Action taken to fight pathogen

'This disease highlights just how vulnerable the ornamental industry is,' says nursery consultant.

Oleander: risk posed by disease (credit: HW)
Oleander: risk posed by disease (credit: HW)

The EU has strengthened its measures to prevent the spread of the Xylella fastidiosa plant pathogen. The list of regulated plants has been expanded to 160 species and 27 genera.

Imports of all the specified plants will be subject to a declaration from the National Plant Protection Organisation of the country of origin showing imports come from X. fastidiosa-free countries, areas, sites and facilities.

Nursery consultant John Adlam said: "The bacterium has several ornamental host plants and has the potential to impact the ornamental plant market on those species if, for example, a ban on sales was invoked.

"It seems there is a suspect infection in Salento, Italy, and a previous finding in the Lecce province of Apulia that may be why there is a renewed interest in it. Growers importing material from these regions should be particularly cautious and inspect all plant material well.

"The interest in the disease comes at an interesting time for the UK grower as we do not have a good range of control products for bacterial problems. We lost the approval of the main eradicant, Cuprokylt, but through the hard work of AHDB Horticulture it has just been restored, albeit on outcrops only (EAMU 1176/2015)."

He added: "At this stage we do not have a specific approval for any product to control the disease under protection. If it did break out in any major way in the UK we do not have a good range of control products available to us so in one respect the threat is of concern. This disease highlights just how vulnerable the ornamental industry is through the dire lack of minor use control product approvals".

Imports of the species of plants susceptible will be permitted only from third countries that have clarified their pest status and provided the relevant additional declarations are included on phytosanitary certificates.

The Animal & Plant Health Agency said: "This is in response to developments in Italy, where this disease has been affecting olive trees in Lecce, and also following interceptions of X. fastidiosa on imported Coffea plants.

"There is an obligation for member states to undertake surveillance for the pathogen, including enhanced scrutiny at points of import."

Wide range of host plants at risk from pathogen

"X. fastidiosa is reported to infect more than 100 different host plants. The main commercially economic hosts are grapevine (Vitis vinifera, V. labrusca, V. riparia), citrus (Citrus spp., Fortunella), almond (Prunus dulcis), peach (P. persica), coffee (Coffea spp.) and oleander (Nerium oleander). It has also been reported on other fruit crops - Asian pear (Pyrus pyrifolia), avocado (Persea americana), blueberries (Vaccinium corymbosum, V. virgatum), Japanese plum (Prunus salicina), pecan (Carya illinoinensis), plum (Prunus domestica), sour cherry (Prunus cerasifera) - as well as on many amenity trees - American sycamore (Platanus occidentalis), American white elm (Ulmus americana), liquidambar (Liquidambar styraciflua), oaks (Quercus spp.), red maple (Acer rubrum), red mulberry (Morus rubra).

X. fastidiosa - and detected in lucerne (Medicago sativa). Numerous wild plants and weeds can carry the bacterium without symptoms (wild grasses, sedges, lilies, bushes and trees). Surprisingly, olive (Olea europaea) has rarely been mentioned as a host plant. However, studies were recently initiated in southern California because increasing olive tree mortality was reported from the Los Angeles area.

X. fastidiosa was consistently detected in olive trees showing branch dieback and leaf scorching but its pathogenicity could not be fully demonstrated."

European Plant Protection Organisation _fastidiosa.htm

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