Sunday, June 29, 2008

Nursery, Turf, Landscape, and Greenhouse - Microbial Pesticides

Microbial pesticides are products that control pests and diseases through the application of a live active ingredient. These active ingredients are microorganisms such as bacterial cells, fungal spores, etc. The following is general information on these materials and links to a good factsheet that lists the commercially available products.

Microbial pesticides have become much more available than in decades past for two reasons. Microbial pesticides can be considered natural (as long as the microorganism has not been genetically engineered), and so they are permitted for use in organic agriculture. Organic agriculture has grown substantially in recent years, creating market demand for these products.

Microbial pesticides are often perceived as safer to the environment than conventional chemical pesticides. For the most part, this perception is justified for several reasons: microbial pesticides are less toxic to non-target organisms (beneficial organisms, for example), more specific to target organisms (the pests and disease-causing pathogens), and often quicker to degrade than conventional chemical pesticides. However, because of these qualities, microbial pesticides may need to be applied more frequently than modern chemical pesticides, and simply running the tractor through the field frequently has its own environmental cost.

Plant pathologists from The Ohio State University have published a fact sheet on microbial pesticides, entitled Microbial Biopesticides for the Control of Plant Diseases in Organic Farming, available online at This short publication is a very nice piece of work. After an introduction, the publication lists the commercial microbial pesticides labeled for controlling bacterial diseases (=bactericides) and fungal diseases (=fungicides). The publication also lists the diseases each product is labeled for, and the efficacy of that product based on independent research.

Because microbial pesticides are selective for certain target diseases, growers who are knowledgeable about crop diseases have the best chance of using them successfully. Growers need to know which diseases pose a risk to their crops, so that they can select a product that will work.

Although the active ingredients of microbial pesticides pose a low risk to the environment, these products are often less effective at controlling diseases than modern chemical pesticides. This is not an indictment against these products, but simply an attempt to assure that expectations for efficacy of these products are realistic.

Information from the June 23, 2008 edition of the Kentucky Pest News from the University of Kentucky College of Agriculture.

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