AGU Fall Meeting: Mistletoe is ‘kiss of death’ to drought-stressed trees

11 December 2017


Included in this announcement:

  1. Research from the AGU Fall Meeting: Mistletoe is ‘kiss of death’ to drought-stressed trees
  2. Today’s press events
  3. Additional press conference: The September 2017 Tehuantepec and Puebla earthquakes in Mexico
  4. New plenary session added: Perspectives and priorities on Earth and space science at four U.S. federal agencies
  5. Noteworthy sessions happening today
  6. Potentially newsworthy presentations
  7. Online media resources

Please visit the 2017 Fall Meeting Media Center to view previous media advisories and press releases that include important information about press registration, badge pickup, press conferences, quiet rooms, searching the scientific program, and AGU On-Demand.

1. Research from the AGU Fall Meeting: Mistletoe is ‘kiss of death’ to drought-stressed trees

A dense mistletoe broom (Amyema miquelii) has successfully established itself as the terminal structure of the branch of a Eucalyptus tree (E. moluccana) in an Australian eucalypt woodland.
Credit: Anne Griebel.

NEW ORLEANS — Around the holidays, a sprig of mistletoe over a doorway is festive and romantic. But mistletoe has a sinister side: The parasitic plant can sometimes kill the very tree it depends on for food by robbing its host of water during dry spells, according to new research being presented here.

There are about 1,600 known species of mistletoe around the world, all of which sink their roots into trees and shrubs, and extract water, carbon and nutrients from them. Mistletoes are an important part of the ecosystems where they live, but can sometimes create problems for their hosts. Trees with too much mistletoe growing on them can become less healthy and even die when the weather is hot and dry for too long.

“It’s not a bad thing to have as part of an ecosystem,” said Anne Griebel, a plant researcher at Western Sydney University in Richmond, Australia, who will be presenting new findings about mistletoe on Monday, December 11 at the 2017 American Geophysical Union Fall Meeting in New Orleans. “But if you have too much it can cause death to trees.”

It’s well-known that mistletoe can kill trees, but it’s not been clear exactly how the parasite harms its host, said Griebel. She and her colleagues suspected that mistletoe lacks the ability to adjust and conserve water during dry, hot weather, causing its host tree to lose too much water.

To verify this, Griebel and her team equipped two species of Eucalyptus trees with instruments that measure how sap – and therefore water – flows in trees infested and not infested with mistletoe. They also compared the rates of sap flow between branches on the same trees – those branches with only mistletoe leaves and those without mistletoe.

A sensor used to monitor the tree’s water flow through the stem of a Eucalyptus fibros tree (commonly known as ‘red ironbark’ due to hardy and deeply fissured bark that accumulates on the trees).
Credit: Anne Griebel.

As expected, during the hottest, driest weather, the Eucalyptus trees adjusted to the conditions by closing the small pores on their leaves, called stomata, to minimize transpiration and conserve water. This dramatically slows the sap flowing through the host branches, helping the tree to conserve water.

However, the researchers found that despite the hot weather, the rate of sap flow on mistletoe-infested branches did not slow down to conserve water. The mistletoe lacked the adaptation for hot, dry weather that the Eucalyptus trees had. The mistletoe just kept living the high-life, drawing water and nutrients from the Eucalyptus trees.

This led water to be lost from the mistletoe leaves at a much higher – and sometimes unsustainable – rate compared to the water loss from the Eucalyptus leaves. This higher rate of evaporation could eventually damage the trees’ water transport system and cause the Eucalyptus trees to die, Griebel said.

It was as if the trees had sprung a leak, Griebel said.

“The Eucalyptus trees definitely have a very effective way of shutting down,” she said. “Stem-to-stem you can see pretty clearly the difference between those with and without mistletoe.”

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Notes for Journalists
Lead researcher Anne Griebel will give an oral presentation about this research on Monday, 11 December at the 2017 AGU Fall Meeting.

Talk title:
Mistletoe infection alters the transpiration flow path and suppresses water regulation of host trees during extreme events

Session:
B11K: Understanding Plant and Ecosystem Function Across Scales Through the Lens of Plant Hydraulics I

Date: Monday, 11 December 2017
Time: 9:45 – 10:00 a.m. CST
Location: Morial Convention Center, Room 386-387
Abstract number: B11K-08

Contact information for the researcher:
Anne Griebel, Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia: [email protected], +61 468834149 (please email first)

Related paper: http://iopscience.iop.org/article/10.1088/1748-9326/aa8fff

2. Today’s press events

9:00 a.m. – Evolution of a new Pacific island may unlock secrets to Mars
10:30 a.m. – Assessing flood risk in the U.S. and the consequences of sea level rise
11:30 a.m. – Eclipse 2017: Studying the Sun-Earth connection and more from the Moon’s shadow
1:45 p.m. – Dan Rather (Media Availability)
2:30 p.m. – The biggest story in the solar system: Science from NASA’s Juno mission to Jupiter
4:00 p.m. – Climate change has unexpected consequences for animal populations
5:00 p.m. – American Geophysical Union leaders (Media Availability)

All Fall Meeting press events take place in the Press Conference Room, Room 346-347. They will also be streamed live on the AGU press events webpage and archived on AGU’s YouTube channel. Slides and other materials will be available in the Virtual Press Room on the Fall Meeting Media Center.

