{"id":2723,"date":"2019-05-09T00:04:11","date_gmt":"2019-05-09T07:04:11","guid":{"rendered":"https:\/\/depts.washington.edu\/hortlib\/pal\/pal-question-514\/"},"modified":"2023-08-03T16:30:43","modified_gmt":"2023-08-03T23:30:43","slug":"powdery-mildew-and-euonymus","status":"publish","type":"pal","link":"https:\/\/depts.washington.edu\/hortlib\/pal\/powdery-mildew-and-euonymus\/","title":{"rendered":"Powdery mildew and Euonymus"},"content":{"rendered":"

Have you heard about a problem with Burning Bush<\/strong>
\n(Euonymus alatus) getting a mildew this year? The<\/strong>
\nleaves have turned yellow green with small spots of<\/strong>
\nlighter yellow discoloration.<\/strong><\/p>\n

 <\/p>\n

Powdery mildew is a common and usually not life-threatening
\nproblem with Euonymus. Make sure the plant has good air
\ncirculation, and be sure to clean up and destroy fallen
\nleaves which are infected. However, the symptoms of this
\nfungal problem would be whitish coating on the leaves, rather
\nthan yellowed leaves. This makes me wonder if it is a
\ndifferent problem such as scale (which is actually an
\ninsect). Check and see if there are small bumps on the leaves
\nor stems. Scale can cause yellowed leaves. If your plant has
\na small infestation, you can try scraping the scales off with
\nyour fingernail, prune out the most infested parts of the
\nplant, and then apply dormant oil to the trunk and branches
\nbefore growth starts next spring, or apply superior oil
\nduring the growing season. There are also other fungal and
\nbacterial problems that could be causing the spots.<\/p>\n

See this fact sheet from Penn State<\/a> for more on Euonymus scale.<\/p>\n

Here<\/a> is an archived link to additional information, which comes from
\nUniversity of Illinois Extension. Excerpt:<\/p>\n

Burning bush (also called Winged Euonymus): Euonymus alatus<\/p>\n

Cold injury – Winter injury may be caused by very low
\ntemperatures as well as drought stress. With excessively low
\ntemperatures, the moisture in the cells freezes (due to
\nchemical compounds in plants, moisture freezes at various
\ndegrees below freezing). Drought stress already has resulted
\nin limited moisture in the plant cells. Dry, freezing winds
\nduring the winter reduces the moisture level even farther,
\noften resulting in dead plant tissue. Diseases can help
\nmagnify or increase susceptibility to winter kill. Nectria
\ncanker kills the sapwood tissue thus reducing or even cutting
\noff moisture to tissue further out on the plant. Winterkill
\nalso makes plants more prone to infectious diseases and
\ninsect problems.<\/p>\n

Dieback\/canker – See bridal wreath spirea. In addition
\nBotryosphaeria dothidea will infect and kill for similar
\nreasons.<\/p>\n

Winged euonymus scale – Lepidosaphes yanagicola occasionally
\noccurs in the southern half of Illinois on burning bush. It
\nis an armored scale. And will attack several trees as well.
\nThis scale can cause premature leaf drop, branch die back and
\ncause the plant to become more prone to winter injury. It is
\nfound between the “wings” – the bark ridges. It does not move
\nto the plant’s leaves. The scale over winters as an adult and
\nlays its eggs in June. Eggs may be laid for up to a month.
\nMating occurs before frost.<\/p>\n

Euonymus scale – Unaspis euonymi – females are black and
\nmales are white. The scale causes the foliage to develop
\nyellowish green spots. Heavy infestation results in early
\nfoliage drop and often stems are killed. Eggs survive by over
\nwintering in the female body. The eggs hatch about early June
\nin Northern Illinois. Crawlers emerge and move onto new
\ngrowth or can be blown by wind to other plants.<\/p>\n

Since I cannot diagnose the problem remotely, it makes sense
\nto take plant samples to a Master Gardener Clinic.<\/p>\n","protected":false},"excerpt":{"rendered":"

Have you heard about a problem with Burning Bush (Euonymus alatus) getting a mildew this year? The leaves have turned yellow green with small spots of lighter yellow discoloration.   Powdery mildew is a common and usually not life-threatening problem with Euonymus. Make sure the plant has good air circulation, and be sure to clean up and destroy fallen leaves which are infected. However, the symptoms of this fungal problem would be whitish coating on the leaves, rather than yellowed…<\/p>\n

Continue reading Powdery mildew and Euonymus<\/span><\/a><\/div>\n","protected":false},"author":4,"featured_media":0,"menu_order":0,"template":"","keyword":[446,89,670],"class_list":["post-2723","pal","type-pal","status-publish","hentry","keyword-euonymus","keyword-insect-pests-control","keyword-scale-insects"],"acf":[],"_links":{"self":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/pal\/2723"}],"collection":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/pal"}],"about":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/types\/pal"}],"author":[{"embeddable":true,"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/users\/4"}],"wp:attachment":[{"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/media?parent=2723"}],"wp:term":[{"taxonomy":"keyword","embeddable":true,"href":"https:\/\/depts.washington.edu\/hortlib\/wp-json\/wp\/v2\/keyword?post=2723"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}