- UC Marin Master Gardener Events & Classes
- UC Marin Master Gardeners Opportunity Fund: Providing for the Future
Garden Help from UC Marin Master Gardeners
- Farmers Markets
- Help Desk
- Fire-safe landscaping
- Plants made for the shade
- Chinese pistache tree glows in autumn
- Attracting honey and native bees to your garden
- Sow wildflower seeds in fall for spring show
- Native shrubs create a visual anchor in landscapes - fast
- What to plant in the fall-winter veggie garden
- Proper pruning of wisteria produces a plethora of blossoms
- Compost for every corner of your spring garden
- Paying attention to mushrooms
- Inviting butterflies into the garden
- Growing in your garden now - blueberries
- What's the best way to plant a fruit tree?
- How to protect plants from frost
- What's that plant?
- Bright spots of color help lift the drabness of the winter garden
- Books for Marin gardeners
- Benefits of School Gardens
- Trees: not just nice to look at
- Dealing with mosquitos
- Epilobium – California fuchsia
- Why bees matter, and how you can help
- Picking the Right Plant for the Right Place in Your Garden
- What's That Plant?
- Keeping Cut Flowers Fresh
- Late Summer Color
- Growing Summer Squash
- Short on space? Containers to the rescue...
- Herbs: tough, attractive, practical
- These plants are true companions
- Companion planting in the vegetable garden
- Get Grounded – Healthy Soil Does Matter
- Mushrooms on the March
- Our Gentle Winters are Good for Vegetables
- Rodents like it Warm
- Know What Makes an Invasive Species Invasive
- California Natives - Plant Like a Native
- Consider a Simple Water-Catchment System and Rain Garden/Bioswale Before Winter Rains Arrive
- Have You Scheduled a FREE Bay-Friendly Garden Walk?
- A Green Autumn
- Rx for Pests: Ants
- Fine Tune Your Garden
- Colorful Drought-Tolerant Plants Thrive in Marin
- Water Restrictions and Recognizing Signs of Water Stress
- UC Researcher Is Helping Plants Survive the Drought
- Summer Is Perfect For Peppers
- Do the Leaves on Your Trees Look Scorched?
- Fine Tune Your Garden
- How to Recognize Drought and Water Stress
- Spring is the Time for Potatoes, Asparagus and Citrus
- Don't Let Stink Bugs... Bug Your Vegetables
- Harvesting Berries
- Water Heroes
- Natural Cold Storage
- Fruit Trees; Why We Treat Them in Dormancy
- Fondness for Old Friends
- What Happens to Garden Bad Guys in Winter?
- Plants that aren't blown away by the wind
- A hill o' beans
- Fruit tree thinning
- Fragrant plants: Add some chocolate or Kool-Aid to your garden
- Top 10 resolutions for Marin gardeners
- Trees with interesting bark shine in winter
- Who says your garden has to be green?
- Plant bulbs now for spring beauty
- Gardener's checklist for fall
- Cover crops boost soil in vegetable beds
- Rx: Living with deer
- Growing berries in Marin
- How to build healthy soil
- Gardener's checklist for summer
- Water-saving tips for the home garden
- Gardener's checklist for spring
- Stop the popping - Controlling hairy bittercress
- How to control aphids
- Brightening up the winter garden
- Selecting a fruit tree
- What to plant and harvest in the winter vegetable garden
- Rain, rain, don't go away
- Gardener's checklist for winter
- Getting rid of rats
- Fall: a time for planning and planting
- Asparagus: spears for years
- Lawn: use it or lose it
- Rx for powdery mildew
- Community Outreach Projects of UC Marin Master Gardeners
- Great Gardening Information
- Selecting Plants
- Marin Master Gardener Independent Journal Articles
- How to Become a Master Gardener
Rx for powdery mildew
If you’ve got white spots on your plants, there’s a good chance that it’s powdery mildew, a common, unsightly garden fungus that affects a wide variety of ornamentals and edibles. There is a common misconception that powdery mildew requires moist conditions. On the contrary, it typically proliferates in warm and dry areas such as those found throughout Marin. The perfect breeding ground for powdery mildew is a shady spot on a 60 to 80-degree day. Powdery mildew spores are carried by the wind, floating freely and invisibly throughout the garden.
Powdery mildew is usually more unattractive than it is serious. It typically first appears as white, powdery spots on leaves, shoots and sometimes flowers and fruit. Left unchecked, affected leaves may gradually turn yellow, die and fall off. Powdery mildew is most serious when it attacks vulnerable new growth, often causing disfiguring and dwarfing. Edibles with severe powder mildew infestations may have reduced yields and tasteless fruit. Susceptible plants include squash, cucumbers, beans, tomatoes, strawberries, grapes, roses, dahlias and zinnias. The growing tips of fruit trees also may develop the disease.
Getting rid of powdery mildew
Prevention is your best weapon against powdery mildew. Here’s how to avoid this fungus:
- choose resistant plant varieties
- plant in full sun
- avoid excess fertilizer
- provide good air circulation.
If powdery mildew manages to sneak into your garden, pick off and destroy the infected parts and spray infected plants with water early in the day. If this doesn’t do the trick, try applying neem or jojoba oil. If the fungus persists, you may want to try a sulfur or other type of fungicide. Some gardeners who have struggled with powdery mildew infestations in the past apply sulfur as a preventative. Follow package instructions closely.
To learn more, visit the following University of California Integrated Pest Management pages: Powdery mildew on vegetables and Powdery mildew on ornamentals.
Marie Narlock, Faith Brown, Nanette Londeree