Turf-type tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.: TTTF] is a predominant turfgrass species for lawns throughout cool-humid regions, yet brown patch (caused by Rhizoctonia and Rhizoctonia-like species) can cause severe damage during the summer months. Hypothesized strategies to help minimize brown patch severity and decrease fungicide use includes establishing TTTFs with a high level of host resistance and minimizing summer nitrogen (N) applications. A two-year field study was conducted in West Lafayette, IN to determine the influence of late-spring and summer applied N at two application rates among five TTTF cultivars. Urea-N was applied monthly at two rates from April to July, totaling to 73.5 and 245.0 kg N ha-1. Turf performance was determined using visual ratings for turf quality, relative canopy greenness, disease severity (0-100%), and seasonal brown patch as calculated by area under the disease progress curve (AUDPC). Brown patch was generally not affected by N-rate for any cultivar in either study year. While none of the TTTF cultivars had complete brown patch resistance, cultivar differences were observed, with disease severity ranging from 9.8 to 39.0% and 20.0-51.9% in 2021 and 2022, respectively. Selecting a brown patch resistant cultivar reduced seasonal brown patch severity by 61% across study years compared to the most susceptible cultivars. This study demonstrates that summer N applications to TTTF lawns should not be completely avoided to reduce brown patch as previously suggested and emphasizes the importance of host resistance for disease management.

Background Soil-borne plant diseases represent a severe problem that negatively impacts the production of food crops. Actinobacteria play a vital role in biocontrolling soil-borne fungi. Aim and objectives The target of the present study is to test the antagonistic activity of chitinase-producing Streptomyces cellulosae Actino 48 (accession number, MT573878) against Rhizoctonia solani. Subsequently, maximization of Actino 48 production using different fermentation processes in a stirred tank bioreactor. Finally, preparation of bio-friendly formulations prepared from the culture broth of Actino 48 using talc powder (TP) and bentonite in a natural as well as nano forms as carriers. Meanwhile, investigating their activities in reducing the damping-off and root rot diseases of peanut plants, infected by R. solani under greenhouse conditions. Results Actino 48 was found to be the most significant antagonistic isolate strain at p <= 0.05 and showed the highest inhibition percentage of fungal mycelium growth, which reached 97%. The results of scanning electron microscope (SEM) images analysis showed a large reduction in R. solani mycelia mass. Additionally, many aberrations changes and fungal hypha damages were found. Batch fermentation No. 2, which was performed using agitation speed of 200 rpm, achieved high chitinase activity of 0.1163 U mL- 1 min- 1 with a yield coefficient of 0.004 U mL- 1 min- 1 chitinase activity/g chitin. Nano-talc formulation of Actino 48 had more a significant effect compared to the other formulations in reducing percentages of damping-off and root rot diseases that equal to 19.05% and 4.76% with reduction percentages of 60% and 80%, respectively. The healthy survival percentage of peanut plants recorded 76.19%. Furthermore, the nano-talc formulation of Actino 48 was sufficient in increasing the dry weight of the peanut plants shoot, root systems, and the total number of peanut pods with increasing percentages of 47.62%, 55.62%, and 38.07%, respectively. Conclusion The bio-friendly formulations of actinobacteria resulting from this investigation may play an active role in managing soil-borne diseases.