{"id":32745,"date":"2025-03-27T09:30:01","date_gmt":"2025-03-27T13:30:01","guid":{"rendered":"https:\/\/www.purdue.edu\/fnr\/extension\/?p=32745"},"modified":"2025-08-05T11:07:35","modified_gmt":"2025-08-05T15:07:35","slug":"smooth-patch-of-oak-purdue-landscape-report","status":"publish","type":"post","link":"https:\/\/www.purdue.edu\/fnr\/extension\/smooth-patch-of-oak-purdue-landscape-report\/","title":{"rendered":"Smooth Patch of Oak – Purdue Landscape Report"},"content":{"rendered":"

Purdue Landscape Report:<\/em><\/a> These oak trees are showing the symptoms of smooth patch ( see below Figures 1, 2, 3).\u00a0 This condition is the result of a fungal infection that is restricted to the outer bark, causing it to slough off. The bark layer remaining is smoother and lighter in color than uninfected, normal bark.<\/p>\n

Patches can vary from a few inches to a foot or more in diameter and may occur on branches as well as the trunk.\u00a0 Several fungi can cause this condition. A common species, Aleurodiscus oakesii<\/em>, produces clusters of flat, disc-like spore-bearing structures on the surface of the smooth bark. These structures are gray or beige in color and are usually less than 1\u20442 inch in diameter (Figure 4).<\/p>\n

The best time to see this interesting phenomenon in the forest is during wet periods in late winter before new spring growth begins, when the light gray bark stands out in the light penetrating the canopy. The fungal structures shrink when dry so will be more apparent following rainy weather.<\/p>\n

\n
\n

\n\"Figure
\n<\/a>
Figure 1: Smooth patch symptoms beginning to merge on trunk of white oak.<\/figcaption><\/figure>\n<\/div>\n
\n

\n\"Figure
\n<\/a>
Figure 2: Lower trunk of white oak with smooth patch symptoms.<\/figcaption><\/figure>\n<\/div>\n<\/div>\n

 <\/p>\n

The fungal structures may be mistaken for wood decay fungi, but because smooth patch fungi invade only the nonliving, outer bark tissues, they do not affect the health of the tree. No control measures are needed.<\/p>\n

\n
\n
\n

\n\"Figure
\n<\/a>
Figure 3: Isolated area of smooth patch near base of white oak.<\/figcaption><\/figure>\n<\/div>\n
\n

\n\"Figure
\n<\/a>
Figure 3: Isolated area of smooth patch near base of white oak.<\/figcaption><\/figure>\n<\/div>\n<\/div>\n<\/div>\n

 <\/p>\n

The fungal structures may be mistaken for wood decay fungi, but because smooth patch fungi invade only the nonliving, outer bark tissues, they do not affect the health of the tree. No control measures are needed.<\/p>\n

Resources:<\/strong>
\nIndiana Forestry & Woodland Owners Association (IFWOA) YouTube Channel<\/a>
\nDistrict Forester<\/a>, Indiana DNR Division of Forestry, for over 10 acres of woodlands
\nDirectory of Professional Foresters<\/a>, Indiana Forestry & Woodland Owners Association (IFWOA)
\nIndiana Woodland Steward E-newsletters<\/a>, Eleven Member Organization
\nThe Nature of Oaks Webinar<\/a>, Purdue Extension-FNR YouTube Channel, Shared from Indiana Forestry & Woodland Owners Association
\nPurdue Arboretum Explorer<\/a>
\nNative Trees of the Midwest<\/a>, Purdue University Press
\nA Woodland Management Moment<\/a>, Playlist, Purdue Extension \u2013 Forestry and Natural Resources (FNR) YouTube Channel
\nConservation Tree Planting: Steps to Success<\/a>, Purdue Extension \u2013 FNR YouTube Channel
\nForest Improvement Handbook<\/a>, The Education Store
\nWoodland Stewardship for Landowners<\/a>, Playlist, Purdue Extension \u2013 FNR YouTube Channel
\nID That Tree<\/a> \u2013 Video Playlist, Purdue Extension \u2013 Forestry and Natural Resources (FNR) YouTube Channel
\nInvasive Species<\/a>, Playlist, Purdue Extension \u2013 FNR YouTube Channel
\nInvasive Plant Species Identification<\/a>, Video, Purdue Extension \u2013 FNR YouTube Channel
\nReport Invasive Species<\/a>, Purdue Invasive Species
\nSubscribe<\/a>\u00a0\u2013 Purdue Extension-FNR YouTube Channel<\/p>\n

Tom Creswell<\/a>, Plant & Pest Diagnostic Laboratory Director
\nPurdue Botany and Plant Pathology<\/p>\n","protected":false},"excerpt":{"rendered":"

Purdue Landscape Report: These oak trees are showing the symptoms of smooth patch ( see below Figures 1, 2, 3).\u00a0 This condition is the result of a fungal infection that is restricted to the outer bark, causing it to slough off. The bark layer remaining is smoother and lighter in color than uninfected, normal bark. […]<\/p>\n","protected":false},"author":62,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[80,53,54,622],"tags":[60,913,504,408,71,1182,72,495],"class_list":["post-32745","post","type-post","status-publish","format-standard","hentry","category-trees","category-urbanforestry","category-wildlife","category-woodlands","tag-forestry","tag-fungal-disease","tag-oak","tag-trees","tag-urban-forestry","tag-white-oak","tag-wildlife","tag-woodlands","audience-for-enthusiasts","audience-for-homeowners","audience-for-landowners","audience-for-professionals"],"acf":[],"aioseo_notices":[],"publishpress_future_action":{"enabled":false,"date":"2026-04-16 10:23:53","action":"change-status","newStatus":"draft","terms":[],"taxonomy":"category","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/32745","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/users\/62"}],"replies":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/comments?post=32745"}],"version-history":[{"count":15,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/32745\/revisions"}],"predecessor-version":[{"id":34711,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/32745\/revisions\/34711"}],"wp:attachment":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/media?parent=32745"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/categories?post=32745"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/tags?post=32745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}