The crinivirus Tomato chlorosis virus (ToCV) is often found infecting tomato crops in Brazil, with variable incidence, but associated with prevalence of its primary vector, Bemisia tabaci MEAM1. ToCV control is difficult because there are no resistant commercial tomato varieties or hybrids available and chemical spray for control of the whitefly vector has not been effective. The present study evaluated the partial host range of a Brazilian isolate of ToCV and the preference of B. tabaci MEAM1 for oviposition on those species identified as susceptible to the virus. Subsequently, transmission tests were performed using plants of each ToCV host species as sources of inoculum to elucidate the epidemiological importance of nontomato sources of inoculum for infection of tomato. Among 80 species experimentally inoculated, 25 were susceptible, including 6 previously not known to be hosts (Jaltomata procumbens, Physalis pruinosa, Solanum aculeatissimum, S. viarum, Beta vulgaris var. cicla, and Chenopodium quinoa). Preference of whitefly for oviposition and infection by ToCV under free-choice transmission tests varied among the susceptible species. When ToCV-infected tomato, eggplant, and C. quinoa were used separately as sources of inoculum for virus transmission to tomato plants, mean percentages of infected plants were 76.6, 3, and 0%, respectively. Average oviposition of Bemisia tabaci on these three hosts were 2.7, 10.6, and 0.0 eggs/cm², respectively. Additional studies will be necessary to evaluate the importance of ToCV host plants under field conditions and their efficiency as sources of inoculum for virus acquisition and transmission to tomato crops.

Physalis peruviana is being incorporated into small fruit’s scene in Brazil. It can be found in local markets, mainly in the cities of São Paulo and Rio de Janeiro, but has still been imported, since Brazilian production is small (Rodrigues et al., 2009). Typical symptoms of orthotospovirus, including chlorotic spots and concentric rings on the leaves were observed on P. peruviana (Fig 1) in two different crop seasons, March-October 2016 and March-October 2017, in an experimental area located in the campus of the University of São Paulo (USP), Piracicaba, state of São Paulo. Each experimental area was composed of 126 plants. For both years, leaf extracts from 30 randomly chosen field plants were tested in plate-trapped antigen - enzyme linked immunosorbent assay (PTA-ELISA), using specific antiserum against the nucleocapsid protein of Groundnut ringspot virus (GRSV). The antiserum was kindly provided by Dr. Alice K. Inoue-Nagata, Embrapa, CNPH, DF, Brazil. Serological results showed an increase of virus i...

This collaborative work by over 180 researchers from 40+ countries addresses the challenges posed by “phantom agents”—putative pathogenic agents named in literature without supporting data on their existence. Those agents remain on regulatory lists, creating barriers in trade and plant certification. Historically identified based solely on symptoms, these agents lack isolates or sequence data, making reliable detection or risk assessment impossible. After reviewing over 120 such agents across 10 key plant genera, we recommend their removal from regulatory lists and call for revised standards aligned with modern diagnostics. This effort seeks to streamline germplasm exchange, benefiting global agriculture by removing the constraints imposed by phantoms.

Despite an economy based mostly on agriculture, literature on viral diseases of plants is scarce in Paraguay. Only recently, researches on plant viruses took an impulse resulting in a precise identification of many of them affecting plants either cultivated or not. To provide reliable information regarding plant viruses present in Paraguay, an annotated list of them was prepared, covering descriptions from 1920 to present day. There have been some important outbreaks with severe yield losses in crops as cucurbits, citrus, sesame, bean, maize, peanuts and tomato. Many of older descriptions are included for their historical significance, but most identifications made require confirmation. On the other hand, recent descriptions have been completed, based on several assays, especially molecular characterization. This list is organized alphabetically following scientific names of the plant species found naturally infected by viruses, with comments about symptoms, geographical distribution, incidence, identification procedures, and other information, with due literature references. It is based on a compilation of publications made on plant virus diseases in Paraguay. Described virus species, in a total of 38 recognized by ICTV, belonging to 17 different genera (Alphaendornavirus, Ampelovirus, Begomovirus, Benyvirus, Carlavirus, Cilevirus, Closterovirus, Comovirus, Cucumovirus, Dichorhavirus, Fabavirus, Luteovirus, Ophiovirus, Orthotospovirus, Potexvirus, Potyvirus and Tobamovirus), besides two unclassified, and four unidentified. There is also a case of viroid described in Citrus spp. Infections caused by potyviruses are the most numerous. These viruses were described in more than 40 plant species, belonging to 18 botanical families. Because of crop diversity and richness in native flora, many more viruses must be present in Paraguay, which future works will certainly reveal, especially with the increase in manpower involving researches, especially cooperative with foreign centers, on plant viruses, which has been very limited until now. Also, knowledge on existing viruses may have relevance in understanding their epidemiology and provide the basis for their control strategies and quarantine measures, to avoid new variants of existing viruses or new viruses being introduced.