Borage is not just decorative but also is used in cooking and for alternative herbal remedies. This plant, native to the Mediterranean, has hairy leaves and bright blue, star-shaped flowers. It is also known for attracting wildlife. Borage is a multifaceted member of your garden, but if it develops white spot disease on its leaves or flowers, it will not only make your yard look unattractive, it will not be useful in your culinary and healing efforts, either. According to the Backyard Gardener, white spot disease on borage is likely powdery mildew, which is fairly easy to control once you know the problem.
Borage plants have green leaves that are bristly and hairy, and blue flowers. Powdery mildew starts out as small, white spots on the leaves or flowers. Left unchecked, the symptoms will spread and the spots will become bigger, creating a mat of mildew. As the mildew continues to grow, the white spots will develop small, black spores in the center.
When your plant gets powdery mildew, there will not be too much physical hardship on the plant. The most obvious evidence will be white spots on leaves and flowers. But if powdery mildew spreads to cover entire leaves or petals, then the plant may get mushy or start to wilt.
White spots on your borage plants generally indicate that your plant is not getting enough sun, that the air circulation around the plant is insufficient and creating a humid environment conducive to mold and mildew growth or that you are watering your borage and the rest of your garden incorrectly. Removing the affected growth should help prevent the spread of the problem, and the unaffected parts of the plant can still be used for curative and culinary purposes.
To deal with powdery mildew, you need to use sterile pruning to remove affected leaves and flowers. Wipe the blades of your clippers or shears with rubbing alcohol after every snip, which prevents you from accidentally spreading the disease when you are cutting off affected parts of the plant. Once you have removed all affected parts, dispose of them in a garbage bag. Monitor the plant for recurring white spots, and remove newly affected foliage immediately.
Preventing white spot disease in borage is relatively simple. Since the plant tolerates partial shade to full sun, you should be able to grow in areas that get plenty of sunlight, which makes it less likely that powdery mildew will be able to take hold. Also, water your borage using a drip hose to keep moisture off leaves and flowers, and do so in the early morning rather than afternoon or evening.