To ensure adequate protection against PepMV, mild isolates of both strains are required
To ensure adequate protection against PepMV, mild isolates of both strains are required
In practice, there are several different strains of the pepino mosaic virus (PepMV) that can cause problems for growers. The EPPO (European and Mediterranean Plant Protection Organization) Datasheet on PepMV says the following about this: “No resistance genes to PepMV are available in commercial tomato cultivars. Some accessions [...] are resistant to isolates of the EU strain. Whether this resistance holds against the other PepMV strains remains to be investigated.
Cross-protection
One method currently applied in various countries to control the negative effects of PepMV infections is cross-protection. Protection against severe EU strain isolates requires an attenuated EU isolate, while an attenuated CH2 isolate is required to protect against aggressive CH2 isolates. In many instances isolates of the CH2 and EU strains occur in mixed infections, so for adequate protection mild isolates of both strains are required.”
Because the two aggressive strains (CH2/EU) often occur together in a mixed infection, the use of mild isolates that protect against aggressive isolates of both strains is recommended. This provides broader protection against damage by PepMV than when a single mild isolate is used. This is endorsed by EPPO, among others.