Investigating pine mortality management prescriptions in Flanders

Scots pine is dominant or significantly present in about half of Flemish forests and is aspect-defining in some habitat types and regionally important biotopes (RBB).

In 2018, we noticed candle wax-like resin efflorescence on trunks of Scots pine in Ophovenderheide (Oudsbergen) and in Rijckevelde (Bruges). Dutch colleagues also saw similar phenomena in the Netherlands-Germany border region. After analysis, it turned out to be a distant state of infestation by the fungus Sphaeropsis sapinea.

After some further reading and contacts with German and French colleagues, it appears that general increasing pine mortality is assumed, perhaps even similar to that of Norway spruce. Pines are weakening, causing fungi like Sphaeropsis to behave much more aggressively. But we also see other infestations emerging. On young pines, for instance, common pine shoot beetle, on mature trees Chalcophora mariana, ... And others are on their way from southern Europe.

Meanwhile, 2022, we have to note that in forests like De Stropers (Stekene) and Pietersembos (Maasmechelen) about a third of Scots pines show clear signs of infestation or have died.

However, these are all secondary infestations. Further research into the underlying causes is needed and we are exploring what additional management prescriptions are possible.