Temporal and spatial progress of the diseases caused by the crinivirus tomato chlorosis virus and the begomovirus tomato severe rugose virus in tomatoes in Brazil

Abstract

Efficient management of whitefly‐borne diseases remains a challenge due to the lack of a comprehensive understanding of their epidemiology, particularly of the diseases tomato golden mosaic and tomato yellowing. Here, by monitoring 16 plots in four commercial fields, the temporal and spatial distribution of these two diseases were studied in tomato fields in Brazil. In the experimental plots these diseases were caused by tomato severe rugose virus (ToSRV) and tomato chlorosis virus (ToCV), respectively. The incidence of each virus was similar in the plots within a field but varied greatly among fields. Plants with symptoms for both diseases were randomly distributed in three of four spatial analyses. The curves representing the progress of both diseases were similar and contained small fluctuations, indicating that the spread of both viruses was similar under field conditions. In transmission experiments of ToSRV and ToCV by Bemisia tabaci MEAM1 (former biotype B), these viruses had a similar transmission rate in single or mixed infections. It was then shown that primary and secondary spread of ToCV were not efficiently controlled by insecticide applications. Finally, in a typical monomolecular model of disease progress, simulation of the primary dissemination of ToSRV and ToCV showed that infected plants were predominantly randomly distributed. It is concluded that, although the manner of vector transmission differs between ToSRV (persistent) and ToCV (semipersistent), the main dispersal mechanisms are most probably similar for these two diseases: primary spread is the predominant mechanism, and epidemics of these diseases have been caused by several influxes of viruliferous whiteflies.

Lack of synergistic effects in tomato plants co‐infected with tomato severe rugose virus and tomato chlorosis virus

“…As begomoviruses and criniviruses are transmitted by the same vector B. tabaci, although by different routes, an increase in the concentration of one or both viruses may result in an increase in the rate of transmission by the vector, as found by Cuellar et al (2015) in a study of the interaction between sweepoviruses and the crinivirus SPCSV in sweet potato plants. The transmission rate does not seem to be affected by ToSRV and ToCV in doubly infected tomato plants, as reported by Macedo et al (2019). The transmission rate of ToCV and ToSRV was the same when the viruses were acquired by B. tabaci MEAM1 from single-or co-infected tomato plants.…”

“…The transmission rate does not seem to be affected by ToSRV and ToCV in doubly infected tomato plants, as reported by Macedo et al . (). The transmission rate of ToCV and ToSRV was the same when the viruses were acquired by B. tabaci MEAM1 from single‐ or co‐infected tomato plants.…”

“…Therefore, management alternatives for golden mosaic, caused by ToSRV, and tomato yellowing, caused by ToCV, should be adopted to minimize damage to tomato crops, as recommended by Macedo et al . ().…”

“…Although no significant synergistic effect was found between ToSRV and ToCV in tomato plants, both viruses, either in single or in mixed infections, significantly affected plant development, which may result in quantitative and qualitative reductions in yield. Therefore, management alternatives for golden mosaic, caused by ToSRV, and tomato yellowing, caused by ToCV, should be adopted to minimize damage to tomato crops, as recommended by Macedo et al (2019).…”

Tomato chlorosis virus, an emergent plant virus still expanding its geographical and host ranges

“…In Spain, for example, ToCV prevalence in tomato crops is reported to be very high, frequently at levels of 50–100% (Fortes et al , ; Lozano et al , ; Velasco et al , ). Field investigations conducted in Brazil on tomato have shown that the main dispersal mechanism of the disease caused by ToCV is primary spread, with epidemics being caused by successive influxes of viruliferous whiteflies (Macedo et al , ).…”