Bordeaux is a dormant season spray that is useful to combat fungal diseases and certain bacterial issues. It is a combination of copper sulfate, lime and water. You can purchase a prepared mixture or make your own Bordeaux fungicide preparation as you need it.
Fall and winter are the best times to protect plants from spring fungal problems with homemade Bordeaux mixture. Issues such as downy and powdery mildew, and black spot can all be controlled with proper application. Fire blight of pear and apple are bacterial diseases that can also be prevented with the spray.
Bordeaux Fungicide Recipe
All the ingredients are available at garden centers, and the recipe that follows will help with making Bordeaux fungicide. This recipe is a simple ratio formula that most home growers can easily master.
Copper fungicide is readily available as a concentrated or ready to use preparation. The homemade recipe for Bordeaux mix is 10-10-100, with the first number representing copper sulfate, the second is dry hydrated lime and the third water.
Bordeaux fungicide preparation weathers better on trees than many of the other fixed copper fungicides. The mixture does leave a blue-green stain on plants, so it is best to keep it off any that are near the home or fencing. This recipe is not compatible with pesticide and can be corrosive.
Making Bordeaux Fungicide
Hydrated lime, or slaked lime, is calcium hydroxide and is used to make plaster among other things. You need to soak the hydrated/slaked lime before using it (dissolve it at 1 pound (453 g.) slaked lime per gallon (3.5 L.) of water).
You can start your Bordeaux fungicide preparation with a slurry of sorts. Use 1 pound (453 g.) copper in 1 gallon (3.5 L.) of water and mix it in a glass jar that you can seal.
The lime should be handled with care. Use a dust mask to avoid inhaling the fine particles when making Bordeaux fungicide. Mix 1 pound (453 g.) lime into 1 gallon (3.5 L.) of water and let it stand for at least two hours. This allows you to make a quick solution of Bordeaux.
Fill a bucket with 2 gallons (7.5 L.) water and add 1 quart (1 L.) of the copper solution. Mix the copper slowly into the water and then finally add the lime. Stir as you add 1 quart (1 L.) of the lime. The mixture is ready to use.
How to Make Bordeaux Fungicide in Small Amounts
For spraying in small amounts, prepare as above but only mix 1 gallon (3.5 L) of water, 3 1/3 tablespoons (50 ml.) of copper sulfate and 10 tablespoons (148 ml.) of hydrated lime. Agitate the mixture thoroughly before you spray.
Whichever type you use, make sure the lime is from this season. The homemade Bordeaux mixture needs to be used the day you prepare it. Make sure you rinse the Bordeaux fungicide preparation out of your sprayer with plenty of water, since it is corrosive.