Disinfection Efficacy of Tobamovirus-Contaminated Soil in Greenhouse-Grown Crops

Abstract

The tobamoviruses tomato brown rugose fruit virus (ToBRFV) and cucumber green mottle mosaic virus (CGMMV) have caused severe crop damages worldwide. Soil‐mediated dispersion of the mechanically transmitted tobamoviruses constitute a major hindrance toward mitigating disease spread in crops carefully planted under sanitized conditions. Tobamoviruses are viable for months in soil and plant debris and for more than a year adhere to clay. However, a low percentage of infectious foci occur in soil following a tobamovirus‐infected growing cycle, rendering disinfection studies of several contaminated plots inconclusive for large‐scale crop productions. We have therefore formulated a rigorous platform for studying disinfectant efficacy in greenhouses by pouring a virus inoculum to planting pits prior to disinfectant treatment and by truncating seedling roots before planting, which was otherwise conducted under sanitized conditions. We have found that chlorine‐based Taharan was significantly efficient in preventing disease spread of ToBRFV and CGMMV in tomato and cucumber plants, respectively. KlorBack was often as good as Taharan. In addition, a formulation of chlorinated tri‐sodium phosphate used at a nonphytotoxic 3% concentration showed disinfection efficiency similar to Taharan effect on ToBRFV infection only. Our study provided a small‐scale platform for disinfectant efficacy evaluation necessary for application in tobamovirus‐contaminated soil, which commonly occurs in commercial tomato and cucumber green-houses.