Whether you’re a grower, packer, processor, or retailer, you have experienced the dramatic shift in consumer preference for sustainable practices in the production process. Not only has this trend driven changes in the U.S., it’s also dramatically impacted your ability to develop and service overseas markets. In many of these countries, chemical residue limitations and sustainability requirements have driven a larger emphasis on developing effective, economical, and sustainable practices that produce a quality crop without sacrificing profit.
It’s no secret that the overdependence on synthetic chemical pesticides and the decades of uninhibited use of such chemistries has necessitated a change in practices. Those changes have mainly been focused on degraded soils and groundwater pollution resulting in nutritionally imbalanced and unproductive ground.
Biopesticides are becoming a critical tool in the increasingly limited tool box for conventional and organic growers alike. These materials provide a variety of implementation opportunities for your standard integrated pest management (IPM) program. Biopesticides are generally put into three primary categories:
Biochemicals are naturally occurring substances that control pests by non-toxic mechanisms, including:
■ Broad-spectrum contact bactericides/fungicides (peracetic acid, or PAA; fatty acids; potassium bicarbonate; copper; sulfur and/or lime-sulfur)
■ Plant extracts (neem oil/azadirachtin, giant knotweed, pyrethrum plant)
■ Insect sex pheromones (monitoring, trapping, and mating disruption)
Microbial pesticides, or biologicals, consist of a microorganism as the primary active ingredient; many target specific pests and, thus, are less broad-spectrum.
■ Bacillus spp.
■ Pseudomonas spp.
■ Trichoderma spp.
■ Gliocladium catenulatum spp.
■ Beauveria bassiana
Plant-Incorporated-Protectants (PIPs) are pesticidal substances that plants produce from genetic material that has been added to the plant. The Bt gene from Bacillus thuringensis (Bt cotton and Bt corn) is an example.
Biochemicals and Biologicals Together
The crop protection industry and the researcher community as a whole have been rapidly developing supporting research on these relatively new technologies and how they can be incorporated into an IPM program. One of the lingering myths that researchers, consultants, and manufacturers are working to address is the perception that two of these biopesticide categories, biochemicals and biologicals, are difficult to use together in an effective IPM program. Biopesticide suppliers are working with university researchers, Extension agents, and independent crop advisors to show how these two tools can be extremely effective in combination, and that they have proven synergistic properties that provide increased efficacy and performance when used as rotational partners in a grower’s pest management program.
Biochemicals and biologicals provide a host of advantages in both curative and preventative programs. Biochemicals tend to be broad-spectrum, non-target-specific chemistries that are ideal for eradicating established fungal pathogens and their spores, as well as established bacterial diseases and their inoculum, which is critical when trying to stop the spread of pathogens through a field. Biochemicals, such as peracetic acid (PAA) and potassium bicarbonate, are effective at cleaning the foliar surface and treated area, providing immediate knock down of pathogens and their dormant spores or inoculum.
The unique properties of biochemicals make them a critical partner when using biological tools to aid in preventive control of foliar and soil pathogens. Biochemicals must be applied prior to the use of a biological product, with the biochemical reducing the current high levels of fungal spores and/or bacterial inoculum. With most biochemicals providing kill immediately on contact and then converting into inert properties, biological tools can be quickly applied following the application of the biochemical. It’s these unique principles that provide the synergistic properties between the biochemicals and biologicals:
■ The biochemical provides curative properties of established pathogens on the foliar surface. When used in soil applications, it helps reduce the populations of soil-borne pathogens.
■ Immediately following a biochemical application, growers can apply a biological product to the foliar surface or into the soil profile. Components of the biological fungicide can then rapidly populate on the treated surface without having to overcome high populations of dormant or active fungal or bacterial pathogens.
This is a major innovation in IPM. Biochemicals can play a major role in reducing the moderate to high populations of foliar and soil pathogens present in the field, providing a clean environment for the beneficial organisms used in biological products to populate around the leaf surface. Many of the biological products use beneficial strains whose primary mode of action is exclusion, meaning they populate at a rapid rate. Thus, they inhibit plant pathogens from re-establishing on the treated surface, without having to overcome or compete against existing high populations of both plant pathogens or other yeasts, molds, or fungus naturally present in the environment. This unique IPM approach has shown success in soil treatment studies, where a soil treatment such as PAA is chemigated through drip irrigation systems to eliminate soil pathogens such as Pythium, Phytophthora, and Fusarium prior to or just at planting. PAA quickly breaks down into inert components of oxygen and water and leaves no harmful by-products behind. Growers can then quickly inject beneficial organisms back into the soil profile, allowing them to colonize and populate rapidly and efficiently with competing organisms having been reduced by the biochemical application.