Effectiveness of disinfectants against the spread of tobamoviruses: Tomato brown rugose fruit virus and Cucumber green mottle mosaic virus

Abstract

Background: Tobamoviruses, including tomato brown rugose fruit virus (ToBRFV) on tomato and pepper, and cucumber green mottle mosaic virus (CGMMV) on cucumber and watermelon, have caused many disease outbreaks around the world in recent years. With seed-borne, mechanical transmission and resistant breaking traits, tobamoviruses pose serious threat to vegetable production worldwide. With the absence of a commercial resistant cultivar, growers are encouraged to take preventative measures to manage those highly contagious viral diseases. However, there is no information available on which disinfectants are effective to deactivate the virus infectivity on contaminated hands, tools and equipment for these emerging tobamoviruses. The purpose of this study was to evaluate a collection of 16 chemical disinfectants for their effectiveness against mechanical transmission of two emerging tobamoviruses, ToBRFV and CGMMV.

Methods: Bioassay was used to evaluate the efficacy of each disinfectant based on virus infectivity remaining in a prepared virus inoculum after three short exposure times (10 s, 30 s and 60 s) to the disinfectant and inoculated mechanically on three respective test plants (ToBRFV on tomato and CGMMV on watermelon). Percent infection of plants was measured through symptom observation on the test plants and the presence of the virus was confirmed through an enzyme-linked immunosorbent assay with appropriate antibodies. Statistical analysis was performed using one-way ANOVA based on data collected from three independent experiments.

Results: Through comparative analysis of percent infection of test plants, a similar trend of efficacy among 16 disinfectants was observed between the two pathosystems. Four common disinfectants with broad spectrum activities against two different tobamoviruses were identified. Those effective disinfectants with 90-100% efficacy against both tobamoviruses were 0.5% Lactoferrin, 2% Virocid, and 10% Clorox, plus 2% Virkon against CGMMV and 3% Virkon against ToBRFV. In addition, SP2700 generated a significant effect against CGMMV, but poorly against ToBRFV.

Conclusion: Identification of common disinfectants against ToBRFV and CGMMV, two emerging tobamoviruses in two different pathosystems suggest their potential broader effects against other tobamoviruses or even other viruses.

Keywords: CGMMV; Disease control; Disinfectants; ToBRFV; Tobamovirus; Tomato and watermelon.

Fig. 1

Assessing the effectiveness of various disinfectants against ToBRFV through visual symptom observation. Treated tomato plants were visually compared 3–4 weeks post inoculation against the untreated ToBRFV control (ToBRFV). a Mock: buffer treated control, b 10% Clorox, c 2% Virkon, d 2% Virocid, e 2% Virex, f 0.5% Lactoferrin, g 2.4% SP2700, h 10% NFD Milk, and i 2% Kleengrow

Fig. 2

Effectiveness of disinfectants against the mechanical transmission of ToBRFV on tomato. Statistical analysis using one-way ANOVA was followed by Dunnett’s multiple comparisons (α = 0.05) test to analyze the level of significance between the ToBRFV control and the treatments. ns (not significant): adjusted p-value > 0.05. Significant treatments are designated with different number of asterisks based on the level of significance, **adjusted p-value ≤ 0.001, ***adjusted p-value ≤ 0.0001 and ****adjusted p-value ≤ 0.00001 ". ‘EUC’ represents ethanol/urea/citric acid; ‘TSP’ represents Trisodium phosphate. Y-axis represents the mean percent infection and x-axis the treatments

Fig. 3

Assessment of disinfectant efficacy against the mechanical transmission of CGMMV on watermelon. Statistical analysis using one-way ANOVA was followed by Dunnett’s multiple comparisons (α = 0.05) test to analyze the level of significance between the CGMMV control and the treatments. ns (not significant): adjusted p-value > 0.05. Significant treatments are designated with different number of asterisks based on the level of significance, **adjusted p-value ≤ 0.001, ***adjusted p-value ≤ 0.0001 and ****adjusted p-value ≤ 0.00001 ". ‘EUC’ represents ethanol/urea/citric acid; ‘TSP’ represents Trisodium phosphate. Y-axis represents the mean percent infection and x-axis the treatments

Fig. 4

Comparative effectiveness of selected disinfectants upon different application rate against ToBRFV. The chart depicts ToBRFV infectivity remained after the treatment of disinfectants at different application rate of a SP 2700, b Virocid, c Clorox, d Virkon, e Virex, f Lactoferrin, within a short exposure time (< 60 s) on tomato “Moneymaker” plants. The effect of various concentrations of disinfectants on tomato plants against ToBRFV infection is represented with symptom expression in photo panels: g (0.1% Lactoferrin), h (0.5% Lactoferrin), i (2% Virkon), j (3% Virkon), k (5% Clorox), l (10% Clorox), m (positive ToBRFV control) and n (uninfected healthy control)

Fig. 5

Comparative effectiveness of selected disinfectants in different application rates against CGMMV infectivity. The chart depicts CGMMV infectivity remained after treatment of disinfectants at different application rate. a Clorox, b SP 2700, c Lactoferrin, and d Virocid within a short exposure time (> 60 s) on watermelon “Sugarbaby” plants. The effects from various concentrations of disinfectants on watermelon plants against CGMMV infection are shown with symptom expression on the test plants and confirmation test by ELISA, e (Mock, non-inoculated healthy control), f (CGMMV positive control without treatment), g (2.4% SP2700), h (2% Virocid), i (10% Clorox), and j (0.5% Lactoferrin)