{"id":611,"date":"2022-12-01T23:21:30","date_gmt":"2022-12-01T23:21:30","guid":{"rendered":"https:\/\/blogs.oregonstate.edu\/southcoastfieldforest\/?p=611"},"modified":"2022-12-02T22:31:18","modified_gmt":"2022-12-02T22:31:18","slug":"suspect-sudden-oak-death-what-you-need-to-know","status":"publish","type":"post","link":"https:\/\/blogs.oregonstate.edu\/southcoastfieldforest\/2022\/12\/01\/suspect-sudden-oak-death-what-you-need-to-know\/","title":{"rendered":"Suspect Sudden Oak Death? What you need to know."},"content":{"rendered":"\n

By Norma Kline, OSU Forestry Agent, Coos and Curry Counties<\/p>\n\n\n

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Figure 1. Quarantine areas<\/figcaption><\/figure>\n<\/div>\n\n\n

If you have read news articles about Sudden Oak Death (SOD) in southern Oregon\u2019s Curry County you may be concerned that trees on your property are at risk for infection. Sudden Oak Death has killed hundreds of thousands of tanoak since it was first detected near Brookings in 2001. Why has Sudden Oak Death been so damaging to our native ecosystems? Sudden Oak Death is caused by an introduced (non-native) pathogen called Phytophthora ramorum. Phytophthora ramorum<\/em> is an internationally quarantined pathogen first described in California in the mid-1990\u2019s and remains a serious threat to forest and nursery industries. Oregon\u2019s interagency Sudden Oak Death program actively surveys and treats infestations at the leading edge of the disease.<\/p>\n\n\n\n\n\n\n\n

Phytophthora ramorum<\/em> spreads easily in the rainy and windy climate in southern Oregon. The disease advances across the landscape as spores on the foliage of infested tanoak spread to healthy tanoak. Spores are sometimes blown for several miles in windy conditions. Infested tanoak die within 1-2 years and often seem to die \u201csuddenly\u201d. If you are located near known infested areas (Figure 1) keep a close eye on symptoms of the disease on tanoak trees and other host species. The potential for a Sudden Oak Death infestation on your property increases the closer in proximity you are to an infested area. Early detection and treatment of Sudden Oak Death are important tools to help slow the spread of this disease across the landscape. Even if you are located outside of Curry County and any known area of infestation, it\u2019s still important to monitor your forest for unusual forest health issues.<\/p>\n\n\n

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Figure 2. Darkened petioles on tanoak leaves. \u00a9 Norma Kline, OSU.<\/figcaption><\/figure>\n<\/div>\n\n
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Figure 3. Shoot blight symptoms on evergreen huckleberry. \u00a9 Norma Kline, OSU.<\/figcaption><\/figure>\n<\/div>\n\n\n

Common symptoms to look out for on tanoak include a darkened petiole (leaf stem) (Figure 2), tip blight, and bleeding at the trunk. Look for leaf and shoot blight symptoms on rhododendron, evergreen huckleberry, madrone, Oregon myrtle and salal (Figure 3). Shoot dieback symptoms might be observed on Douglas-fir, grand fir, and coastal redwood. While there are many host species known to show symptoms of SOD, Tanoak is the primary host for Sudden Oak Death in Oregon.  Oregon white oak (Quercus garryana<\/em>) has not been found to be susceptible. California black oak (Quercus kelogii<\/em>) and canyon live oak (Quercus chrysolepis<\/em>) are host species that can develop cankers and die, at this time these two species have not been found to be infested with Phytophthora ramorum<\/em> in Oregon.<\/p>\n\n\n\n

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How to Identify Tanoak<\/strong><\/p>\n\n\n\n

Tanoaks (Notholithocarpus densiflorus<\/em>) are a cousin to our true oaks (true oaks are in the genus Quercus<\/em>). Tanoaks are evergreen (not deciduous) and have acorns like a true oak, but their acorn caps have bristles (Figure 4). Tanoak leaves are thick and leathery with a fuzzy underside (Figure 5).<\/p>\n<\/div><\/div>\n\n\n\n

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Figure 5. Tanoak leaves. \u00a9 Pat Breen, OSU.<\/figcaption><\/figure>\n<\/div>\n\n
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Figure 4. Tanoak acorns have distinctive bristles on caps. \u00a9 Pat Breen, OSU.<\/figcaption><\/figure>\n<\/div>\n\n\n

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What do you do if you suspect symptoms?<\/strong><\/p>\n\n\n\n