In Poland in 2002 and 2005 two different isolates of Pepino mosaic virus signed PepMV-SW and PepMV-PK were obtained. Both isolates were compared on the basis of their symptomatology on a series of plant species. In addition, the isolates were characterized by the nucleotide sequence analysis of the triple gene block, coat protein and a part of the polymerase genes. The studies showed that the Polish isolates differ from each other and belong to two strains. PepMV-SW was highly similar to European isolates, showing extensive sequence identity, ca.

At the beginning of 1999, a new virus disease occurred in protected tomato crops in The Netherlands. Initial diagnostic tests revealed the presence of a potexvirus but serological tests ruled out the presence of Potato X potexvirus (PVX). Tests for other potexviruses reported from solanaceous crops provisionally identified the virus as Pepino mosaic potexvirus (PepMV). The virus was purified, and an antiserum was produced, which showed strong reactions with both the type isolate of PepMV from pepino and two other isolates from tomato. Host range and symptomatology of the pepino and tomato isolates of PepMV revealed clear differences from PVX. However, differences were also observed between the pepino and tomato isolates of PepMV. Sequence alignment of DNA fragments of 584 bp derived from the RNA polymerase cistron showed almost 95% identity with the pepino isolate, whereas the identity with PVX appeared to be < 60%. Together, these results identified PepMV as the causal agent of the new virus disease in tomato. Based on the differences from the type isolate from pepino (Solanum muricatum), the isolates from tomato should be considered as a distinct strain of PepMV for which the name tomato strain is proposed.

Pepino mosaic virus (PepMV) has recently emerged as a highly infectious viral pathogen in tomato crops. Greenhouse trials were conducted under conditions similar to commercial tomato production. These trials examined whether tomato plants can be protected against PepMV by a preceding infection with an attenuated isolate of this virus. Two potential attenuated isolates that displayed mild leaf symptoms were selected from field isolates. Two PepMV isolates that displayed severe leaf symptoms were also selected from field isolates to challenge the attenuated isolates. The isolates with aggressive symptoms were found to reduce bulk yields by 8 and 24% in single infections, respectively. Yield losses were reduced to a 0-3% loss in plants that were treated with either one of the attenuated isolates, while no effects were observed on the quality of the fruits. After the challenge infection, virus accumulation levels and symptom severity of the isolates with aggressive symptoms were also reduced by cross-protection. Infection with the attenuated isolates alone did neither affect bulk yield, nor quality of the harvested tomato fruits.

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ReferaatReinigings-en ontsmettingsmiddelen worden toegevoegd om leidingen in substraatsystemen te reinigen. Deze producten kunnen potentieel groeiremming veroorzaken. Onderzocht is welke toetsmethode in aanmerking komt (effect, reproduceerbaarheid, duur en kosten van de proef) om groeiremming aan te tonen. De phytotox testmethode bleek hiervoor het meest geschikt. Vervolgens zijn enkele chloorproducten, reinigingsmiddelen, waterstofperoxiden en ozon nader onderzocht in concentraties zoals in de praktijk gebruikelijk en zonodig lager om groeiremming te verhinderen. Chloorbleekloog en reinigingsmiddelen veroorzaken zelfs bij lage concentraties groeiremming. Het moet voorkomen worden dat deze producten in het recirculerende water terecht komen.Ontsmettingsproducten geven geen groeiremming als de concentratie lager is dan de geadviseerde dosering.Ozon geeft geen groeiremming, maar ook geen groei stimulatie. Binnen het project is steekproefsgewijs een aantal producten getoetst. In de toekomst kan op aanvraag een product worden getoetst. Er is niet onderzocht of betreffende producten hun geclaimde werking hebben.