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The study aimed to isolate and diagnose fungi contaminating onion fruits and secreting mycotoxins, and to study the effect of Moringa oleifera extract on the growth of the fungus Aspergillus niger. The results of isolating fungi from onions showed the presence of the following fungi: Aspergillus niger, Fusarium sp., and Rhizopus stolonifer. It became clear that there was a predominance of the fungus A. niger, then the fungus Fusarium sp., followed by the fungus Rhizopus stolonifur, as their frequency rates reached 53.33, 36.66, and 10.00%, respectively, while the occurrence rate reached 83.33, 50.00, and 33.33%, respectively. In this study, molecular diagnosis of the fungus A. niger was carried out using internal transcribed spacer (ITS) genetic markers, and the results of chemical analysis using thin layer chromatography (TLC) showed that 9 of the 16 isolates were A. niger, isolated from onions, produced ochratoxin A with a production rate of 56.25%. The moringa extract inhibited the growth of the fungus A. niger, as the percentage of inhibition increased with increasing concentration, and the highest percentage of inhibition was at a concentration of 15%, which reached 47.32%. The percentage of inhibition was at concentrations of 5 and 10 (12.82 and 26.15%). [ABSTRACT FROM AUTHOR]

Rhizoctonia solani, the causal agent of stem canker and black scurf disease on potato is a real threat to potato crop with up to 50% yield reduction. Current study was carried out to determine the effect of some Trichoderma isolates with different types of soil on the above diseases under laboratory and glasshouse conditions. Eight non-pathogenic strains of Trichoderma were isolated from potato roots and surrounding soil and examined for antagonism of Rhizoctonia diseases. Results showed that strains T. hamatum T8 and T. harzianum T5 had great potential as biocontrol agents for inhibiting the pathogen growth in dual culture and culture filtrate methods. The effect of different types of soils on the radial growth of R. solani AG-3PT in plates showed that Dorrigo soil inhibited the pathogen growth in laboratory by 68% as the colony diameter of pathogen recorded 2.8 cm which exceeds other soil types. While most Trichoderma strains that isolated from this area had a potential of protecting potatoes from the infection by the pathogen and acted as a biocontrol agent. Applying non-pathogenic Trichoderma isolates was the best method when inoculated the soil of pots with conidial suspensions which promote the growth of potato plants. T. harzianum (T5), T. hamatum (T6) and T. hamatum (T8) strains were eliminated stem canker and black scurf disease and improved potato plant growth in glasshouse experiment. The outcome of current study indicated the potential for utilizing Australian Trichoderma strains to reduce Rhizoctonia diseases on potato plants and increase productivity. [ABSTRACT FROM AUTHOR]

This study looked at the effects of biological control strategies for root and stem rot disease caused by Rhizoctonia solani using soil organisms as biocontrol agents. The results of the field survey showed the spread of root and stem rot disease on broad bean plants in some areas of Najaf Governorate, where the infection rate ranged from 32- to 89.5%. The Isolation process showed that five fungal isolates of Rhizoctonia solani were associated with the disease, which differed in some phenotypic characteristics in terms of growth speed and color difference. The results of the molecular diagnosis using the ITS marker sequencing for the three most pathogenic isolates showed that they were belonging to Rhizoctonia solani, thus were named Ahmed 1, 3, 4 and registered in the GenBank under accession numbers; ON 394595.1, ON 394597.1, and ON 394599.1, respectively. In the pathogenicity test, R. solani isolates displayed a difference in their virulence on broad bean plants, where R. solani 1 (Al-Mashkhab isolate) was the most virulent among the isolates and was selected for subsequent studies. Isolate T. longibrachiatum (T3) showed high antagonistic efficiency against isolate of the pathogenic fungus R. solani on P.D.A culture media, gave the highest inhibitory percentage 75.06% compared to isolates T1 and T2 of Trichoderma harzianum, which led to inhibition of the pathogen to 68.71% and 68.94%, respectively. In the culture filtrate test of isolates of the living fungi, isolate T3 had the highest inhibition in the growth of pathogenic R. solani, which was 5.20 cm compared to the two live fungi T1 and T2, which led to 6.20 and 5.95 cm, respectively. As for the pots experiment, the results revealed that the isolate of T. longibrachiatum (T3) protected the broad beans plants from root and stem rot pathogen, where the disease was not seen compared to the treatment of the pathogenic fungus R. solani, only in which the infection severity was 80%. [ABSTRACT FROM AUTHOR]