EditorialHorizon scanning is one of the most challenging tasks facing National and Regional Plant Protection Organizations and their stakeholders; spotting the pests that might be coming and deciding what measures should be taken against them. The organisms we were worrying about twenty years ago are not necessarily the ones which have since proved most damaging. In part this is a success story because establishment of some of those pests was predicted, regulated and prevented. We need to notice, publicize and quantify those successes if we are to justify the effort needed to achieve them. Other pests, though, have arrived, spread and caused damage before there was opportunity to take effective measures; sometimes before they were known to be pests or even fully described.This issue of the EPPO Bulletin, as well as recording the spread of many different pests in different parts of the region, reports on two studies aimed at improving our ability to predict and prevent. The EPPO tomato study and the EU DROPSA project (Steffen et al., 2015) reflect lessons learned from two damaging new arrivals: Tuta absoluta and Drosophila suzukii respectively. Tuta absoluta was spotted on the horizon, but not regulated because the pathway (trade in tomato fruit from South America) was not expected. Drosophila suzukii was not seen coming because it spread so fast around the world and was in a group of insects not previously known as primary pests. The two studies are applying rapid screening to identify possible quarantine pests from among the many organisms which might be carried on consignments of tomatoes and of fruit.Improved horizon scanning will produce longer lists of potential candidates for Pest Risk Analysis. We then need the right forms of Pest Risk Analysis to identify appropriate risk management measures, to do so in good time with the resources available, and to justify the recommended measures against any likely challenges. EPPO, as our new Strategy puts it, "will use types of PRA appropriate to the needs and to the level of challenge which may be expected in view of the measures recommended, with a preference for rapid PRAs where possible." Longer lists also increase the need for prioritization; for ensuring that effort put into research, regulation, surveillance and contingency planning is targeted at those pests for which it can be most effective. Several of our member countries are working on techniques for prioritization, such as the Plant Health Risk Register described in the Bulletin in August 2014 (Baker et al., 2014). We would welcome for publication other examples of novel approaches to horizon scanning, risk assessment and prioritization as part of our mission to help share good practice and ideas around the EPPO Region.