Abstract Detail

Poster Session

McTavish, Christine Kay [1], Fulbright, Dennis W [2], Jarosz, Andrew M [1].

Emerging epidemic: correlation of Phomopsis spp. with spruce decline in the Lower Peninsula of Michigan.

Recently, landscape spruce trees have experienced a sudden increase in the incidence and severity of branch death, tip blight, and needle drop symptoms throughout the lower peninsula of Michigan.  While known spruce diseases cause a few of these symptoms individually, no known pathogen causes the full range of symptoms that characterizes the current epidemic on both juvenile and mature trees that we are calling spruce decline.  Decline begins at the bottom of a tree and spreads upward, starting with the loss of needles more than a year old on a branch, and progresses through the death of lateral shoots until the whole branch dies.  Curiously, there are no outward signs of pathogen infection.  Only when the top layer of bark is removed can cankers be found on dying branches.  In 2013, a survey of these infected branches was conducted at 24 sites across the Lower Peninsula of Michigan. Over 400 cankers were sampled at these sites with 8 trees sampled per site, one branch per tree was collected, and isolates were obtained from at least two cankers per branch.  The most commonly isolated potential pathogens from cankers were Phomopsis spp. (48%), followed by Diplodia sp. (26%).  In contrast, Cytospora kunzei, the spruce pathogen already known to kill branches, was isolated from only 2% of the cankers.  Future work includes identifying Phomopsis and Diplodia to species using DNA sequencing of the ITS region, as well as Phomopsis disease screening trials that will determine the level of susceptibility within and among various spruce species.

1 - Michigan State University, Plant Biology, 612 Wilson Rd, 143 Plant Biology, East Lansing, MI, 48824, USA
2 - Michigan State University, Plant, Soil, and Microbial Sciences, 612 Wilson Rd rm 158, East Lansing, MI, 48824, USA

Keywords:
Phomopsis
spruce decline
survey.

Presentation Type: Offered Paper - Poster
Session: P6
Location: Lincoln Room/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 8:00 PM
Number: P6011
Abstract ID:159
Candidate for Awards:Graduate Student Poster Presentation Award