Powdery mildew is a fungus affecting various backyard garden plants, including vegetables, fruits, ornamental plants, and roses. It is caused by various species of fungi, which produce powdery white or gray patches on plants’ leaves, stems, and flowers. These patches can reduce the plant’s ability to photosynthesize and eventually lead to stunted growth and decreased yield.
In this guide, we’ll cover the key strategies for managing powdery mildew in the home garden, including preventative measures, monitoring and identification, organic fungicides, and good gardening practices. By following these strategies, gardeners can effectively control powdery mildew and keep their plants healthy and thriving.
How to Manage Powdery Mildew in Home Garden
Disease Cycle of Powdery Mildew
Powdery mildew overwinters in mycelial mats and can survive in resting spores. In the spring, infected buds release conidia that spread to new host tissue. The fungus grows and reproduces rapidly, producing new conidia that can be carried by wind or other means. Secondary infections may occur, and the fungus may enter dormancy at the end of the growing season or produce resting structures for overwintering. Unlike many other fungi, powdery mildew conidia do not require free moisture to germinate.
Garden Plants Which Are Affected by Powdery Mildew
- Ornamental plants such as roses, dahlias, zinnias, phlox, and lilacs.
- Vegetables such as artichokes, beans, beets, carrots, cucumber, eggplant, lettuce, melons, parsnips, peas, peppers, pumpkins, radicchio, radishes, squash, tomatillo, tomatoes, and turnips.
- Fruits such as apples, grapes, strawberries, and raspberries.
- Herbs such as basil, chives, mint, and rosemary.
Symptoms of Powdery Mildew Attack on Home Garden
- White powdery spots: Plants infected with powdery mildew may have circular, powdery white spots on leaves, stems, and fruit.
- Upper surface of leaves: The powdery mildew usually covers the upper part of the leaves but can also grow on the undersides.
- Yellowing leaves: Young foliage is most susceptible to damage. Infected leaves turn yellow and dry out.
- Disfigured leaves: The fungus might cause some leaves to twist, break, or become disfigured.
- Spreading spots: The white spots of powdery mildew will spread to cover most of the leaves or affected areas.
- Disfigured growth: Leaves, buds, and tips can also become disfigured, especially late in the growing season.