ILLUSTRATIONS OF TREE
DISEASES
FOLIAGE DISEASES OF DECIDUOUS TREES
- PREMATURE DEFOLIATION.
THIS IS PAGE 2 OF 3.
This page shows types of
defoliation which is caused by leaf infections.
There are 7 pictures; scroll down the page to see them
all.
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SYMPTOMS of FOLIAGE
DISEASES
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A
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A common foliage disease of elms is
BLACK LEAFSPOT, caused by
Stegophora ulmea. Infections
develop as small dark spots which may or may not
show a chlorotic halo. If there are many spots,
the whole leaf may yellow and drop
prematurely.
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Another leaf disease that often causes
defoliation is RUST of poplar and
cottonwood caused by Melampsora medusae.
In this picture, the trees on the left are
susceptible to rust and have been defoliated.
The trees on the right are a rust- resistant
cultivar.
Photo courtesy of Vernyl
D. Pederson
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SEPTORIA LEAFSPOT is widespread
and serious on many different plants. Different
species of this fungus are HOST-SPECIFIC,
limited to infecting one plant genus or
family.
On Cottonwood, individual spots are tiny but
numerous.
Photo courtesy of James A,
Walla
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SEPTORIA LEAFSPOT causes
premature defoliation.
Most of the lower leaves of these young
cottonwoods have been lost to
Septoria.
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SEPTORIA LEAFSPOT causes
premature defoliation.
An entire row of Caragana in this
shelterbelt has been defoliated by this
disease.
Photo courtesy of James A. Walla
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SEPTORIA LEAFSPOT.
On raspberry (Rubus), the Septoria
lesions are irregular with darker margins.
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LEAF BLIGHT.
In some diseases, the individual leaf spots may
COALESCE or spread together. This has happened
on these green ash (Fraxinus) leaves with
Mycosphaerella blight.
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© RWS 22 August '99
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These images are provided for the personal use of students, scholars,
and the public.
Any commercial use or publication of them is strictly prohibited.
The images included in these collections were scanned from slides
used by Professor R. W. Stack in his course, Tree Diseases (PltPath
456), at North Dakota State University. All of the images are
original photographs, mostly taken by Prof. Stack. A few pictures are
borrowed and are included here by permission and with
acknowledgement. The images are organized according to the course
syllabus.
The images were scanned and processed by the author at the Multimedia
Resource Center, North Dakota State University, Fargo, ND 58105.
Prepared by Robert W. Stack
NORTH DAKOTA STATE UNIVERSITY
Original 25 Sept 96, this version 22 August 1999. Revised 30 April
2001.
TO COMMENT: rstack@ndsuext.nodak.edu