New data on quarantine pests and pests of the EPPO Alert List
By searching through the literature, the EPPO Secretariat has extracted the following new data concerning quarantine pests and pests included on the EPPO Alert List. The situation of the pest concerned is indicated in bold, using the terms of ISPM no. 8.
- New records
The presence of Citrus tristeza virus (Closterovirus, CTV – EPPO A2 List) is reported for the first time in Afghanistan. CTV was detected in the citrus orchard of the National Collection Experimental Farm in Jalalabad (Nangarhar province). Four accessions were found infected by CTV (Citrus japonica cv. ‘Margarita’, C. sinensis cv. ‘Mahali’, C. reticulata cv. ‘Fruter’, C. jambhiri cv. ‘Mahali’) (Rehman et al., 2012). Present, few records.
A phytoplasma associated with symptoms of witches’ broom on Ulmus parvifolia has been detected in symptomatic samples collected from Taiwan and Shandong province in China. Molecular analysis revealed that this phytoplasma was closely related to ‘Candidatus Phytoplasma asteris’ (Gao et al., 2011).
- Detailed records
In mid-July 2010, symptoms of Iris yellow spot virus (Tospovirus, IYSV – formerly EPPO Alert List) were observed for the first time in Pennsylvania (US). The disease was found in onion plants (Allium cepa cv. ‘Candy’) in a small farm in New Holland, Lancaster county. Laboratory analysis confirmed the identity of the virus (Hoepting and Fuchs, 2012).
Since the 1970s, Tilletia controversa (formerly EPPO A2 List) has almost disappeared from Hungarian wheat crops but surveys are regularly being carried out to verify that wheat shipments are free from it. From 2007 to 2010, numerous wheat samples were analysed and found free from the fungus. But in 2011, 1 sample originating from Pölöske (Zala county) was found infected by teliospores of T. controversa. Investigations are planned to delimit the extent of the infestation and to understand why it reappeared in Hungary (Halász, 2012).
In November 2011, the presence of Tomato yellow leaf curl virus (Begomovirus, TYLCV - EPPO A2 List) was detected in bean fields (Phaseolus vulgaris) in Huaibei, Northern Anhui Province, China (Ji et al., 2012).
- New host plants
Natural infections of Citrus leprosis virus C (CiLV-C - EPPO A1 List) have been detected in Commelina benghalensis (Commelinaeae) which is a common weed in citrus orchards in Brazil. However, the possible role of this weed in the disease epidemiology remains to be studied (Nunes et al., 2012a). In addition, transmission experiments with the mite vector, Brevipalpus phoenicis, have showed that the following species were also susceptible to CiLV: Hibiscus rosa-sinensis, Malvaviscus arboreus, Grevilea robusta, and Bixa orellana. These plants are commonly planted as hedgerows and windbreaks in Brazilian citrus orchards (Nunes et al., 2012b).
Inoculation studies have showed that 3 North American native plants, Rhododendron macrophyllum, Rhododendron occidentale and Umbellularia californica, were susceptible to Phytophthora kernoviae (EPPO Alert List). It is noted that these plants might be at risk if the pathogen was introduced into North America, and that they could also serve as pathways for the disease introduction (Fichtner et al., 2012).
Inoculation studies have showed that 66 Australian native plants were susceptible to Phytophthora ramorum (EPPO Alert List). Among these plants, Isopogon formosus, Eucalyptus denticulata and Eucalyptus regans were identified as potentially highly susceptible hosts. Hardenbergia violaceae, Eucalyptus cneorifolia, Nothofagus cunninghamii, Eucalyptus viminalis and Eucalyptus sideroxylon were found to be potentially moderately susceptible hosts (Ireland et al., 2012).
Inoculation experiments have been conducted in the USA to study the susceptibility to Phytophthora ramorum (EPPO Alert List) of several weed species that can be found in containers of nursery plants. Results showed that Pteris cretica (Pteridaceae), Chamerion angustifolium and Epilobium ciliatum (both Onagraceae) showed brown lesions on the foliage and some degree of root infection. Of these species, only Epilobium ciliatum is considered to be a common weed of container nurseries. However, these results suggest that weeds should be considered when nurseries are inspected for symptoms of P. ramorum (Shishkoff, 2012).
In June 2009, unusual symptoms were observed on pea crops (Pisum sativum cv. ‘Rajnai törpe’) in North-East Hungary. Affected plants showed stem vascular necrosis, interveinal necrosis of upper leaves, wilting of flowers and necrotic spots on the pods. Laboratory studies revealed the presence of Tomato spotted wilt virus (Tospovirus, TSWV – EPPO A2 List) (Salamon et al., 2012).
- New species/new pests
Since 2007, a new disease of onion (Allium cepa) called yellow bud has been causing damage in Georgia (US). Emerging leaves display intense chlorosis and older leaves exhibit extensive leaf blight. Yield reductions can be severe due to stand loss and reduced bulb size. The causal agent was identified as Pseudomonas syringae but the pathovar could not be determined. It is noted that the disease has spread across the ‘Vidalia onion growing region’ of Georgia since it was first observed (Gitaitis et al., 2012).
Two new parasitoid species of Agrilus planipennis (Coleoptera: Buprestidae – EPPO A1 List) have been described:
- Spathius galinae (Hymenoptera: Braconidae). It was originally misidentified a S. depressithorax. This species is a gregarious ectoparasitoid of A. planipennis larvae. Specimens have been collected from the Russian Far East and the Republic of Korea (Belokobylskij et al., 2012).
