The multiplication and the migration of cucumber mosaic virus (CMV) were studied in greenhouse conditions in one susceptible ‘Yolo wonder’ and two resistant ‘Milord’ and ‘Vania’ pepper varieties. DAS‐ELISA tests have revealed that the virus is replicated in inoculated leaves of the resistant varieties as high as in the susceptible variety. In the susceptible variety ‘Yolo wonder’, CMV migrated from the leaf lamina to the petiole two days after inoculation and it became systemic three days later regardless the season. In ‘Milord’ the virus migrated from the leaf lamina to the petiole five days after inoculation and it became systemic during the winter 16 days after inoculation. Whereas plants of the same genotype were not infected systemically during the summer. In ‘Vania’, during the two seasons, CMV spread from the blade to the petiole five days after inoculation, but the virus was not detected beyond the inoculated leaf. These results show that ‘Milord’ and ‘Vania’ are resistant to CMV migration. Therefore, the resistance to CMV migration is affected by plant genotype and temperature. The study of effect of pepper plant phenology on infection has revealed that resistance to CMV migration is also affected by the development stage of the plants.

Tomato spotted wilt virus (TSWV) was isolated from pepper, tomato, eggplant, broad bean, lettuce, basil, chrysanthemum, aster, New Guinea impatiens, anemone and gloxinia plants. Virus identification was based on host range, vector transmission, serology and electron microscopy. TSWV was readily detected by ELISA in naturally or artificially infected cultivated or weed plants. The virus was also detected in individual F. occidentalis thrips. The spread of TSWV in vegetable and ornamental plants in greenhouses and/or in the open is related to the close relationship of the virus with the vector.

The spread of cucumber mosaic virus (CMV) was followed during three years in field plots of bell pepper varieties Yolo Wonder (susceptible) and Milord and Vania (partially resistant to CMV movement within plants). During the three test years, CMV spread was delayed 4 to 6 weeks in var. Milord and in var. Vania as compared to var. Yolo Wonder. Final CMV incidence and the apparent infection rate, the latter calculated from Van der Plank logistic analyses, were lower in var. Milord and in var. Vania than in var. Yolo Wonder. The resistance of var. Milord and var. Vania, expressed as a delay of spread and a reduced CMV incidence over the past three years, provides practical disease control.

African eggplant, or garden egg (Solanum aethiopicum) is an important vegetable in most sub-Saharan African countries. Since June 1997, viral symptoms, including mosaic, vein clearing, and stunting, have been observed on several crops of African eggplant cv. Tengeru White at a number of sites in the Arusha region of northern Tanzania. Field inspections revealed disease incidence ranging from 50 to 90%. During the same period, high populations of the green peach aphid Myzus persicae were observed in affected crops of African eggplant. These aphids were also found to reproduce in African eggplants. Flexuous, rodshaped virus-like particles, approximately 750 nm long and 12 nm wide, were found in electron microscope leaf dips from field samples of naturally affected African eggplants. The particle size suggested a species of Potyviridae. Thus, 20 field-infected samples of S. aethiopicum (randomly collected from four farms) were assayed in double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) for the presence of Potato virus Y (PVY) and Pepper veinal mottle virus (PVMV), known to infect tomato and other solanaceous crops in the region (2). However, all samples gave negative results. Further DAS-ELISA were performed with the same extracts from naturally infected plants of S. aethiopicum with antisera directed against Tobacco etch virus, Tobacco vein mottling virus, Pepper mottle virus, and Chilli veinal mottle virus (ChiVMV). All 20 samples were positive only for ChiVMV. ChiVMV, a single-stranded RNA virus transmitted in a nonpersistent manner by several aphid species, is one of the most important viruses of pepper in Asia (1). To confirm DAS-ELISA results, an isolate of ChiVMV from African eggplant was transmitted by mechanical inoculations, resulting in disease on tobacco (Nicotiana tobacco cv. Xanthi nc), pepper (Capsicum annuum cv. Yolo Wonder), tomato (Lycopersicon esculentum cv. Tengeru 97), and African eggplant (S. aethiopicum cv. Tengeru White). Extracts from the inoculated plants tested positive for the presence of ChiVMV in DAS-ELISA. This mechanically transmitted isolate did not infect melon (Cucumis melo), cucumber (C. sativus), or cowpea (Vigna unguiculata), which are nonhosts of ChiVMV. To our knowledge, this is the first report of the natural occurrence of ChiVMV in African eggplant. References: (1) S. K. Green et al. PETRIA 9:332, 1999. (2) R. Nono-Womdim et al. J. S. Afr. Soc. Hort. Sci. 6:41–44, 1996.

SummaryA previous survey on pepper lines (Capsicum annuum L.) indicated that a susceptible cultivar, Yolo Wonder, reacted to cucumber mosaic virus (CMV) by producing a systemic yellow mosaic. By contrast, CMV caused no symptoms on lines Perennial and Vania. The virus is recoverable from the uninoculated leaves of Perennial, while in Vania CMV is restricted to the inoculated leaves. To interpret these phenomena, a comparative study on CMV multiplication rates, yield, specific infectivity and relative proportion of RNAs was made in the inoculated leaves of the three pepper varieties. The rate of CMV multiplication, as estimated by the double antibody sandwich form of enzyme‐linked immu‐nosorbent assay, was lower in Perennial than in Vania or Yolo Wonder. The yield of virus purified from Perennial was very low when compared with Vania or Yolo Wonder. The specific infectivity of the virus extracted from Perennial was less than that from Vania or Yolo Wonder. These results suggest that Perennial is resistant to CMV multiplication, while restriction of the virus in inoculated leaves of Vania is not due to the inhibition of the virus replication. However, polyacrylamide gel electrophoresis revealed that the RNA profiles of CMV purified from the three pepper lines were similar.