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Effects of inoculum concentration, wetness duration and plant age on the development of tomato early blight were evaluated in relation to host susceptibility under controlled environmental conditions. The main effect of early blight was premature defoliation, which was linearly related to the percentage of leaf area showing symptoms. As ln(inoculum concentration, conidia mL 21 ) increased from 6´2 to 11´5, the percentages of leaf area affected and of defoliation increased linearly. Four h of leaf wetness after inoculation were sufficient to initiate the disease on plants of hybrid Skala RZ but not on those of cv. Rio Rojo, for which at least 6 h leaf wetness were needed. As wetness duration increased up to 24 h, there was an increase in the percentage leaf area showing symptoms and in the percentage of defoliation, but thereafter there was no significant increase in either parameter. Tomato plants were susceptible to Alternaria solani at all growth stages, but susceptibility increased as plants matured. There were no significant differences in susceptibility between tomato cultivars and hybrids.

The Panel on Plant Health conducted a pest risk assessment for Bemisia tabaci and the viruses it transmits, including an evaluation of risk reduction options and an assessment of the effectiveness of the special requirements linked to B. tabaci and the viruses listed in Council Directive 2000/29/EC. B. tabaci and a large number of viruses transmitted by this polyphagous insect occur in subtropical and tropical climates around the world. Five entry pathways for B. tabaci and associated viruses were identified, with the plants for planting pathway being most significant and rated for entry of insects and viruses as likely and moderately likely, respectively. The most invasive B. tabaci species and several of its associated viruses responsible for severe diseases in major European food crops are established outdoors in coastal Mediterranean regions. Because of similar climate requirements and host plant preferences, B. tabaci and associated viruses currently not present in Europe are likely to establish within the temperature limits set for B. tabaci. Trade between European Member States allows B. tabaci to reach greenhouses in northern Europe, including those in areas with protected zone status. Because of the cool climate, establishment and spread outdoors of B. tabaci is rated unlikely for northern Europe. This situation is likely to continue even under a climatic scenario with an increase in temperature of +2 °C. B. tabaci -transmitted viruses cause severe diseases with major negative impact on crop production when risk reduction measures are not used. Risk reduction options will also apply to B. tabaci and viruses new to Europe. Risk reductions options are evaluated in terms of reducing B. tabaci populations, crop infestations, virus incidence and the impact of diseases. © European Food Safety Authority, 2013 KEY WORDSBemisia tabaci, European and non-European Bemisia tabaci, begomoviruses, non-circulatively transmitted viruses, pest risk assessment, risk reduction options. With regard to the assessment of the risks to plant health:B. tabaci is considered to be one of the most serious threats to crop cultivation worldwide, predominantly because of the large number of viruses it transmits. In regions where B. tabaci is established, viruses transmitted by this insect, especially those affecting tomato and cucurbits, and also beans, pepper and aubergines, are responsible for severe diseases that have a strong negative impact on crop yield. As a consequence, crop production in those areas is not possible without a system-wide and comprehensive set of pest and disease management measures in place. In the risk assessment area, B. tabaci is present outdoors in coastal areas with a Mediterranean climate, and in many EU countries the pest is present in greenhouses.B. tabaci is a complex of at least 28 indistinguishable morphocryptic species, of which four occur in Europe. Two species, Mediterranean (Med, formerly referred to as biotype Q) and Middle East-Asia Minor 1 (MEAM1, formerly referred to as biotype B), a...

Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a risk assessment for Ceratocystis platani in the EU with the aim to assess the effectiveness of risk reduction options (RROs) on the basis of the mechanisms of spread identified in the pest categorisation (natural and human-assisted means, including waterways, root anastomosis, contaminated pruning tools, machinery, insects, contaminated insect frass and sawdust). C. platani is a destructive pathogen of Platanus trees, which is currently present in the EU (in France, Greece and Italy). Three scenarios were considered: the current situation (A 0 scenario); the situation without RROs (A 1 ); and the application of additional RROs (A 2 ). The risk of new introductions into the EU of C. platani by means of the main pathways of entry (i.e. plants for planting, wood and machinery, e.g. construction machinery and pruning/cutting tools) is relatively limited, but about 250 times higher for the A 1 scenario compared to the A 2 scenario (median numbers of established populations). The risk of spread from already affected EU regions is higher, but varies depending on the scenario. Machinery is the most important mechanism of long-distance spread. Focusing the additional RROs in A 2 scenario on this mechanism of spreadwhich is not currently regulated -would be an effective way to reduce the likelihood of further spread and thus impacts of C. platani to not yet affected EU regions. The emergency measures applied by the C. platani-affected EU Member States (France, Greece and Italy) could be harmonised and improved. An enhanced programme could be developed which includes surveillance, early detection of the disease foci, effective eradication measures and planting resistant Platanus clones in new plantations in affected areas. Surveillance could also be intensified in the EU MSs not yet known to be affected by the disease.

In late 2009, a European Food Safety Authority (EFSA)‐funded project (Prima phacie) began work to review and test methodologies for conducting pest risk assessment by means of case studies on three phytoplasmas (Candidatus Phytoplasma mali, Ca. P. prunorum, Ca. P. pyri); two bacteria (Acidovorax avenae subsp. citrulli, Xanthomonas citri [=X. axonopodis] pv. citri); two fungi (Guignardia citricarpa, Mycosphaerella dearnessii); two nematodes (Meloidogyne chitwoodi, M. fallax); and an insect (Anoplophora glabripennis). Multiple risk assessment schemes and methods will be applied to each of the case study pests, allowing for a comparative assessment of methods. Methods to assess the effectiveness of possible risk management options for each pest will also be evaluated. The project will further develop the scientific basis for pest risk assessment within the European Community and identify methodologies most suitable for conducting risk assessments and for evaluating the effectiveness of possible risk management options by the EFSA Panel on Plant Health in order to support European decision making. The project lasts 29 months, and is being conducted by an international consortium of 11 partners consisting of phytosanitary organizations, research institutes and a university. Results will be disseminated via conventional publications and at a workshop in March 2012.