This rapid assessment shows:

Likelihood of entry: Entry of the pathogen has already occurred. Potential for future entry is considered to be likely on imports of seed and plants for planting of sweet basil (O. basilicum), Agastache and coleus (S. scutellariodes) and possibly other members of the Lamiaceae from countries where the pathogen occurs. Potential for future entry is moderately likely on plants and cut leaves of sweet basil (O. basilicum) and possibly other herbs that are members of the Lamiaceae from the same countries. 

Likelihood of establishment: The pathogen may already be established in the UK. However, only an official survey would determine whether this was the case. Based on the existing (and seemingly growing) international distribution of this pathogen, it is very likely that P. belbahrii could establish on sweet basil (O. basilicum), and/or Agastache grown in the UK both outdoors or under protection. Coleus is grown as a house plant and so is produced under protection. The pathogen could also establish on this host. Other members of the Lamiaceae may also support establishment of the pathogen but their susceptibility is not known. 

Economic impact: The potential economic impact of P. belbahrii in the UK is rated as medium. It is possible that without controls the pathogen could cause total crop losses in sweet basil (O. basilicum). The value of the fresh basil herb industry in the UK has been estimated to be in the order of 10’s of millions of UK sterling. Other plants are at risk including the ornamental hosts Agastache and the house plant coleus (S. scutellariodes) and possibly other members of the Lamiaceae. 

Endangered area: All areas of the UK where sweet basil, Agastache, coleus (S. scutellariodes) and potentially other members of the Lamiaceae family are grown both outdoors and under protection. 

Risk management: This pathogen has the potential to be managed by non-statutory means outlined above in response to question 15. In the first instance this involves sourcing clean planting material (seeds and plants), and good crop management including managing humidity and leaf wetness. Where outbreaks have occurred removal and safe disposal of infected plants/plant debris followed by hygiene measures on the place of production to prevent spread in neighbouring or subsequent crops will be necessary. Chemical (fungicide) treatments of seed with an approved product may be beneficial. Treatment of plants in new or adjacent crops (protectant sprays) should only be undertaken with approved products and in conjunction with cultural control. Ensuring the use of fungicides with different modes of action will help prevent the development of resistance to phenylamides (often used against downy mildews) in this species.