It may also kill young twigs. Spores landing on the treated leaves or fruit die, but the effect lasts only a short time. How to treat it: There are many ways to treat White Powdery Mildew but most gardeners prefer natural and organic methods. Julie Thompson-Adolf is a master gardener and author with 13+ years of experience with year-round organic gardening, seed starting and saving, growing heirloom plants, perennials, and annuals, and sustainable and urban farming. Well, the baking soda will increase the pH levels on the leaf surface. Appropriate mixing of the solution ensures that it is safe for plants, soil, and water systems. Plants with leaf spots or browning leaf margins are soap-sensitive, so you should cover them before treating your lemon tree. If you know which plants are susceptible, spraying them weekly with the baking soda/soap recipe (and reapplying after rain) can greatly reduce the incidence of powdery mildew in your garden. It is less effective as a cure once the fungus has taken hold. Lemons in coastal areas are most likely to contract gray mold. Then spray the mixture onto your plants to help organically kill powdery mildew traces. This is an old, trusted way to combat powdery mildew . This year, I discovered that a simple solution of baking soda in water is effective enough to mitigate powdery mildew growth on zucchini, butternut squash and pie pumpkin leaves. Powdery mildew is one of the most commonly occurring plant problems. It is a fungal disease that affects plant leaves and stems, coating them in what looks like a white or gray powder-like substance. This is an example of how and why myths get started. Apply the solution to a small portion of each plant's leaves, and check the sprayed areas the following morning. Sprays That Control the Japanese Plum Tree Diseases, How to Spray Phosphoric Acid on Grape Vines, Cal Poly San Luis Obispo Urban Forest Ecosystems Institute: Lemon, Growing a Greener World: Controlling or Eliminating Powdery Mildew, University of California Statewide Integrated Pest Management Program: Powdery Mildew on Ornamentals, University of California Statewide Integrated Pest Management Program: Citrus Diseases and Disorders of Fruit, University of California Statewide Integrated Pest Management Program: Botrytis Rot (Gray Mold), Kern County Rose Society: Powdery Mildew Control, University of California Yolo County Cooperative Extension: Foiling the Fungus Fairy, Bachman's: Horticultural Oil and Insecticidal Soap, University of Florida IFAS Extension: Citrus Problems in the Home Landscape, How to Treat Apple Scabs on Red Flowering Crabapples, How to Spray Fruit Trees in the Home Garden. The balmy summer days that make thoughts of freshly squeezed lemonade so appealing have a definite downside for lemon trees (Citrus limon). Water your lemon tree and any surrounding plants that might be hit by overspray. Introducing "One Thing": A New Video Series, The Spruce Gardening & Plant Care Review Board, The Spruce Renovations and Repair Review Board, 1/2 teaspoon of liquid, non-detergent soap. Powdery Mildews. Thoroughly coat leaves, branches and stalk until they are dripping. To control powdery mildew on plants, mix together the following: Pour the mix into a sprayer, and evenly coat all areas of the plant, including the underside of leaves and stems. Wear protective eyewear and a respiratory mask, a washable long-sleeved shirt, long pants and a hat while working with any fungicide. By using The Spruce, you accept our, Controlling Powdery Mildew With Baking Soda. If you know a plant is affected by powdery mildew year after year, as is the case with many monarda, phlox, and lilacs, then spraying early in the season may prevent any occurrence that year. Spraying soils that surround infected plants also help get rid of fungal spores that are soil-borne and hidden in surrounding dirt. Mix one tablespoon per quart of water and apply with a spray bottle. It can even affect the flavor of fruit and reduce blooms on plants. While there are chemical remedies for powdery mildew, few home gardeners need to use them; these controls usually are reserved for commercial farming operations. Powdery mildew only spreads on plant surfaces with pH readings lower than 7.0. Spray any susceptible plants located nearby, too.. Search If you are seeing powdery-looking patches on the foliage of your plants, you most likely have a case of the very common powdery mildew fungal disease.