| Elm yellows phytoplasma |
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| Introduction |
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Elm yellows (EY) or elm phloem necrosis, Phytoplasma ulmi, is a serious disease of elm (Ulmus) species caused by a bacterial like organism called a phytoplasma. Symptoms of plants infected with EY include leaf chlorosis (yellowing of leaves), leaf wilting, discolored inner bark, and death of trees. The phytoplasma is spread or vectored by the white-banded elm leafhopper, Scaphoideus luteolus or by root grafts.
EY was first reported on elm in Ohio in 1882. The phytoplasma is now known to occur in the following states and provinces in North America: Alabama, Arkansas, Georgia, Iowa, Illinois, Indiana, Kansas, Kentucky, Massachusetts, Minnesota, Mississippi, Missouri, Nebraska, New Jersey, New York, Ohio, Oklahoma, Pennsylvania, Tennessee, West Virginia, and Ontario. The disease is not known to occur in Oregon.
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| Regulations |
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A quarantine was established against Phytoplasma ulmi (phloem necrosis) and Ophiostoma ulmi (Dutch elm disease), in November 1976 under Oregon Administrative Rule (OAR) 603-052-0114 to stop the continued spread of the disease. In Oregon, the counties of Benton, Clackamas, Jackson, Lane, Linn, Malheur, Marion, Multnomah, Polk, Union, Washington, and Yamhill are under quarantine. All states and districts of the United States except Alaska, Arizona, Florida, Hawaii, Louisiana, New Mexico and Utah are also under quarantine. This quarantine prohibits entry of all parts of Ulmus sp. and related genera Zelkova and Planera into the state of Oregon from quarantined areas. Seed and tissue culture plantlets are exempt and allowed. All tools or equipment utilized in the pruning or disposal of infected commodities are also prohibited entry into the state of Oregon unless they are decontaminated by an approved method.
Elm and related genera from non-quarantined areas may be permitted entry into the state of Oregon if each lot or shipment is accompanied by a certificate issued by an official state agency. The certificate must include the state of origin and the kind and amount of commodities covered by the certificate. The certificate must also affirm that all such commodities are a product of the state from which shipped or of another state within which neither EY nor Dutch elm disease is known to occur, and that such commodities are free from the described diseases.
Commodities restricted within quarantine areas, with the exception of commercially produced nursery stock, are prohibited movement within or outside non-quarantined areas except for the transportation of such commodities to locations authorized by the department for the burning, burial, or other approved method of disposal thereof. All tools or equipment utilized in the pruning or disposal of infected commodities are also prohibited movement within or outside said areas unless they are decontaminated by an approved method.
Commercial producers of elm nursery stock in Oregon can apply for a director's exemption allowing them to import elm species from quarantined states. To qualify for the exemption, the plants must be kept in an insect proof screenhouse for one growing season and visually inspected by the nursery inspector for the presence of EY and Dutch elm disease. The plants must also be laboratory tested for elm yellows phytoplasma before being released from quarantine.
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