A great question came into Ask Gardenerd this week from Cathi Sowder:

Hi Christy,
I went looking for Serenade, an organic product for powdery mildew, from a past question & response in the Newsletter without success, finally finding out that was because it’s been discontinued! I want to use it on my grapevine whose developing grapes are frequently done in by powdery mildew, and I was looking for a better alternative to copper based products. Can you recommend another product currently available either on line or at nurseries or garden supply stores?

First off, good for you for avoiding copper fungicides. Copper persists in soils and binds up nutrients if overused in the garden. Serenade (and other biofungicides) uses bacteria that feed on the fungus instead of chemicals. So that’s our favorite approach to dealing with fungal infestations. Now on to the options:

It’s sad, Cathi, that Serenade is no longer available in consumer sizes. But there are alternatives available. The bummer is that they appear to only be available in gallon-sized bottles or larger!

• Serenade – 2.5 gallon – You CAN get serenade, but in a larger quantity. Go in on it with a friend or three and split the cost. Then mix and use what you need and store the container in a cool dark location. Keep in mind that this produce is PREVENTATIVE – which means that it’s not really effective once Powdery Mildew shows up.
• Cease – another bacterial-based biofungicide like Serenade but works once diseases show up. You’ll have to buy a gallon, but again, split with a friend or three.

Now let’s look at consumer-sized products:

• Bonide Revitalize – a biofungicide without copper spray (read the label carefully because Bonide makes a copper fungicide). This is the concentrated version but they do sell a Ready to Use option as well.
• Earth’s Ally Disease Control – available both in concentrate and ready to use options. It uses Citric acid to change the pH of surfaces which kills off pathogens. I’ve never used it, and am not sure how effective it is, but worth a try.
• Lost Coast Plant Therapy – we have a colleague who swears by this product. It works on bacterial and fungal infestations (with citric acid) and has other ingredients that combat diseases.

Give these a try and see how they work for you. As with all fungicides and disease-control products, make sure they are legal in your state and follow instructions for protection and ventilation.

Good luck, Cathi!