DEFRA TECHNICAL NOTE DATED 29th APRIL 2008

PROHIBITED IMPORT OF LYCIUM BARBARUM PLANTS - UPDATED TECHNICAL NOTE

Goji berry plants (Lycium barbarum) are a solanaceous plant and their import (not the berries, just the plants) into the UK from most countries outside Europe is prohibited. Only plants originating from outside the Euro-Mediterranean area (i.e. countries other than Europe, Algeria, Egypt, Israel, Jordan, Lebanon, Libya, Morocco, Syria, Tunisia or the area of Turkey east of the Bosphorus Strait known as Anatolia) are of concern. This is due to the risk of these plants carrying diseases which could infect closely related plants, in particular potatoes and tomatoes.

At least 86,000 plants are known to have been distributed. Those which have gone to nurseries and garden centres have been withdrawn from sale and are currently awaiting destruction or re-export.. However, many of these plants have been sold by mail order between May and October 2007 and during April 2008.

There is little available information on the pest and diseases of goji berry plants. However, as these are a solanaceous plants they have the potential to be infected with a number of diseases which, if present, could pose a significant risk to UK tomato and potato production. Of particular concern would be the potential for these plants to carry viruses and viroids.

At this stage, testing of samples of imported goji plants has shown no detection of quarantine(organisms not established in the EU but of plant health concern) in the limited number of plants analysed by Defra’s Central Science Laboratory (CSL) but further testing is underway. A common non-quarantine virus, cucumber mosaic virus, has been found in some of the samples and this virus affects a number of hosts including ornamentals as well as cucumbers, tomatoes and peppers. Control and hygiene advice is provided on the RHS website at: www.rhs.org.uk/advice/profiles0603/tomato_virus.asp

The common disease potato blight (Phytophthora infestans) infects some plants in the Solanaceae family such as potato, tomato and peppers. Goji berries are also in this family but there is no evidence in the scientific literature, or and elsewhere, of blight occurring on this species. However blight is known to infect other species of Lycium, so there is a strong possibility goji berry plants may also be susceptible under suitable climatic conditions. Therefore it is suggested growers monitor these hosts for signs of blight and remedial action taken if possible. The effectiveness of any fungicides that may be used on goji berries against blight is not known, however, nor their plant host reaction. Blight normally only infects leaves and as goji plants are normally traded and sold without foliage it is very unlikely the imported goji plants themselves will be a source of introducing new infection.

As information on diseases of goji berry is very limited, even after testing it cannot be guaranteed that all plants are free of harmful pests and diseases, in particular low levels of harmful viruses and viroids. The main concern is that if such organisms, particularly insect-transmitted viruses are present, they could be spread to commercial solanaceous crops, such as potato or tomato. Also as goji plants are perennials and relatively winter hardy plants they have the potential to be source of infection for many years. The other issue is that potentially transmission could occur to naturalised plants nearby which could also act as a source of infection for subsequent years.

An initial assessment by CSL suggests that such a risk is relatively low, as there are generally limited connections between amateur and professional production. Also commercial growers of potatoes and tomatoes tend to be well aware of potential risks associated with other solanaceous plants. However, in particular, tomato growers (and growers of other solanaceous glasshouse crops) should consider carefully what other plants are grown on their nursery and if this includes solanaceous plants appropriate hygiene measures should be implemented. Potato growers (especially seed potato growers) should be aware there is a theoretical risk to potatoes from exposure to other solanaceous material, but this is extremely unlikely under normal (i.e. in the field) growing conditions. Transmission of harmful organisms, such as viruses and viroids from the goji plants, if present, could take place to gardeners’ potato crops by mechanical or insect transmission, which could act as a reservoir if potatoes are kept as seed for the following season. However, it is always recommended that amateur potato growers buy in new seed potatoes every year as planting of home saved seed or ware (eating potatoes) increases the risk of disease in the plants and subsequently a poor crop. There would also be a risk of transmission to amateur growers’ tomatoes (or peppers and aubergines) but, as these are annual crops, the risk of continuing infection is limited. If you have bought some of these plants, to avoid any risk to your other garden crops, it is recommended that you remove them, seal them in plastic bags and dispose of them in household waste for landfill. They should not be placed in green waste bins or garden compost. In addition after handling these plants wash your hands thoroughly before touch other solanaceous plants and clean any tools used on them thoroughly with hot soapy water.

For more information contact your local Plant Health and Seeds Inspector.

DEFRA TECHNICAL NOTE DATED 29th APRIL 2008

Thompson & Morgan Stockists

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