The approach of summer is usually the start of prime time for the nation’s salad vegetable growers, but Australian carrots and celery have been declared under threat from an exotic bacterium rampaging across Europe.

Know as Candidatus Liberibacter solanacearum, the bug causes leaf curling, leaf yellowing, stunting and root abnormalities in carrots and celery and it has already spread rapidly across countries including France, Norway, Spain, Sweden and Morocco.

Australia has so far remained unaffected, but the Department of Agriculture is now sufficiently worried that it has triggered a new biosecurity alert and introduced much tougher testing and screening after determining that carrot seed and carrot and celery tissue cultures now represent a high level of quarantine risk.

Carrot seeds will now undergo heat treatment or molecular testing as well as screening in post-entry quarantine facilities and there will be molecular testing for carrot and celery tissue cultures.

Tissue cultures will also be screened for a minimum of 3 months in a government quarantine facility before being tested to ensure they are free of the bacterium.

The new measures came in last month to protect the carrot and celery industries, which are worth $190 million and $34 million a year respectively. Most carrots in Australia are grown from seed.

International stakeholders have been notified of the emergency measures through the World Trade Organization Sanitary and Phytosanitary notification system, with a 60 day implementation period.