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THE SUPPRESSION effect of four biocontrol agents (i.e., cyanobacteria extracts: Nostoc linckia, Anabaena variabilis, Oscillatoria agardhii, and Spirulina sp.), in combination with Rhizobium leguminosarum biovar viceae (TAL–1148), against Rhizoctonia solani in faba bean plants was investigated through laboratory and pot experiments. After testing five R. solani isolates for pathogenicity, all of the identified fungi were found to be pathogenic and to have induced symptoms of root rot and pre- and post-damping-off. Comparing the results of in vitro experiments to the untreated control, algal extracts dramatically suppressed the pathogen's ability to develop mycelially. In comparison to the control (0%), O. agardhii showed the highest reduction (59.63%), followed by N. linckia (51.85%), A. variabilis (48.52%), and Spirulina sp. (40.37%). When compared to the other studied cyanobacteria and the control treatment, the combined effect of Rhizobium and cyanobacteria extracts (O. agardhii and N. linckia) produced the highest reduction in pre- and post-emergence damping-off, measuring 13.33 and 6.67%, respectively, in pot studies. Furthermore, in comparison to the control, these treatments enhanced the number and dry weight of nodules, shoot height, dry weight of shoots, N2%, and N content. Similar results were obtained using the fungicide Rizolex-T50%, which decreased the incidence and severity of the disease but had negative effects on Rhizobium and the symbiotic N2–fixing characteristics. Plants cultivated from treated faba bean seeds showed notable increases in the activity of the oxidative reductive enzymes (i.e., peroxidase and polyphenol oxidase). Thus, it could be concluded that using algal extracts in conjunction with R. leguminosarum was thought to be a practical, secure, and economical way to manage this type of soil-borne disease. More further studies are needed to emphasize this sustainable and eco-friendly approach using different phytopathogens. [ABSTRACT FROM AUTHOR]

The utilization of Trichoderma longibrachiatum filtrate as a safe biocontrol method for producing zinc nanoparticles is a promising approach for managing pests and diseases in agricultural crops. The identification of Trichoderma sp. was achieved through PCR amplification and sequencing of 18s as ON203115, while the synthesis of ZnO-NPs was accomplished by employing Trichoderma filtration. The presence of ZnO-NPs was confirmed by observing a color change to dark green, along with the use of visible and UV spectrophotometers, and the formation and chemical structure of ZnO-NPs were examined. Direct exposure to ZnO-NPs exhibited a significant inhibitory effect on the growth of Fusarium oxysporum at 80.73% compared with control. Also, the percent mortality of Meloidogyne incognita second juveniles stage (J2s) results showed 11.82%, 37.63%, 40.86%, and 89.65% after 6, 12, 24, and 72 h, respectively in vitro. Disease resistance was assessed in the greenhouse against M. incognita and F. oxysporum using the drench application of ZnO-NPs. The application of ZnO-NPs significantly reduced the disease severity of F. oxysporum and improved the quality and quantity of sweet pepper yield. In addition, the application of ZnO-NPs to M. incognita resulted in a significant reduction in the number of nematode galls, egg masses per root, eggs/egg mass, and females by 98%, 99%, 99.9%, and 95.5% respectively. Furthermore, it was observed that the application of ZnO-NPs to pepper plants not only inhibited the growth of F. oxysporum and M. incognita, but also promoted the recovery of pepper plants as indicated by improvements in stem length by 106%, root length 102%, fresh weight 112%, root fresh weight 107%, and leaf area 118% compared to healthy control plants. Additionally, real-time PCR application and DD-PCR technique revealed that the application of ZnO-NPs stimulated the secretion of certain enzymes. These findings suggest that the biosynthesized ZnO-NPs possess anti-nematode and antifungal properties, making them effective for protecting plants against M. incognita and F. oxysporum invasion in soil. This study significantly contributes to our understanding of the nematicidal and fungicidal activities of ZnO-NPs in suppressing soil-borne diseases. [ABSTRACT FROM AUTHOR]