Agriculture Reference
In-Depth Information
Organic Fungicides and Bactericides
Organic fruit growers have relatively few fungicides and bactericides avail-
able to manage fungal and bacterial diseases. At the time of writing, the Or-
ganic Materials Research Institute listed only 29 fungicidal products.
Sulfur and copper have long been the staple materials for organic disease
control, used alone or blended together. They attack pathogens at multiple
sites on the fungal spores, which accounts for their effectiveness against a
wide range of diseases.
Sulfur
Sulfur is among the oldest fungicides and has been used since antiquity. It
remains the most important organic fungicide, particularly for such diseases
as apple scab. Sulfur fungicides can be applied as dusts or sprays and are
used to control a wide variety of diseases, primarily those caused by fungi.
Plant tissues can be damaged or killed by sulfur, and phytotoxicity is
common on sensitive tissues, increasing at higher temperatures. Foliar ap-
plications of sulfur-containing products at temperatures above about 80°F
(27°C) can cause phytotoxicity. Note that sulfur can also harm beneficial or-
ganisms. When used excessively or at the wrong time of the growing season,
sulfur can be particularly harmful to predatory mites that help manage plant
parasitic mites. Sulfur is a valuable component to plant protection, but it is
not a silver bullet. Use it cautiously and no more than absolutely needed.
CAUTION!
Sulfur is toxic to apricots. Apply fixed coppers instead.
