g / l was significantly (P > 0.05) by achieving the inhibition rate of the fungi Rhizoctonia solani and Fusarium oxysporum amounted to 77.77 %، 34.81% .
While the laboratory results of using salicylic acid at concentrations of 1.5، 1، and 0.5 g/L showed that the concentration of 1.5 g/L was significantly (P > 0.05) superior in its inhibition of pathogenic fungi، as the percentage of inhibition of pathogenic fungi Rhizoctonia solani and Fusarium oxysporum، respectively، was 65.13 %. 31.83% .
The results showed the response of both local and imported cultivars to infection with the fungus Rhizoctonia solani and Fusarium oxysporum، as the percentage of inhibition was 100% for both cultivars with Rhizoctonia solani، while the percentage of inhibition when using the fungus Fusarium oxysporum was 80% and 86.66%، respectively for the local and imported cultivars .
The treatment of integration between Azotobacter chroococcum + Trichoderma koningiopsis + Fusarium oxysporum (FB11 + Tr + Az) and Azotobacter chroococcum + Trichoderma koningiopsis + (Rhizoctonia solani RK22 + Tr + Az) was superior in reducing the percentage and severity of plastic house infestation by 33% and 5.3% under plastic house conditions. %، 21.33 %، 7.00%، respectively، compared to the pathogenic fungi treatment alone، which amounted to 100.00%، 84.00%، 100.00%، and 100.00%، respectively، for the two pathogenic fungi Fusarium oxysporum and Rhizoctonia solani. It was 24 cm، 8.36 g، 2.00 g، 0.70 g. 0.20 g، respectively، for FB11 + Tr + Az treatment and 21.33 cm، 6.73، 1.23 g، 0.55 g، 0.08 g for RK22 + Tr + Az treatment، compared to the treatment of the pathogenic fungi F.oxysporum and R.solani، which reached 5.36 cm، 3.00 g، respectively. 0.10 g، 0.03 g، 0.001 g for F.oxysporum alone and 0.00 for all growth parameters in the treatment of R.solani.