The following diseases are quarantined against shipment into and within Oregon. Oregon also has several control areas designed to protect specific counties or designated areas from diseases and pests of regulatory concern that may exist elsewhere in the state. For more information on the state and federal regulations visit the Oregon Dept. of Ag., Plant Division website at:
Black Leg – This statewide quarantine requires all crucifer seed for planting in the State of Oregon be tested and found free of black leg [Leptosphaeria maculans (asexual stage = Phoma lingam) and Leptosphaeria biglobosa] prior to planting. See Section 4 of this handbook for disease description and treatment information.
Blueberry Scorch Virus – see Section 4 of this handbook for more information.
Chestnut Blight – See Section 4 of this handbook for more information.
Dutch Elm Disease – see Section 4 of this handbook for more information.
Eastern Filbert Blight – Strains of Anisogramma anomala from eastern North America can overcome the single dominant resistance gene bred into new cultivars of C. avellana. There are new restrictions on commercial and ornamental hazelnut cultivars imported from out-of-state (OAR 603-052-0825). See Section 4 of this handbook for more information.
Elm Yellows – see above (Oregon’s Most Unwanted: Invasive Species) for more information.
Grape quarantine – Grape plants and cuttings may be imported only if produced in sterile soilless media and must be free of grapevine fanleaf virus, grapevine leafroll-associated viruses, grapevine corky bark disease agent, grape phylloxera, vine mealybug, European grapevine moth, and Xylella fastidiosa (Pierce’s disease). Plants and cuttings must be officially tested for Pierce’s disease using an approved method prior to importation.
Hop quarantine – Hop quarantine covers hop powdery mildew, arabis mosaic viruses, Hop stunt viroid, ilarviruses, and Verticillium wilt. See Section 4 of this handbook for more information.
Pierce’s disease – Xylella fastidiosa – This disease, which has been a high-profile and rapidly increasing disease in California and Southern States, is not known to be in the Pacific Northwest. Our climate may be too cold for the pathogen to survive. The disease is in Florida and Texas and can be very damaging. A new, more efficient vector (the glassy-winged sharpshooter) has been found in California. Unlike the blue-green sharpshooter this new insect is not restricted to riparian areas. The presence of the glassy-winged sharpshooter is having a huge impact on producers in southern California. Several glassy-winged sharpshooters were found near western Oregon ornamental nurseries in 2000. An extensive survey that fall of 291 samples from vineyards, native hosts, and nurseries did not find any evidence of the causal bacterium.
Oak Wilt Disease – see above (Oregon’s Most Unwanted: Invasive Species) for more information.
Peach Yellows Phytoplasma – The disease has not been found on the west coast but was a problem early last century in east coast states of North America. It can be transmitted by grafting and by the plum leafhopper. Leaves are chlorotic, yellow, and often roll upward; red spotting develops as leaves begin to droop. Severe infections will develop slender shoots with small, narrow, yellow leaves. Buds that are normally latent on younger trees produce dwarfed leaves. Terminal dieback is common in one-year-old shoots. Trees usually die 2 to 3 years following the appearance of symptoms. Fruits are of poor quality and tend to reach maturity three weeks earlier than normal. Red-colored cultivars have saturated coloration, which may be spotted. The flesh exhibits red streaks or marble patterns, with redness around the pit
Peach Latent Mosaic Viroid – Due to variety or strain differences infected plants seldom display obvious symptoms. In susceptible cultivars infected with the severe strain blotches of chlorosis appear in the early spring. Leaves are short, broad, and sometimes exhibit “wavy” margins. Shoot development is delayed, and buds can show necrosis and be cast; branches also become necrotic and die. Lower trunks become void of shoot growth. Internal necrosis (and stem pitting) can develop in susceptible cultivars contributing to premature aging of the trees. Fruits of sensitive cultivars infected with the severe strain are irregular in form, have indentations and bumps, and their size is considerably reduced. Sutures tend to crack and stones appear deformed and swollen. This quarantine is currently undergoing official review and may be repealed. Check website listed above for more information.
Peach Rosette Phytoplasma – The disease has not been found on the west coast but has been a problem in Southeast United States. It can be transmitted by grafting and an insect vector is suspected but unknown. Initial symptoms develop quickly. The first leaves reach normal size but become yellow and roll inward or arch backward, their veins sometimes appearing red. Defoliation of these leaves follows. Internodes of new shoots are extremely short with leaves pressed into dense rosettes. As leaves on older parts of the trees have already fallen, only tufts of young leaves on the tips of bare shoots remain. Blossoms rarely develop and/or the flowers do not set fruit on affected branches. Most diseased trees die within the first year of infection; those that leaf out the following spring die shortly thereafter.
Phytophthora ramorum – This pathogen is subject to state and federal quarantines as described earlier in Section 3 of this handbook. See “Oomycetes” in Section 3 for more information on diseases caused by Phytophthora.
Powdery Mildew of Hops – see “Fungi” in Section 3 of this handbook.
Rathayibacter toxicus – This bacterium has not been detected in Oregon, although its nematode vector Anguina funesta was found in 2010. The quarantine requires annual ryegrass and other susceptible seed imported from areas where the bacterium is known to occur to be officially tested and found free of the bacterium prior to importation. It also mandates mitigation measures should the bacterium ever be detected in the state.
Small Broom-rape (Orobanche minor) see “Clover—Clover Broom-rape” in Section 4-C of this handbook for more information on this noxious weed that is also a plant pathogen.
The following diseases are quarantined against shipment out of Oregon. Most of the information on these diseases can be found in Section 4 of this handbook. For more information on the state and federal regulations visit the Oregon Dept. of Ag., Plant Division website at:
Burrowing Nematode on tropical plants.
Black Stem Wheat Rust Disease on barberry and Oregon grape.
Camellia Flower Blight.
Chestnut Bark Disease and many others.
Dutch Elm Disease.
Verticillium wilt on hops or mint.
White Pine Blister Rust on all gooseberry and currant plants.
Brooming Disease of Walnut.