Jun 25, 2010 - Difficulties, because you don't see these early symptoms during routine checks. ... Thank you for your attention. &. Happy Birthday FPL Madison.
The Massaria disease of planes: fine structure of the decay mechanism in xylem tissue of branches Uwe Schmitt Benjamin Lüer, Dirk Dujesiefken, Gerald Koch, Jörg Fromm von Thünen-Institute / vTI Institute of Wood Technology and Wood Biology & University of Hamburg Department of Wood Science & Institute of Arboriculture Hamburg/Germany
Madison, 25 June 2010
Content • Background of the Massaria disease • Symptoms - on the bark - in the xylem
• Wood decay - light microscopy - electron microscopy - UV-microscopy
•Conclusions
Madison, 25 June 2010
Background
- Plane is a frequently planted city tree because of its resistance against drought and air pollution
Madison, 25 June 2010
Background
Plane trees along streets and walkways In some cities in Germany about half of the planted trees are plane (Mannheim, Cologne)
However, in recent years frequently a dieback of branches was observed Madison, 25 June 2010
Background •The fungus
Splanchnonema platani is causing this disease.
•Early name of the fungus:
Massaria platani
•Fungus is usually a parasite of weak trees and known to be involved in natural pruning. •Well known from the Mediterranean area, but now spreads more and more to Central Europe. (fungus also occurs in the southern US states) North of the Alps, the Massaria disease was first found in 2003 in the south of Germany.
•Now also affects healthy trees. •Consequence of climate change??
Madison, 25 June 2010
Symptoms
Very early stage of infection: clearly visible pinkish discolouration along the upper side of branches. Difficulties, because you don‘t see these early symptoms during routine checks.
Madison, 25 June 2010
Symptoms Early stages of infection are characterized by a pinkish colour of the upper side of a branch.
About 90% of a branch affected by the fungus, decay symptoms less pronounced About 50% of a branch affected by the fungus with distinct decay symptoms
Madison, 25 June 2010
Symptoms
Advanced stages show a transition from pinkish to brown discolouration.
Madison, 25 June 2010
Symptoms
… and with continuing infection, the upper side of those branches appears black due to accumulation of spores. In Mannheim, a city in the south of Germany, about half of its 5000 plane trees show symptoms of the Massaria disease. Madison, 25 June 2010
Wood decay – Light microscopy Control xylem from an unaffected branch •Thick-walled fibres •Parenchyma cells with phenolic deposits •Thin-walled vessels
Xylem from an infected branch •Fibres in large areas show severe decay of their walls mostly with cavity formation •Middle lamellae still present although secondary wall nearly completely decayed •Vessel walls remain intact Madison, 25 June 2010
Wood decay – Electron microscopy Control
Parenchyma cells within decayed tissue remain structurally intact Cavity formation in fibre walls
Control
Fibre walls with nearly completely decayed secondary wall portions Vessel walls remain intact Madison, 25 June 2010
Wood decay – Electron microscopy
Spread of fungal hyphae through vessel lumens and pits
Growth of hyphae through pits was frequently observed between fibres. Madison, 25 June 2010
Wood decay – UV microscopy
Control tissue: scanning of xylem portions with a wavelength of 280 nm demonstrates the lignin distribution within different cell wall layers. Sections: epoxy resin-embedded, 1 µm thick Resolution: 0.25 µm x 0.25 µm Vessel
Highest lignin amounts in the cell corner regions, middle lamella regions, and vessel secondary walls. Fibre secondary walls show distinctly lower values. Madison, 25 June 2010
Wood decay – UV microscopy Decayed xylem: UV-scanning of those xylem portions with a wavelength of 280 nm clearly show a nearly unchanged lignin distribution in cell corner and middle lamella regions. •Secondary walls partly heavily degraded •Cavities frequently found •Vessel walls without visible decay symptoms •Resembles soft rot decay pattern Brown rot decay pattern should show a distinct modification of lignin distribution: -changes in cell corner and middle lamella regions should occur -increased absorbance in some cell wall regions due to modification of lignin should be observed Madison, 25 June 2010
Wood decay Vessel
Fibre
Obviously wound reactions are initiated But: time is too short to build up an effective protection & the fungus seems very aggressive. Madison, 25 June 2010
Conclusions •Massaria disease is a fungal disease of plane trees causing dieback of branches •Risc for the public safety because of cracking branches •First symptoms can be observed on the upper side of branches as pinkish discolourations of the bark; later affected branches show brown and black discolourations •Rapid spread of the hyphae through the bark into the xylem •Within the xylem, the hyphae preferably use vessels for penetration, but also are able to grow through pits •Decay pattern resembles more a soft rot decay •Lignin richer wall portions remain intact also in advanced decay stages, also lignin rich vessel walls •It appears possible that dry and hot summers are accelerating the spread of the fungus to central Europe Madison, 25 June 2010
Thank you for your attention & Happy Birthday FPL Madison
Madison, 25 June 2010
