Products based on microbial biocontrol agents (MBCAs) have gained acceptance as viable materials for disease, pest, and weed control in all cropping systems. Indeed, the number of commercial products based on MBCAs has grown appreciably over the past 10 years. As new, often similar products are introduced into the market, users can become confused as to the differences between products that may contain the same species of microorganism. End users should be aware that microbial strains or isolates of the same species can vary tremendously in their spectrum of activity and overall effectiveness.

Bringing a MBCA to the market involves considerable time, effort, and investment. Typically, hundreds of candidate microorganisms are isolated from multiple, diverse environments. Generally, these collections include numerous microorganisms that belong to the same species. Each of these is considered a separate strain (or isolate) because they differ in various aspects from one another. These differences are by and large due to environmental and biological characteristics of the habitats from which they were collected. These microorganisms are then evaluated based on their abilities to perform according to specific criteria such as efficacy and safety. In the end, only one or two are selected that are considered viable for registration and commercialization.

Differences in strains of the same species can be significant. Take the example of the well-know bacterium, E. coli. There are beneficial strains of E. coli that are commonly found in the human digestive tract. However, there are also strains of E. coli that are deadly to humans, such as those that cause food-borne illness, for example, E. coli O157:H7. Such differences are based on genetic factors that dictate each strain's physiology, biochemistry, and behavior. Similarly, strains of the same MBCA species can differ greatly in their survival, competitiveness, and modes of action. Further, they can also differ in their impact on plant pathogens or insect pests as well as their compatibility with host plants and growing systems.

BioWorks' MBCA products contain organisms that have been carefully selected and thoroughly tested for their quality and efficacy, as well as for their safety to the environment and workers. Trichoderma harzianum strain T-22, the active ingredient in RootShield®, was selected specifically for its ability to control a broad spectrum of soil-borne plant diseases under a wide range of environmental conditions and cropping systems. It can be considered the industry standard in soil-applied microbial biopesticides. Though there are registered and unregistered products being marketed that contain strains of T. harzianum and other Trichoderma species, these products must not be considered effective simply because they share the same name.

Beauveria bassiana strain GHA, the active ingredient in BotaniGard® and Mycotrol® O, has been the workhorse for microbial insect control for over 15 years. Its track record of safety, reliability, and performance is unmatched by any other registered Beauveria strains sold worldwide. As new strains come to the market, comparisons to GHA are inevitable. Beware that these new strains may not have the demonstrated effectiveness of BotaniGard and Mycotrol O.

We hope that this brief article has created awareness about the differences in biological control products that contain microorganisms. Armed with this information we hope that you can ask better questions to determine the best solutions for you. Contact a BioWorks representative to discuss your particular crops and growing system and to recommend programs with BioWorks products.