3. Additional press conference: The September 2017 Tehuantepec and Puebla earthquakes in Mexico

The AGU Public Information Office has scheduled an additional press conference on the September 2017 Tehuantepec and Puebla earthquakes in Mexico. The press conference will take place at 12:30 p.m. CT on Wednesday Dec. 13 in the Press Conference Room, Room 346-347. Details for the newly added press conference are below and in the “Press Conferences” tab in the Fall Meeting Media Center.

The September 2017 Tehuantepec and Puebla earthquakes in Mexico
Wednesday, 13 December
12:30 p.m.

The September 8th and 19th, 2017, Tehuantepec and Puebla earthquakes were some of the largest and most damaging earthquakes ever recorded in Mexico. The Mw 8.1 earthquake (Sept. 8) affected several million people and was widely felt across central and southern Mexico, while the Mw 7.1 event (Sept. 19) produced strong ground motions in big cities in central Mexico leading to numerous building collapses and large numbers of casualties. This panel will discuss the recent events, including new information related to Mexico’s early warning systems and linkages between the two earthquakes.

Participants:
Ross Stein, Temblor, Inc., Redwood City, California, U.S.A.;
Xyoli Perez-Campos, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico;
Juan Manuel Espinosa Aranda, CIRES Center of Instrumentation and Seismic Record and SASMEX Mexican Seismic Alert System, Mexico City, Mexico.

Sessions: S32D, S33G

4. New plenary session added: Perspectives and priorities on Earth and space science at four U.S. federal agencies

A special plenary session titled “Perspectives and Priorities on Earth and Space Science at Four U.S. Federal Agencies – NOAA, NASA, USGS, and NSF” has just been added to the 2017 AGU Fall Meeting scientific program.

The plenary session will take place on Thursday, 14 December from 9:00 – 10:00 a.m. in the La Nouvelle C ballroom of the New Orleans Ernest N. Morial Convention Center.

In this session, a panel of some of the highest-ranking officials at U.S. science-based federal agencies – NASA, NSF, NOAA, and USGS – will present their views on the state of science at their agencies, their priorities for the near future and how science will fare in an era of increasing budget pressures. AGU president Eric A. Davidson will moderate the panel.

Panelists include:
Thomas Zurbuchen (Invited), associate administrator for the Science Mission Directorate at NASA headquarters in Washington, D.C. and professor of space science and aerospace engineering at the University of Michigan in Ann Arbor, Michigan;
William Easterling, head of the Directorate for Geosciences at the National Science Foundation and dean of the College of Earth and Mineral Sciences at Pennsylvania State University in University Park, Pennsylvania;
RDML Tim Gallaudet, USN Ret., Assistant Secretary of Commerce for Oceans and Atmosphere and Acting NOAA Administrator in Washington, D.C.;
William H Werkheiser, acting director of the U.S. Geological Survey in Reston, Virginia.

Registered journalists who are interested in attending this session should meet an AGU staff member at the entrance to the La Nouvelle C ballroom 30 minutes prior to the start of the session. Journalists can also stream the lecture live on AGU On-Demand.

5. Noteworthy sessions happening today

Presidential Forum Lecture
Veteran journalist Dan Rather will deliver the Presidential Forum Lecture from 12:30 – 1:30 p.m. in the New Orleans Theater, located on the second floor of the Morial Convention Center above Hall I-1. Registered journalists who are interested in attending this talk should meet an AGU staff member at the entrance to the lecture hall 30 minutes prior to the start of the talk. Journalists can also stream the lecture live on AGU On-Demand. A media availability will be held immediately following the lecture in the Press Conference Room, Room 346-347.

6. Potentially newsworthy presentations happening today

Sessions

  • Creating Inclusive and Diverse Field and Lab Environments Within the Geosciences
    Session U12A, 10:20 a.m. – 12:20 p.m., Room E2
  • Induced Seismicity in the United States and Canada
    Session S13D, 1:40 – 3:40 p.m., Room 217-219
    Session S14A, 4:00 – 6:00 p.m., Room 217-219

Abstracts

7. Online media resources

For journalists: During the Fall Meeting, journalists can find many resources online in the Virtual Press Room in the Fall Meeting Media Center. These resources include press releases, press conference materials and other information. Videos of press conferences will be added to the Virtual Press Room during the meeting for easy online access.

The AGU press office also offers two online tools to connect reporters with scientific experts at the 2017 Fall Meeting. The Find an Expert tool allows reporters to view a list of scientific experts who are available for interviews at the meeting. The Request an Expert tool allows reporters to send requests for experts directly to PIOs. These tools are now available online in the Fall Meeting Media Center.

For public information officers: PIOs are now able to share press releases and other materials in the Virtual Press Room by directly uploading them via the Press Item Uploader. PIOs can upload press releases, tip sheets and press conference materials to the Virtual Press Room at any time before or during the meeting, including uploading items in advance and scheduling them to post during the meeting.

The AGU press office also offers two online tools to connect reporters with scientific experts at the 2017 Fall Meeting. The Find an Expert tool allows public information officers to list scientific experts who are available to be interviewed by reporters at the meeting. The Request an Expert tool allows reporters to send requests for experts directly to PIOs. PIOs who wish to receive expert request emails from reporters should fill out the Receive Expert Requests form. More information about these tools can be found in the Fall Meeting Media Center.

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AGU Contact:

Nanci Bompey
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Lauren Lipuma
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AGU Fall Meeting Press Room:
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