Integrating viruses into soil food web biogeochemistry.

The soil microbiome is recognized as an essential component of healthy soils. Viruses are also diverse and abundant in soils, but their roles in soil systems remain unclear. Here we argue for the consideration of viruses in soil microbial food webs and describe the impact of viruses on soil biogeochemistry. The soil food web is an intricate series of trophic levels that span from autotrophic microorganisms to plants and animals. Each soil system encompasses contrasting and dynamic physicochemical conditions, with labyrinthine habitats composed of particles. Conditions are prone to shifts in space and time, and this variability can obstruct or facilitate interactions of microorganisms and viruses. Because viruses can infect all domains of life, they must be considered as key regulators of soil food web dynamics and biogeochemical cycling. We highlight future research avenues that will enable a more robust understanding of the roles of viruses in soil function and health.

Evaluation of fungicides to manage rice false smut (Ustilaginoidea virens) in the hills of Nepal.

Rice False Smut (RFS) caused by Ustilaginoidea virens is a major emerging disease of rice due to expanded area of hybrid rice cultivars, increasing use of nitrogenous fertilizers and change in climate. Due to the increasing incidences of this disease across the globe, there is a pressing need to develop techniques for false smut management. The application of fungicides with high efficiency, low toxicity, and low residue is currently the best option to control RFS. Therefore, current research was conducted to determine the effectiveness of fungicides to manage RFS. The experiments were conducted in a completely randomized block design with three replications of seven treatments at RFS-prone subtropical hills of Nepal in the main rice growing season, during 2020 and 2021. The fungicides include trifloxystrobin 25 % + tebuconazole 50 %, chlorothalonil 75 %, carbendazim 12 % + mancozeb 63 %, propiconazole 25 %, azoxystrobin 50 %, carbendazim 50 % and untreated control. Fungicides were applied as two foliar sprays, one at booting and the other at flowering. Fungicide spray significantly increased number of tillers per plant (P ≤ 0.01) and reduced the number of false smut-infected tillers per plant (P ≤ 0.05), false smut severity (P ≤ 0.05), and incidence (P ≤ 0.05). False smut incidence percentages were significantly reduced by all the fungicides except mancozeb + carbendazim compared to the non-treated control. The reduction in RFS incidence was 70 % in propiconazole, 71 % in trifloxystrobin + tebuconazole sprayed plots compared to the non-treated control plots. Thus, the application of suitable fungicide at the appropriate stage would give the satisfactory suppression of RFS in a farmers' field in Nepal.