Phragmites reed grass for Mason Bee tubes

Phragmites in estuary/marsh
Last years stems of Phragmites in estuary/marsh being harvested for mason bee tubes. It is important that this is done only before new shoots start to emerge.  I have a theory that this native Phragmites exists in this marsh only because the marsh was fenced in the early years to prevent grazing by cattle and sheep. It has been eliminated from most of the other marshes in BC by grazing (personal communication with Robert Prescott-Allen). The reason this marsh was fenced was that the plant Triglochin maritima  (Sea arrow grass) grows in the marsh and it is toxic to grazers.

(http://metchosinmarine.ca/gf/triglochin-maritima/)

“Seaside arrow-grass (Triglochin maritima) is a native plant found sporadically across Canada in saline, brackish, or fresh marshes and shores. This plant contains cyanogenic glycosides, which can release HCN during mastication by animals. Poisoning occurs primarily with ruminants, including cattle and sheep. The concentration of toxic chemicals increases during times of moisture depletion (Majak et al. 1980, Cooper and Johnson 1984, Poulton 1989).”