The Role of Non‐Vectored Soil Transmission as a Primary Source of Infection by Pepper Mild Mottle and Cucumber Mosaic Viruses in Glasshouse‐Grown Capsicum in Australia

Abstract

Virus disease limit glasshouse production of capsicums in the Supraysia District of New South Wales. Symptoms develop on plants about 4 weeks after planting; and up to 83° of plants are infected. The major virus is cucumber mosaic (CMV) with some pepper mild niottle (PMMV) also present. Evidence is presented to show that the primary source of intection of both viruses is most likely to be debris from previous crops remaining in the soil. It demonstrates a previously unconsi‐dered mechanism tor survival and spread of labile viruses such as CMV and the ecological ecological consequence of these results are considerable.

Differentiation of Biologically Distinct Cucumber Mosaic Virus Isolates by PAGE of Double-Stranded RNA

“…One Sunraysia capsi cum isolate (CP 91 91/370) had a slightly larger RNA 2 (2.99 kb as compared with 2.91) and was placed in type C. Capsicum isolates from the Sydney metropolitan area (type E) had much smaller RNA I than the Sunraysia capsicum isolates (3.05 kb as compared with 3.24) and an RNA 2 larger than the Sunraysia isolates and the same as CP 91/370. It is not surprising that the isolates from Sunraysia differ from those in the Sydney metropolitan area, as they appear to be biologically different [17], While only three capsicum samples of CMV from the Sydney metropolitan area have been obtained, it would appear isolates may be split into two groups (E and F), differing in RNA 3. Such variation could be expected, as there would be a greater variety of infection sources in Sydney than in Sunraysia plantings.…”

Tomato Mosaic Virus Infection in a Recirculating Nutrient Solution

“…Because (a) viruses are an important limiting factor in soil grown crops that are also grown using hydroponics, (b) the use of hydroponics is increasmg and (c) we were already looking at the role of water in transmission of some viruses (PARES and GUNN 1989) we designed experiments to investigate transmission of viruses in a recirculating hydroponic system. These experiments are the subject of this paper.…”

Discrimination between tobamoviruses and their pathotypes for L-gene-mediated resistance in green pepper (Capsicum annuum L.) by reverse transcription-polymerase chain reaction

“…Once the viruses are carried into fields with seeds, they spread quickly to healthy plants by mechanical transmission through cultivation and natural contact of the plants with the systemically infected plants grown from the infested seeds (Broadbent 1976). The viruses remain in the soil even after cultivation and serve as a primary source of infection in the next cultivation (Pares and Gunn 1989). Because we have no effective measures to prevent contact or soil transmission of tobamoviruses, the control of tobamoviruses in green pepper largely depends on detection and elimination of contaminated seeds before cultivation as well as use of resistant cultivars.…”