Bacillus Subtilis Strain Used To Control Diseases

Ken Rudisill Horticulture Faculty Bay County krru@ufl.du

A new organic disease control product will be on the shelves this spring. The product will be labeled for ornamentals, lawns, vegetables and fruits. It is made from a strain of bacteria called Bacillus subtilis.

Bacillus subtilis is a naturally occurring bacterium that is commonly found in soil, water, air, and decomposing plant material. Under most conditions, however, it is not biologically active and is present in the spore form.  Bacillus subtilis strain QST 713 controls the growth of certain harmful bacteria and fungi, presumably by competing for nutrients, growth sites on plants, and by directly colonizing and attaching to fungal pathogens.

The B. subtilis strain QST 713 is a naturally occurring strain that was isolated in 1995 from soil in a California peach orchard. This product is applied to foliage. It is not considered a genetically modified organism.

The B. subtilis strain QST 713 is approved for use on a wide variety of food crops, including cucurbits, grapes, leafy vegetables, peppers, potatoes, and tomatoes.It is also labeled for ornamentals, trees, shrubs and lawns.

Target pests include fungi and bacteria that cause scab, rust, powdery mildew, downy mildew, dollar spot, brown patch, and early leaf spot, early blight, late blight, and bacterial spot.

No harmful health effects to humans are expected from use of B. subtilis strain QST 713.  Be sure to read the label and follow the EPA guide lines for the use of personnel protective equipment.  This will help to insure the safety of the applicator.

At this time there are no adverse effects expected to non-target organisms, the exception being honey bees.  To reduce the risk to honey bees, applicators are not allowed to spray areas where bees are actively foraging.