Response to new published Forest Research led study on cut Sitka spruce

This was the first UK reported case in the forest of Ips typographus breeding in Sitka spruce stems. However, the vulnerability of all Picea species was already well understood (hence the plant health restrictions on all spruce in the demarcated area), and indeed there were already laboratory tests and field evidence from continental Europe that Sitka spruce can be infected by Ips typographus (like all other spruce). 

John Bruce, Confor National Manager for England, covered this story last year, pointing out that it had been assumed Ips can infest Sitka spruce in the UK forest environment, while also noting that it reinforces the threat this pest poses to our forest industry. This latest published study led by Forest Research also affirms what is known already.

That said, the study will also hopefully start to build understanding of how trees can defend themselves against this pest, which is very welcome as it could help inform future pest management options.

Sitka spruce growing in the drying climate of SE England is perhaps one of the most vulnerable Picea species for drought stress. Sitka is relatively rare in this region, and we have not yet seen evidence of Ips impact on live standing Sitka spruce trees.

Ips remains a massive threat to our forest industry and while we cannot be complacent, there are a couple of areas that may well give us time to make forests more resilient in the core spruce zones and find suitable alternatives to give more productive options to Sitka spruce.

Firstly, Ips outbreaks continue to be managed within the demarcated area (which was extended following the East Anglian outbreaks) and the evidence still suggests all Ips outbreak sources are from continental blow over, rather than spreading within the UK. There are also responsible measures being undertaken by FC around spruce planting restrictions and proactive spruce removal to further reduce risks of the endemic spread of this pest through the UK.

Secondly, Forest Research and University of Cambridge recently published a paper on the Phenology of the spruce bark beetle in the UK under past, current and future climate conditions. In models modified from the continent, this shows us that while the climate in SE England is mild enough to host two generations of Ips, upland forests (particularly in Scotland) are unlikely to support one annual generation due to insufficient thermal warming within a season.

Ips is a serious pest, and it is critical that all spruce growers remain vigilant and check the health of spruce trees on their land, identifying stressed, fallen, and snapped trees and taking action to remove them and any surrounding susceptible material. Please report signs of Ips via the Tree Alert portal.