I assume it's Russian Knapweed.
http://www.nwcb.wa.gov/weeds/russian-knapweed
I'm also surprised that they would wait to spray until the plants are full grown for the season as it's much more effective in the spring on juvenile plants.
http://www.nwcb.wa.gov/weeds/russian-knapweed
I'm also surprised that they would wait to spray until the plants are full grown for the season as it's much more effective in the spring on juvenile plants.