Sunday, May 23, 2021

Third year of 5-year 36 experimental fern planting: "Ground Zero" ferns still thriving

In February 2018, we planted 3 lines of nursery sword ferns, 12 plants per line,  hypothesizing that those planted into Ground Zero (GZN, GZS) would survive, but that those planted into (actually just ahead of) the active die-off zone (ADZ) zone would not do well.  All 36 plants have been watered through three summers.  The prediction continues to hold: 

ADZ: 5/12 ferns dead, 2 are marginal, 5 healthy
GZS: 1/12 ferns dead, 11 healthy
GZN: all 12 ferns are healthy
t.test pvalue, likelihood of this difference occurring by chance: 8.7e-4

We surmise that the presumed pathogen no longer resides at Ground Zero - but could possibly return.  A continuous dense population of affected sword ferns may be needed for reinfection: the GZ sword ferns may be "socially distant" from current areas of active die-off.

5 comments:

  1. Glad to have found your blog. We live in a woods in Fall City and have become concerned about the number of good sized sword ferns that are blackened and dead this year. In one area there is a line of dead ferns and a big, old rhody all dead despite being watered regularly last summer.
    What's going on? What can we do?

    ReplyDelete
  2. Thank you for the report - and sorry to hear about your ferns. We like to allow for the possibility (we sometimes see this) that very dry weather leads to frond death, but the full plant recovers the followingt spring. Which suggests we cannot judge your ferns till next May.

    We are gathering up some funding and local experts (WSU and UW and the community) to figure out strategies to identify the pathogen which most of us think is the likely cause.

    Meanwhile, tracking the spread is helpful. Perhaps you could send some photos and GPS coordinates? They could then go (if you agree) on a regional map like this one for Tiger Moutain: https://paulshannon.shinyapps.io/issaquahAlpsMap/

    ReplyDelete
  3. This comment has been removed by a blog administrator.

    ReplyDelete
  4. This comment has been removed by a blog administrator.

    ReplyDelete
  5. This comment has been removed by a blog administrator.

    ReplyDelete