We all have a duty to take biosecurity very seriously to prevent the establishment of new plant pests, diseases and invasive species in the UK which could have serious impact on the environment and society.

 

Xylella

Xylella is a very damaging bacterial disease which has been found in Italy, Spain, the Balearics, Southern France, Corsica and Germany. The disease is already well established in the Americas.

Xylella fastidiosa, which has many subspecies and strains, is not known to occur in the UK. It is one of the most harmful bacterial plant diseases in the world, currently known to affect 650 species. It can cause severe losses in a wide range of hosts and is spread by specific xylem-feeding insect vectors. An outbreak of this disease will trigger immediate stock destruction within 100 m and a movement ban of host plants within a 5km radius for up to 5 years. One of the most challenging aspects is that some host species remain asymptomatic despite the presence of the disease, so visual checks alone are not sufficient. Also, the symptoms vary with the host and can look identical to abiotic disorders e.g., drought.

 

We wish to continue to use measures at BBC Gardeners’ World Live events which provide a common-sense approach to eliminate any possibility of the disease being present on any plants sold or displayed at our shows. Exhibitors should familiarise themselves with information provided on the HTA website regarding Xylella, and the DEFRA website regarding the ‘risk’ host plants and the Plant Passport procedure.

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The host plants identified as highest risk are shown on the EU updates on the DEFRA website. It currently shows the following ‘high risk’ species:

 

• Polygala myrtifolia     -   Myrtle leaf milkwurt                                                                       

• Olea europaea   -   Olive

• Rosmarinus officinalis   -   Rosmery

• Lavandula sp.   -   Lavender

• Prunus amygdalus.   -   Almond

• Nerium oleander   -   Oleander

• Coffea    -   Coffee

• Hebe sp.   -    Shrubby Veronica

• Spartium junceum   -   Spanish broom

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Of these, special measures have been introduced for the importation of olives, rosemary and lavender which are considered to be of higher risk.

 

Xylella also affects a range of other important common garden plant hosts which includes:

Acer

Fraxinus

Platanus

Quercus

Ulmus

Vaccinum

Vitis

Plant passports are required to move plants within the UK and EU, and additionally special measures will be in place at BBC Gardeners’ World Live events as indicated below. It may take 18 months for symptoms to be shown on plants, and it is essential that the provenance of all plants is known, ensuring that plants are only acquired from known and reliable sources located outside any of the areas where Xylella is present. As a result we require you to adhere to the following guidelines:

• We urge all exhibitors (both nurseries and gardens) to use wherever possible British grown plants.

• All plants on the ‘high risk’ list used for our events must have been in the UK for a minimum of 18 months prior to the date of the event. Where plants originate from an area affected by Xylella, legislation requires plants to be quarantined for a minimum of 12 months before being exported. Other non ‘high risk’ plants may be used if accompanied by relevant plant passports, even if they have not been in the UK for this period. It is key that all exhibitors are aware of the provenance of all plants used at the show.

• Where plants have been imported with plant passports, exhibitors should satisfy themselves that the passports are timely and relevant to the consignment concerned.

Please visit the DEFRA and APHA Plant Health Portal for updates and more detailed information.

 

Potentially Harmful Plants

Most plants do not present any hazard to humans and incidents are rare. However, it is the responsibility of exhibitors to avoid risks and potentially harmful plants must be clearly identified with visual warnings if they are in a position accessible to visitors. It would be clearly preferable to avoid siting plants known to have skin or eye irritant qualities at the front of a stand. Exhibitors should have regard for the Code of Recommended Practise relating to the Labelling of Potentially Harmful Plants published by the Horticultural Trades Association.

 

Other Plant Health Issues

Exhibitors should familiarise themselves with restrictions which are in place regarding the sale, display or movement of the following genus:-

• Oaks Subject to an import ban due to the Oak Processionary Moth (OPM). Also Sudden Oak Death can be a problem caused by the fungus-like organism Phytophera ramorum which is a threat to Larch species (amongst others) in the UK.

• Pines Subject to Pine Processionary Moth (PPM) similar to Oaks above.

• Ash Movement of Fraxinus is restricted due to the spread of Ash dieback caused by the fungus Hymenoscyphus frazinus which blocks the water transport systems in trees causing leaf loss and dieback.

• DEFRA have identified Tobacco whitefly (Bemisia tabaci) as a major pest affecting over 800 plant species and a vector for over 110 plant viruses. Please be vigilant for this pest on imported plants. Tobacco whitefly is a notifiable pest and must be reported to APHA immediately.

• Other pests affecting plant health are Box tree moth, Phytophthora, Horse chestnut leaf miner and Ash dieback.

 

Sustainability and Environmental Measures

The organisers reserve the right to demand the removal of any plants or other materials which compromise the following policies:

• The Organisers do not permit the display or use of plants, mosses gathered from an SSSI or equivalent, bulbs or corms which have been collected from the wild.

• The Organisers require exhibitors to comply to CITES as implemented by conservation legislation designed to protect wild plants and their habitats.

• Exhibitors are required to be familiar with the prohibited and controlled plants as specified by DEFRA and APHA. Such plants include those which have narcotic qualities.

 

Non-Native Invasive Plants

 

What are non-native plants?

Non-native species are those that occur outside their natural range due to direct or indirect introduction by humans.

Many of these species do not present a problem but some that spread and outcompete native species can threaten ecosystems, habitats or native species-resulting in environmental or economical damage.

 

 

What UK legislation covers invasive and non-invasive plants?

 

The Wildlife and Countryside Act 1981 recognised the need to control certain species of invasive plants and animals already causing a problem in the UK, listing them in Schedule 9.

Originally Giant Hogweed (Heracleum mantegazzianum) and Japanese Knotweed (Fallopia japonica) were listed. In April 2010, 36 additional plants were added onto Schedule 9 and in April 2014 a ban on sale of five of the worst invasive water plants in the UK came into force.

The banned species are:-

Azolla filiculoides

Crassula helmsii

Hydrocotyle ranunuculoides

Ludwigia grandiflora and L. peplpoides

Myriophyllum aquaticum

 

Please visit the DEFRA and APHA websites for updates and more detailed information.