Two rows of approximately 100 plants in total in a glasshouse of 5,000 tomato plants grown for commercial fruit production. It is possible 22,000 plants in other glasshouses on the same site are grown from the same stock and this is being investigated. The origin of the seed of both the variety and rootstock variety and the location other crops grown from the same seed stocks are being followed up to help determine the origin of the infection and if any further crops are infected.