Mildews are one of the most widespread and easily recognized fungi. They are common on phlox, lilac, melons, cucumbers, and many other plants. Mildew forms a white to grayish powdery growth, usually on the upper surfaces of leaves. Small black dots appear and produce spores that are blown by wind to infect new plants. Leaves will become brown and shrivel when mildew is extensive. Fruits ripen prematurely and have poor texture and flavor. To control mildews, prune or stake plants to improve air circulation and dispose of infected plants before spores form. Apply bicarbonate sprays to prevent the spread of infection.