Agriculture Reference
In-Depth Information
and copper in different formulations. Bordeaux mixture, for example, is a sulfur and cop-
per spray that has been used for many years in vineyards. (Because copper and sulfur are
elemental, fungi do not develop resistance to them.) You will find these products in vari-
ous forms, typically powdered, liquid, or granules. Sometimes the active ingredient is com-
bined with other ingredients, such as oils or spreader/stickers. These may help the active
ingredient to adhere to the grapevines, or may have some antifungal action of their own.
In general, waiting to see mildew spores on your leaves means that you have left it too
late to start spraying that year. Fungal spores almost always overwinter on the ground or in
the plants and then are released by spring rains and rising temperatures, and their growth
is often encouraged by humidity. The time to start most spraying programs is before or
around bloom, and then you must continue to reapply every week or two. You may wish
to try different products and to alternate products. As your vineyard grows, you will settle
on a schedule for spraying in response to your experience, and then vary it according to the
conditions.
Bordeaux mixture is a traditional spray used to control fungal diseases. It is used
in organic vineyards around the world.
There are also some bacterial and viral diseases that affect grapevines. Although bac-
terial diseases can be controlled with various measures, your best defense against viral dis-
eases is to buy only certified virus-free stock. Controlling pests that spread diseases—such
