Elm yellows is a plant disease of elm trees that is spread by
leafhoppers or by root grafts.
Elm yellows, also known as elm
phloem necrosis, is very aggressive, with no known cure.
occurs in the eastern United States, and southern
Ontario in Canada.
It is caused by phytoplasmas which infect the phloem (inner bark) of
the tree. Similar phytoplasmas, also known confusingly as 'Elm
yellows', also occur in Europe. Infection and death of the phloem
effectively girdles the tree and stops the flow of water and
nutrients. The disease affects both wild-growing and cultivated trees.
6 See also
Elms are very important to the American landscape, prized for their
unique shade characteristics. Most native elms are susceptible to elm
yellows and there are few resistant cultivars. Large, healthy,
landscaped elm trees can easily be worth thousands of dollars.
Penn State University
Penn State University is home to one of the oldest and largest elm
stands in the country. Penn State has been battling Dutch elm disease
for many decades, and the recent introduction of elm yellows into the
Penn State campus poses many threats. A tree near the university
president’s house had to be removed and numerous trees in State
College, Pa have died or have been removed due to elm yellows.
Elm malls across the US are at risk of being destroyed by elm yellows.
Cornell University, for example, had a large elm collection which was
being managed for Dutch elm disease, much like Penn State, but once
elm yellows had spread to the campus, all of the elms were destroyed
within a matter of years.
In North America the disease is transmitted from infected to healthy
trees by the whitebanded elm leafhopper (Scaphoideus luteolus Van
Duzee), the meadow spittlebug (
Philaenus spurarius) and by another
leafhopper (Allygus atomarius), although other insects are also
suspected of being vectors. Transportation of nursery trees is another
way for elm yellows to be spread over long distances. As leafhoppers
move very slowly so movement of elm yellows has been slow.
When an elm is infected with elm yellows, the root hairs die. The
phytoplasma infection then moves up the bark and infects the phloem,
depriving the tree of nutrients. Death of the phloem essentially
strangles the tree. As the phloem is infected, it will change color
and take on a wintergreen smell, similar to that of black birch or
The crown, top of the tree turns yellow all at once, it can occur from
July till September, when the leafhoppers are active.  It turns
yellow from a lack of nutrients to the top of the tree.
Aggressive control is needed if trees show symptoms of being infected.
Time is of the essence since nearby trees may already be infected.
Removal and destruction of the infected tree is the first step,
followed by trenching around the next two rows of trees near it to
isolate infection. Spraying trees with insecticide will also help
reduce the chances of transmission by leafhopper. Injecting trees with
tetracycline antibiotics has been shown to slow the progress of elm
Tetracycline inhibits protein synthesis by preventing tRNA from
attaching to the Ribosome. 
Phytoplasma bacteria do not have a Cell
wall  Since
Elm yellows and other phytoplasma do not have cell
walls, most antibiotics will not be effect, this is why tetracycline
and antibiotics that target internal functions of the cell are needed.
^ a b c d "
Elm Yellows." Elmcare.Com. 19 Mar. 2008
^ a b Price, Terry. "Wilt Diseases." Forestpests.Org. 23 Mar. 2005. 19
^ Conti, M., D'Agostino, G., Mittembergher, L. (1987) A recent
epiphytotic of elm yellows in Italy. Proceedings of the 7th Congress
of the Mediterranean Phytopathological Union, 208–209. Consejeria de
Agricultura y Pesca de la Junta de Andalucia, Granada, Spain
^ a b Ruskin, Paul. "Penn State Prepares for '
Elm Yellows' Disease."
PSU Live 12 Nov. 2007.19 Mar. 2008
^ "How to Differentiate Dutch
Elm Disease From
Phloem Necrosis" US
Forest Service. 1981. Accessed: May 29th 2016
^ "Antibiotics." Elmhurst.edu. 30 May 2016.
^ Jacqueline Fletcher and Astri Wayadande. "Fastidious
Vascular-Colonizing Bacteria." apsnet.org. 2002. Accessed: 30 May