Discard infected plants. Red Pigments by Arlene Hoskins. Powdery mildew is a fungal disease that is evident as a white or grey coating on the leaves of plants. Begonia leaves are turning brown on the edges and dying. They are glucosides (carbohydrates) that are dissolved in the cell sap, which is the fluid in the cell vacuole. Begonia categories include tuberous-rooted, rhizomatous and fibrous-rooted varieties. A few days later leaves on the first plant started to shrivel and take on the appearance of ancient parchment. I've recently become interested in rex begonias and I've acquired a few different plants over several months. Mosaic, malformed leaves, pale yellow ring spots, severe chlorotic mottling of leaves or plant stunting may occur. Begonia Maculata. Begonias grow well in partially shaded, humid areas with moderate temperatures. woodii. Plant … I recently planted out my begonia plants that I started off from tubers. On the other hand, you must NOT keep any begonia too wet. However, most of them have crispy brown leaf edges. They looked fine when they first went out a week ago but now some have leaves that have gone limp and are turning white though they are all in new compost to which Miracle Grow and crystals to retain water have been added. Purchase plants free of symptoms. The silvery-white polka dots look almost unreal as if they were painted onto the deep olive-green leaves. The same thing happened to the other begonias that … Home > Begonian > Volume 70 (March/April 2003). This will cause rotting to occur and also invite various diseases that begonias can be prone to including powdery mildew, among others. According to Cornell University, powdery mildew can affect a begonia's … 10 years ago. Impatients necrotic spot, tobacco ring spot, broadbean wilt, cucumber mosaic, tobacco necrosis virus. Although many plants can handle a powdery mildew infestation, the fungus can cause serious injury to begonias. To read more about crispy brown leaves in houseplants in general, be sure to read my blog post on why plant leaves turn brown and crispy. Without any doubt, the Begonia maculata is one of the prettiest Begonia plants I have ever seen.. Begonias are tropical plants known for their waxy flowers and varicolored leaves. Pink, red or purple color in leaves is caused by the presence of pigments called anthocyanins. Begonia plants come in many varieties and hybrids, in different colors, sizes, and shapes.