Pea viruses: Investigating the current knowledge on distribution and control of pea viruses

Summary: Globally, approximately 130 different viruses have been detected from pea crops. In the majority of cases these viruses are either not present in the UK or Europe (e.g. Cowpea mosaic virus) or, are present in other plant hosts but have not been recorded from pea crops in Northern Europe. In total around 40 viruses are known to occur in UK which have also been recorded with pea as a susceptible host. These range from viruses which are known to occur in the field (e.g. Pea seed-borne mosaic virus) to those which are unlikely to affect UK pea crops due to a lack of suitable vectors in the field (e.g. Tomato spotted wilt virus). However, there are also a significant number of these viruses which are present in the UK, and are commonly the cause of crop losses in other hosts, however there is limited knowledge regarding the status of most of these viruses on pea crops.  

 

The current distribution and impact of pea viruses in the UK is not known. However, from experience in both peas and other crops these losses will constitute both loss of yield and reduction in quality. Research in other countries has attributed yield losses due to infection with Pea seed-borne mosaic virus (PSbMV) alone between 13 to 25%. Whilst incidence of such viruses will vary from season to season as well as geographic location, based on current production values this could represent an overall loss to the industry in excess of £12 million per annum.

 

In addition to yield reduction, viruses also affect crop quality.  Infection with PSbMV can cause surface blemishing of produce and seed. Vining peas for the frozen market are rejected for use when surface blemishing is present at high levels. In cases where low levels of surface blemishing are present, losses are sustained as blemished peas are removed from processing lines, and the cost of this waste is passed on to growers. Peas become unsuitable for use as seed when PSbMV is present due to the seed-borne nature of the virus and the risk of high transmission rates from seed to plant, and further transmission by aphids within crops and to surrounding crops.

 

Alongside these established problems are emerging risks in neighbouring countries. The German pea industry has witnessed the distribution of a newly emerging, highly damaging virus (Pea necrotic yellow dwarf virus) increase from its first diagnosis in 2009 to a nationwide distribution in 2016. Viruses from the same group have also been detected in several other European countries.

 

Due to the lack recent UK focused literature quantifying such impacts or recommending management measures is difficult. Research on impact, diagnostics, and management of pea viruses has been carried out by several research groups around the world.  Although still limited, these studies may provide some answers to the current knowledge gaps with respect to pea viruses in the UK. 

 

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