Pest categorisation of Tatter leaf virus

Abstract

The EFSA Panel on Plant Health performed a pest categorisation of Citrus tatter leaf virus (CTLV) for the EU territory. This virus is the causal agent of tatter leaf and graft incompatibility in trifoliate orange (Poncirus trifoliata) and its hybrids. CTLV is now recognised as a synonym of Apple stem grooving virus (ASGV), the type Capillovirus species, for which efficient diagnostics are available. There are no known ASGV vectors. The virus is reported in citrus from many countries. In the EU, while ASGV is widely present on apple and pear, it has never been reported on citrus. Since the citrus plants for planting pathway is closed by existing legislation, the main pathway for entry is plants for planting of other host species. In the EU, the high prevalence of ASGV in non-citrus hosts, but its absence in citrus ones suggests that interspecific host transfers are rare. However, there are high uncertainties on the importance and specifics of such host change events. No limits to the establishment of ASGV are identified and spread is likely through the vegetative propagation and trade of infected hosts. Infection of sensitive citrus rootstocks leads to stunted growth and decline of the entire plant a few years after grafting. The rootstocks that are now widely used to prevent citrus tristeza decline are the most affected. Among the criteria evaluated by EFSA for an organism to qualify as a Union quarantine pest, ASGV does not meet the criterion of being absent from or under official control in the EU territory. ASGV satisfies all the criteria evaluated by EFSA to qualify as a Union regulated non-quarantine pest. The main uncertainties concern the possible unreported presence of ASGV in citrus in the EU, the existence and efficiency of interspecific host transfers and the existence of ASGV natural spread.

First Detection and Molecular Characterization of Apple Stem Grooving Virus, Apple Chlorotic Leaf Spot Virus, and Apple Hammerhead Viroid in Loquat in Spain

“…ASGV (CTLV) is a citrus pathogen fulfilling all the criteria to qualify as a Europeanregulated non quarantine pest (RNQP) according to the European Food Safety Authority (EFSA) [7]. Moreover, ASGV has been reported to infect citrus in Cyprus [30].…”

“…Apple stem grooving virus, also reported as citrus tatter leaf virus (CTLV), is a member of the family Betaflexiviridae, genus Capillovirus [7]. This virus was reported for the first time in the 1960s in the USA, as CTLV, infecting "Meyer" lemmon [8] and, as ASGV, infecting apple [9][10][11].…”

“…This virus was reported for the first time in the 1960s in the USA, as CTLV, infecting "Meyer" lemmon [8] and, as ASGV, infecting apple [9][10][11]. Since then, ASGV has been reported to infect a wide range of hosts belonging to different plant families including other citrus species, pear, apricot, cherry, lily, bamboo, soybean, fava bean, and tomato and shown to be broadly distributed worldwide [7,12,13]. Recently, ASGV has also been found to infect loquat in China, another natural host of this viral species [2].…”

PM 7/31 (2) Citrus tristeza virus

“…It should also be noted that the term 'strain' has been used in literature both as a synonym for 'isolate' and to group isolates on their molecular and/or biological properties (EFSA, 2017). Therefore, in this protocol the Panel on Diagnostics in Virology and Phytoplasmology decided to use the concept of phylogenetic group in relation to genetic characteristics and strain in relation to pathogenic characteristics.…”

“…Biological indexing of these isolates resulted in rare occurrence of inconspicuous symptoms on indicator plants. Outside of Europe, in the main citrus producing countries of the world, CTV isolates causing stem pitting appear to be present (EFSA, 2017).…”