- We had the hope that the second generation would go down into the ground and winter, they chose instead to swarm during the month of July / August, says Mattias Sparf, forest consultant and damage coordinator at the Forest Board in Östergötland.
Östergötland is one of the counties most affected by attacks. After last year's dry and hot summer, the extent of this year's injuries can be at least as large or greater in their quarters.
- The forest owners and professionals in the forest I talked to in the county say that there is at least as much attack and some say it is twice as much, says Mattias Sparf.
After last summer's drought when the attacks were great, the firs are still stressed and more susceptible.Major attacks 2019
- My view is that there is more attack in 2019 than 2018, says Mattias Sparf.
Detecting the latest attacks requires careful inventory as they are not visible in places.
- The spruces are still green in the direction you have to go close and look for drill flour at the stem base, says Mattias Sparf.
Despite a softer and cooler summer, the second generation of fir bark drills seems to cause relatively large damage.
- Looking at SMHIS weather data, we have had warmer temperatures than normal during the summer. In addition, at the end of July, there were a few days with really high temperatures and that's when the new generation of bark drills swarmed. In addition, there have been major local differences, seen in the rain.
Granbarkborren's swarm 2019 comparison between catch results and temperature in three control traps outside Linköping. Photo: Source: Mattias Sparf forest consultant and damage coordinator at the Forest Board in Östergötland
How problematic is the situation?
- If you look at the overall situation, it is worrying and it is something we will be working on more for years to come, says Mattias Sparf.