Express PRA for Diplocarpon mali Y. HARADA & SAWAMURA
The fungus Diplocarpon mali (anamorph: Marssonina coronaria) occurs in Italy since 2003, since 2010 in Germany (Hesse and Baden-Württemberg) and since 2011 in Austria and Switzerland. It is assumed that the fungus has established in different parts of Baden-Württemberg, the actual spread in Germany is not known. Possibly the fungus had already established before and only got conspicuous because of the very humid weather conditions during the last three summer periods. The main host plant is Malus spp., but also Chaenomeles is described as a host plant in the literature. The fungus may cause severe early defoliation. Thereby the trees are weakened and thus the sprouting and fruit development are reduced in the subsequent year. Up to now mainly organic apple plantations and scrab resistant varieties are concerned, presumably because for those rarely/no fungicides are used. Severe damage is reported from Korea. In nurseries, damage can be limited by usual fungicides against apple scrab (Venturia inaequalis) and by means of hygienic measures and removal of infested foliage. The fungus is naturally spread via conidiospores and ascospores via wind and water. An introduction with nursery stock is possible when leaves remain on the plant. Based on this risk assessment it has to be assumed that the fungus Diplocarpon mali will establish further, spread and cause severe damage in Germany and other EU Member States. In general, measures to control and prevent the further spread of Diplocarpon mali should meet § 4a of the PBVO, however it is questionable whether such measures against a further spread were effective and practicable. Measures against the natural spread are only effective and useful in case that the infestation would only occur in very few locations to a very limited extent. Presumably this is not the case. Thus the infestation would have to be surveyed specifically.
|Pest Risk Analysis||Download||456,44kB|