Symptoms. Powdery mildew, Erysiphe lagerstroemiae , on crape myrtle shoot. - Knowledgebase Question. Powdery Mildew - Euonymus Powdery Mildew. 0. The surfaces of leaves are covered with irregular patches or a thin layer of grayish white powdery mildew. What you describe sounds like a fungal disease called powdery mildew. Plants are notorious for powdery mildew; place in full-sun location with good air circulation to avoid it. Question by ramonalponce June 3, 2010. A 2009 study by the University of Connecticut concluded that milk is just as effective than chemical applications (if not moreso) when it comes to treating powdery mildew. New York, Ne. In late summer, tiny black dots are scattered over … ... Several diseases can also affect euonymous shrubs, including cankers, spots caused by fungus and powdery mildew. Answer from NGA June 3, 2010. Powdery mildew is a common disease on many types of plants and is prevalent under the diverse conditions found in many areas of California. White patches of powdery mildew on euonymus leaf. via Couleur/pixabay.com. It's in white powdery spots on the leaves. https://www.wikihow.com/Get-Rid-of-Powdery-Mildew-on-Plants Even though there are several types of powdery mildew fungi, they all produce similar symptoms on plant parts. ... conditions, but they're pest prone and susceptible to scale, thrips, and spider mites. How do I cure white mold on euonymus? Tropical Plants. Species Euonymus alatus and its selections take sun or shade. This may sound like a surprising solution, but milk is an extremely effective powdery mildew treatment. The infected leaves are yellow and may drop prematurely. Verticillium wilt is a disease that often shows up with sudden die-back of one large branch, or 1/2 of the plant. Description. Euonymus 'Manhattan' die back. In Colorado, powdery mildews are common on ash, lilac, grape, roses, turfgrass, vegetables (such as cucurbits and peas), euonymus, cherry, apple, crabapple, pear and Virginia creeper, among others.