Sheep Manure as a Potential Source of Tomato Brown Rugose Fruit Virus and Composting as a Mitigation Strategy

Tomato brown rugose fruit virus (ToBRFV) is a tobamovirus posing significant threats to tomato production worldwide because it overcomes the currently deployed genetic resistance. This study investigated a previously undocumented transmission route involving livestock, demonstrating that ToBRFV-infected tomato plant debris fed to sheep can result in the presence of viral RNA in manure and consequential infectivity demonstrated by bioassays. To mitigate this risk, we evaluated composting as an alternative crop residue management strategy. Infected plant debris was composted under controlled aerobic conditions for 60 days, reaching thermophilic temperatures (60-70°C) known to inactivate plant pathogens. Post-composting bioassays on Nicotiana tabacum and tomato seedlings showed no infectivity, despite the presence of residual viral RNA detected by RT-qPCR. These results suggest that composting effectively inactivates ToBRFV. The study highlights composting as a sustainable and scalable approach to virus mitigation, offering an environmentally friendly solution particularly suited in agricultural systems where plant waste is recycled or fed to livestock.