Pepino mosaic virus
| What is it and why the concern? |
Click on the image to view the symptoms in more detail |
Pepino mosaic virus (PepMV) is highly contagious and has a significant potential to cause damage in protected tomato production. Yield losses have not been quantified but evidence suggests that significant crop losses are possible if action is not taken to eliminate infection. There is also a risk to other solanaceous crops especially potato but this risk has yet to be quantified. The virus is readily spread via contaminated tools, human hands or clothing, and by direct plant-to-plant contact. It can also be transmitted by grafting or when taking cuttings from infected mother plants. Limited evidence suggests that the virus replicates better at higher temperatures.  Tomato plant infected with PepMV showing extensive
mosaic symptoms on leaves (photograph courtesy of K. Hamilton). |
Infected plant with nettle-like head (photograph courtesy of K. Hamilton) 
|
 Click on the image to view the symptoms in more detail |
|
 Click on the image to view the symptoms in more detail |
On ripened fruit there are distinctive lighter areas
giving a marbled appearance. Experience from The Netherlands indicates
that severe symptoms occur early in the season (Dec - Feb) or late
in the season (August onwards). Between these times, symptoms may
disappear or appear only as a few yellow spots on leaves.Affected fruit showing typical marbling. |
| Where is it found? |
PepMV has previously only been reported from the coastal region of Peru in pepino (Solanum muricatum) in the 1970s. This plant is native to the Andes and is also called melon-pear or pear-melon: it has crisp, juicy aromatic fruits which are eaten fresh.
Recently, PepMV has been found on tomato crops in the UK and in The Netherlands. While the UK and Dutch PepMV isolates (from tomato) seem to be very similar, there are some differences when compared with the Peruvian isolate from pepino. These data, together with differences in host responses (e.g. the isolate from pepino does not show symptoms in tomato), strongly suggest that the new tomato isolate may represent a distinct strain of PepMV.
| How does it develop? |
In protected tomato production, the indications are that there is a very rapid development of the disease which spreads at a much faster rate than similar viruses, such as Potato virus X (PVX), and as fast or faster than Tomato mosaic virus (ToMV). Spread is mainly along the plant rows but the disease may suddenly appear spreading rapidly from new foci in other parts of the house.
| What is being done? |
The staff at affected nurseries, are taking measures to eliminate the disease. These include destruction of affected plants and thorough hygiene precautions to prevent transmission of the virus both mechanically and during propagation.
As the original Peruvian isolate of PepMV was not seed-borne, it was thought unlikely that the UK isolate would be seed transmitted either. However, there is strong circumstantial evidence to suggest that it may be transmitted by seed at a very low rate, or possibly on contaminated debris that may come into contact with the seed. Experimental work is being done in The Netherlands and the UK on all aspects of the disease.
| What should I do? |
Regular monitoring of young tomato crops is vital so that the first signs of PepMV are detected. At this stage, elimination of the virus is most likely to be successful. Growers or consultants who suspect the presence of the disease in a crop should report it immediately to their local DEFRA Plant Health and Seeds Inspector who will visit and take samples for free confirmatory testing at the Central Science Laboratory.
|
Department for
Environment, Food and Rural Affairs 2000 PB 5186 |
CENTRAL SCIENCE LABORATORY |  |
Page last modified:
20 Nov 2006
Page published: 27 May 2004