The HTA statement reads: "We have taken the decision not to knowingly purchase any host plants originating from regions where the disease Xylella is known to exist. The decision has been taken after detailed consideration as to the potential catastrophic impact the introduction of the disease could have to the UK environment, coupled with the ever increasing number of host plant genera of this disease. This is in line with Defra’s good-practice recommendations."
HTA statement issued on behalf of:
- Bransford Webbs Plant Company
- Golden Grove Nursery
- James Coles and Sons (Nurseries)
- Johnsons of Whixley
- Lovania Nurseries
- Oakover Nurseries
Areas involved include Corsica, parts of Provence, Liguria, Monaco, Saxony, Thuringia, the Balearics, Alicante and Apulia. There are more than 300 hosts including cistus, olives, lavender and polygala.
"Responsible nurseries will be going further. They will be assessing the risk that Xylella presents to their business by considering their business practices and they will be making changes to the way they do business to mitigate that risk. That is certainly what Boningale is doing and I know others are following the same line.
"We haven’t signed up to this statement, not because we are not performing to this standard but because we perform to a far greater standard and we worry that by signing to this statement we will suggest to others that this minimum is adequate. It is not."
Retail awareness of Xylella is "growing rapidly", he says. A new HTA commercial committee chaired by Scotsdales' Caroline Owen and bringing together retailers and suppliers from some defunct committees held its first meeting this month and discussed the issue.
But Curtis-Machin admits: "It's taken time to get through to other sectors where there are different business imperatives. If a grower gets the disease, that's it. But for a retailer and landscaper it should be something to worry about too. Retailers are looking carefully at the supply chain, but nothing's happened yet."
He says: "There's such a potentially big impact it almost can't be true," adding that it could be better to err on the side of including whole genera when looking at which plants are hosts.
Nursery consultant John Adlam says he and the HTA "looked at the overall importance of biosecurity in a nursery and encourage growers to look at where their plants are being sourced from and to know the integrity of that provenance." The lack of any products to control Xylella is a concern, he adds.
Oakover Nurseries general manager Brian Fraser, who is chair of the HTA tree and hedging group, says: "All members of the HTA tree and hedging group place the utmost of importance on plant health. Many members are or were already applying various further stringent import measures, with some not importing any plants at all.
Adlam says: "It is serious and the seriousness of it needs to be grasped. If a nursery had an outbreak and that 10km radius comes into play, my fear is there could be litigation for loss if trading. This brings even more of a pressure on people to be very careful about where they buy from. So it's not just the biosecurity element, it's the litigation element as well."
He adds that there is concern about landscapers and building developers who buy plants direct and retailers who buy from traders.
Animal & Plant Health Agency principal inspector Ed Birchall, speaking at Hort Science Live at Bransford Webbs, said there are three Xylella subspecies — pauca, multiplex and fastidiosa. He added that the meadow spittle bug vector is present in the UK "so we have to try and keep the disease out".
Birchall showed pictures from Italy of browning symptoms and necrosis. There are different symptoms on different hosts. There is a five-year 10km demarcation zone and 100m area where hosts have to be destroyed. He said interception is preferable to an outbreak because there is no need for demarcation.
The heel of Italy has given up trying to control Xylella on hosts such as olives and vinca. In France, on acer, prunus and other hosts the area hit is in the south east and Corsica, including in the wild. Germany has Nerium oleander and Erysimum hosts in Saxony and Thuringia. The Balearics have all three subspecies on plants such as Olea and prunus. The Alicante area has an outbreak on almond trees.
"Growers and retailers need to have serious thoughts about where they buy material and origin of mother stock," said Birchall, while having your own mitigation "might be very challenging to trace back". He advised using Defra's plant health portal.
Birchall said it "makes life simple" if genera are looked at rather than species. He suggested visiting suppliers or getting YouTube videos of nurseries sent, as well as using quarantine, record keeping, good nursery hygiene, destroying old plants, stock separation, training and feedback from staff.
Ayletts Nurseries horticultural manager Marcus Cousins says: "We work very carefully with suppliers and visit them. There are regions we won't buy from. It's all about traceability. We shouldn't be complacent. Some retailers are complacent. It's not naivety, it's lack of knowledge."
He adds that Ayletts added Xylella policy to its company manual in February 2016 after an HTA conference at the Food & Environment Research Agency in York.