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We Got Mildew Yes We Do! We Got Mildew, How ‘Bout You?

September 16th, 2010
Here is an example of squash with just a few spots of powdery mildew.

 As tends to happen in the late summer, our squash is suffering from powdery mildew.  This problem is pretty easy to identify;  our plants will look like someone tossed some baby power all over them.

It starts small and then just gets worse if left to proliferate.  Powdery mildew sends little tubes into leaf cells to suck out their contents, killing the cells in the process. As leaf cells die and the leaf’s surface becomes covered in the white fungus, photosynthesis is reduced and leaves may be lost. Crop volume and eating quality can be reduced.

Here the mildew has been left to keep growing!

So how do you get rid of it organically?  Well, there are quite a few options. 

According to our own UC Davis Integrated Pest Management, prevention is always the best way to avoid this problem.  In other words, if your garden is prone to this kind of issue, next time you plant squash, melon, pumpkin, etc., be sure to start with a resistant variety.


You can avoid powdery mildew my making sure your plants receive plenty of sun.  (Because of the location of these plants near the South Building of the Robert Mondavi Institute, these plants do get more shade than others.)  Also be sure to:

  • Provide good air circulation by not crowding your plants
  • Rotate squash beds on a minimum three-year cycle to reduce the chance of a fungal buildup or reinfection from one year to the next.
  • Pull up infected plants and burn or bury them.

We got the dummy whammie–the plants need more sun and they are not disease resistant varieties–so now what?

According to UC Davis Integrated Pest Management, once you have the powdery mildew problem, oils, like neem oil,  tend to work better at eradicating the issue once you have it rather than preventing the problem. 

You may also want to try a biological fungicide like Serenade Disease Control Concentrate, but like UC Davis Integrated Pest Management states, “While this product functions to kill the powdery mildew organism and is nontoxic to people, pets, and beneficial insects, it has not proven to be as effective as the oils or sulfur in controlling this disease.”

For those of you interested in home remedies, it seems that you can also try making your own spray of one part skim milk to 9 parts water.  Skim milk works just as well as other types of milk–whole, low fat etc., but no fat means no odor!  Read more about this research finding here:  Using Milk to Control Powdery Mildew.

Did you get the gift of powdery mildew this summer?  If so, what did you do to get rid of it?  Let us know!


Herb “forts” and other companion plantings

September 10th, 2009

In her summer garden tour, our gardener Arlene describes the configuration of the plantings in specific beds as herb “forts.” This clever name refers to the protective barrier created around different varieties of vegetables; the herbs create a protective barrier because they either repel or attract harmful or beneficial insects. Companion plants can also be effective for other reasons; for example, plant sunflowers next to beans because beans enjoy the partial shade provided by the sunflowers’ foliage. To download the pdf of Arlene’s Summer Garden Tour visit our website and click on the link to the tour on the homepage.

Specifically in our garden this summer, Arlene discusses the English thyme/garlic chive “forts” that have been planted around the yellow crookneck and rĂªve scallopini squashes. Thyme is a beneficial companion plant because it helps to control whitefly which can be harmful to squash, and because garlic chives contain the same essential oil as garlic, its smell is displeasing to aphids, flies, and mosquitoes. The photo below shows the yellow crookneck squash surrounded by the garlic chives.

The other benefit to utilizing companion planting in your garden is that it decreases the need for pesticides or herbicides. Companion planting is a critical aspect of organic gardens. According to Kelle Carter of Seeds of Change, “Organic gardening is composed of numerous aspects that make up a whole interconnected system. This system relies upon insects, birds, shade, sun, and all other aspects of a living and working community. By growing numerous types of crops you create habitats for beneficial insects or animals, deter problem pests, and enrich your soil to create a living ecosystem of beneficial bacteria and helpful fungi.” Read Carter’s article about companion plants here; the article is an excellent overview and also includes a chart of plants, their companions and their effects.

You can also visit the Good Life Garden website for detailed information about the crops we have planted currently. We provide information about companion planting and pest management, nutritional information, historical facts, and how to plant, grow and prepare the edibles in your garden.