- Sclerodermus pupariae (Hymenoptera: Bethylidae). This gregarious ectoparasitoid of A. planipennis larvae and pupae has been described from China (type material was collected in a gallery of A. planipennis on Fraxinus velutina, in Tianjin municipality) (Yang et al., 2012).
Sphaeropsis pyriputrescens is a new fungal species which was described in 2004 as the causal agent of a post-harvest disease of apples and pears in Washington State, USA. The fungus was originally described on pears (Pyrus communis cv. ‘Anjou’), but it was later found that Sphaeropsis rot caused more damage on stored apples (e.g. Malus domestica cvs ‘Red Delicious’, ‘Golden Delicious’, ‘Fuji’, and ‘Granny Smith’). The main symptoms of Sphaeropsis rot are stem-end rot and calyx-end rot originating from infections at the stem and calyx of fruit, respectively. Decayed tissues are firm or spongy, and turn brown. As the disease advances, the fungus may form black pycnidia in the decayed areas. S. pyriputrescens can also cause twig dieback and cankers on apple and crabapple (Malus sylvestris) trees. Infection of fruit occurs in the orchard but symptoms develop after a period of time during storage. In addition to Washington State, S. pyriputrescens was detected in British Colombia (Canada) on stored pears in 2009 (Sholberg et al., 2009).
Sources
Belokobylskij S, Yurchenko GL, Strazanac J, Zaldivar-Riveron A, Mastro V (2012) A new emerald ash borer (Coleoptera: Buprestidae) parasitoid species of Spathius Nees (Hymenoptera; Braconidae: Doryctinae) from the Russian Far East and South Korea. Annals of the Entomological Society of America 105(2), 165-178.
Fichtner EJ, Rizzo DM, Kirk SA, Webber JF (2012) Infectivity and sporulation potential of Phytophthora kernoviae to select North American native plants. Plant Pathology 61(2), 224-233.
Gao R, Wang J, Shao YH, Li XD, Yang BH, Chang WC, Zhao WJ, Zhu SF (2011) Molecular identification of a phytoplasma associated with Elm witches’-broom in China. Forest Pathology 41(5), 355-360.
Gitaitis R, Mullis S, Lewis K, Langston D, Watson AK, Sanders H, Torrance R, Jones, JB, Nischwitz C (2012) First report of a new disease of onion in Georgia caused by a nonfluorescent Pseudomonas species. Plant Disease 96(2), p 285-286.
Halász A (2012) [Survey of Tilletia species in Hungary – recurrence of Tilletia controversa]. Növényvédelem 48(5), 193-202 (in Hungarian).
Hoepting CA, Fuchs MF (2012) First report of Iris yellow spot virus infecting onion in Pennsylvania. Plant Disease 96(8), p 1229.
Ireland KB, Hüberli D, Dell B, Smith IW, Rizzo DM, Hardy GESTJ (2012) Potential susceptibility of Australian native plant species to branch dieback and bole canker diseases caused by Phytophthora ramorum. Plant Pathology 61(2), 234-246.
Ji YH, Cai ZD, Zhou XW, Liu YM, Xiong RY, Zhao TM, Yu WG, Tao XR, Zhou YJ (2012) First report of Tomato yellow leaf curl virus infecting common bean in China. Plant Disease 96(8), 1229-1230.
Nunes AM, Bergamini MP, Coerini LF, Bastianel M, Novelli VM, Kitajima EW (2012a) Citrus leprosis virus C naturally infecting Commelina benghalensis, a prevalent monocot weed of citrus orchard in Brazil. Plant Disease 96(5), p 770.
Nunes AM, de Oliveira CAL, de Oliveira ML, Kitajima EW, Hilf ME, Gottwald TR, Freitas-Astúa J (2012b) Transmission of Citrus leprosis virus C by Brevipalpus phoenicis (Geijskes) to alternative host plants found in citrus orchards. Plant Disease 96(7), 968-972.
Rehman S, Ahmad J, Lanzoni C, Rubies Autonell C, Ratti C (2012) First report of Citrus tristeza virus in National Germplasm of Citrus in Afghanistan. Plant Disease 96(2), p 296.
Salamon P, Nemes K, Salánki K, Palkovics L (2012) First report of natural infection of pea (Pisum sativum) by Tomato spotted wilt virus in Hungary. Plant Disease 96(2), p 295.
Shishkoff N (2012) Susceptibility of some common container weeds to Phytophthora ramorum. Plant Disease 96(7), 1026-1032.
Sholberg PL, Stokes SC, O'Gorman DT (2009) First report of a new postharvest disease of pear fruit caused by Sphaeropsis pyriputrescens in Canada. Plant Disease 93(8), p 843.
Xiao CL, Kim YK, Boal RJ (2011) Control of Sphaeropsis rot in stored apple fruit caused by Sphaeropsis pyriputrescens with postharvest fungicides. Plant Disease 95(9), 1075-1079.
Xiao CL, Rogers JD (2004) A postharvest fruit rot in d’Anjou pears caused by Sphaeropsis pyriputrescens sp. nov. Plant Disease 88(2), 114-118.
Yang ZQ, Wang XY, Yao YX, Gould JR, Cao LM (2012) A new species of Sclerodermus (Hymenoptera: Bethylidae) parasitizing Agrilus planipennis (Coleoptera: Buprestidae) from China, with a key to Chinese species in the genus. Annals of the Entomological Society of America 105(5), 619-627.