elm yellows
{{Short description|Bacterial disease of elm trees}}
{{Infobox plant disease
| color =
| name = Elm yellows
| image = Elmphloemnecrosis.jpg
| caption = Symptoms of elm phloem necrosis
| common_names =
| causal_agents = Phytoplasmas
| hosts = Elms
| vectors = Leafhoppers (Scaphoideus luteolus, Philaenus spurarius, Allygus atomarius)
| EPPO_codes =
| distribution = Eastern United States and southern Ontario, Canada
| treatment = Tetracycline has been shown to slow down the disease
}}
Elm yellows is a plant disease of elm trees that is spread by leafhoppers or by root grafts."Elm Yellows." Elmcare.Com. 19 Mar. 2008
Importance
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 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.Ruskin, Paul. "Penn State Prepares for 'Elm Yellows' Disease." PSU Live 12 Nov. 2007.19 Mar. 2008
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.{{cn|date=November 2022}}
Transmission
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.{{cn|date=November 2022}}
Symptoms
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 birch beer.{{cn|date=November 2022}}
The crown, top of the tree turns yellow all at once, it can occur from July till September, when the leafhoppers are active."How to
Differentiate Dutch Elm Disease From Elm Phloem Necrosis" US Forest Service. 1981. Accessed: May 29th 2016
Control
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 yellows.
Tetracycline inhibits protein synthesis by preventing tRNA from attaching to the Ribosome."Antibiotics." Elmhurst.edu. 30 May 2016.
Phytoplasma bacteria do not have a Cell wallJacqueline Fletcher and Astri Wayadande. "Fastidious Vascular-Colonizing Bacteria." apsnet.org. 2002. Accessed: 30 May 2016.
See also
References
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