Where are they now?
The EPPO A Lists of quarantine organisms are continually being examined and, if necessary, revised by the technical bodies of the Organization, to take into account changes in distribution of the organisms, appearance of new races or strains, differences in agricultural practices and other recent scientific information. As a result, some organisms have been removed from the lists. The reasons for their removal and, indeed, their very disappearance have not always been noted by member countries. The following notes briefly explain why certain organisms are no longer recommended for inclusion in national lists.
No Pest Removed from lists in
25 Blackberry dwarf 1981
56 Pseudomonas syringae pv. glycinea 1984
59 Xanthomonas campestris pv. hyacinthi 1984
65 Cochliobolus heterostrophus 1981
72 Hypoxylon mammatum 1984
86 Apple chat fruit MLO 1984
89 Beet curly top virus 1984
99 Rose wilt 1984
107 Diarthronomyia chrysanthemi 1984
109 Eriosoma lanigerum 1984
123 Ditylenchus destructor 1984
132 Agrobacterium rhizogenes 1984
156 Phytophthora infestans mating type A2 1987
25 Blackberry dwarf, noted 50 years ago as a disease of trailing blackberries * and loganberries * in the western United States, is not as important as it once was. In fact, it is now difficult to find plants exhibiting dwarf symptoms. It is thought that the disease resulted from the presence of a combination of two or more Rubus viruses (tobacco streak virus, black raspberry necrosis virus, tomato ringspot virus, raspberry bushy dwarf virus) in poor-quality planting material. It was deleted from the A1 list in 1984.
56 Pseudomonas syringae pv. glycinea has now been reported from all the soybean-growing countries of Europe and appears to be present wherever soybeans are grown.
59 Xanthomonas campestris pv. hyacinthi, like the above bacterium, seems to be universally associated with its host, in this case hyacinth. It clearly falls into the category of a 'quality' organism rather than a quarantine pest. Both this bacterium and the one above were deleted from the list in 1984.
65 Cochliobolus heterostrophus, the causal agent of southern leaf blight of maize, was put on the A2 list because of the devastation in the 1970's to certain maize cultlvars in the USA. It was removed from the list when it was realized that susceptible cultivars were no longer grown in Europe.
72 Hypoxylon mammatum, a canker of Populus spp., was originally thought to be introduced from America but is now believed to be indigenous to Europe and quite widely distributed in mountain areas. European cultivars are practically all resistant, so anxiety raised by the seriousness of the disease in North America was felt to be unfounded in relation to the EPPO region and the organism was deleted from the A2 list in 1984.
86 Apple chat fruit MLO is a pathogen of only a few cultivars of apple in which, during climatically suitable seasons, yield can be reduced by 30 % and fruit size by about 25 %. The causal organism cannot be detected by serological methods, only
by indexing. on a sensitive host. It was decided, however, that it did not qualify as a quarantine organism because it had been widely distributed throughout Europe for, many. years in latently infected certified planting material without causing any noticeable problems. In addition to the fact that the known susceptible cultivars are now not commonly grown as orchard trees, it is probable that the climatic conditions in the major apple-growing areas seldom correspond to those required for symptom expression. It was deleted in 1984.
89 Beet curly top virus was deleted from the A2 list in 1984 on the grounds that the virus had reached its natural limit of spread in Europe and that it had so many host plants that no meaningful requirements could be formulated.
99 Rose wilt was discussed by the Panel on Phytosanitary Regulations in 1983 and it was agreed that the existing evidence could not prove that this was anything more than a symptom, with differences observed in different parts of the world. The cause was unknown and may, in fact, be ascribed to one or many biotic and/or abiotic factors. A survey of the literature since its deletion in 1984 reveals little reference to the disease and no indication of a causal agent.
* Rubus fruticosus and R. ursinus.
107 Diarthronomyia chrysanthemi, in addition to being widespread within the region, was considered to be easy to control, and was therefore deleted from the A2 list in 1984.
109 Eriosoma lanigerum, the woolly apple aphid, is now known to be very widely distributed throughout the EPPO region. It is absent only from Norway, which was not considered sufficient justification for making it a quarantine pest for the whole region.
123 Ditylenchus destructor, the potato tuber nematode, is also known to be very widely distributed throughout the EPPO region.
132 Agrobacterium rhizogenes, although only reported from a few EPPO countries, is little known in Europe and its real distribution could be much wider. The damage caused is not reported to be very great and it was, therefore, not considered worthy of A list status.
156 Phytophthora infestans mating type A2 was originally added to the A1 list because it was feared that the presence of this perfect stage mating type (at that time thought to be confined to Mexico and adjoining countries) would provide the fungus with possibilities for genetic recombination to overcome host genes for resistance. However, it has now been detected in several European countries and the fact that it can spread with great ease and is very difficult to distinguish from the A1 mating type convinced the Working Party on Phytosanitary Regulations that not only was it not an A1 pest but there was no point in transferring it to the A2 list. It was deleted from the lists in 1987.
Finally, it may be noted that some A1 entries of the original list have disappeared into broader categories:
11 Endocronartium harknessi now included with 9. Cronartium spp. (non-European)
18 Peridermium kurilense " 9. Cronartium spp. (non-European)
61 Xanthomonas phaseoli var. " 60 Xanthomonas campestris pv. phaseoli
fuscans
29 Potato yellow dwarf " 128 Potato viruses (non-European)
30 Potato yellow vein virus " 128 Potato viruses (non-European)
39 Hylurgopinus rufipes " 43 Scolytidae (non-European)
These organisms were not considered sufficiently important in themselves to be individually listed.
Sources
EPPO Secretariat (1988-04).