Like death and taxes, pesticide resistance is inevitable. Sooner or later, pests will develop insensitivity or resistance to chemical pesticides. The aim of pest resistance management is to postpone or delay resistance if possible. Biological seed treatments are a valuable and effective tool in the ongoing resistance battle.
Pest resistance is not to be taken lightly. A limited number of chemistries exist to control pests, with even fewer new chemistries in the development pipeline. Older chemistries already carry the brunt of the load. For some of the most widely used chemistries, the base rates labeled have been increased to maintain efficacy. If we let pests develop resistance to these, there may be nothing available to take their place.
Because chemical and biological controls work differently, they can be used together to improve their effectiveness. Regardless of soil temperature, the hard chemistries begin working immediately, whereas biologicals prefer warmer soil temperatures. Just as the hard chemistries begin to wane 30-45 days after planting, the biological control mechanism is becoming more active on the root system. The combination of early chemical activity and later biological activity keeps the seed cloaked in protection, extending the span of protection beyond what either product can do alone.
In other applications, biologicals complement the range of coverage provided by chemical controls. Adding multiple chemistries with similar modes of action provides redundant control of the same pests while leaving others unscathed. Adding biologicals introduces different modes of action to the mix that reach different pests. We are just now understanding how one biological strain can work differently in different soil environments. A biological treatment that is extremely effective in one area may provide only marginal benefits elsewhere.
No single product, whether chemical or biological, is capable by itself of being the silver bullet to control the entire spectrum of early-season seed and seedling pests. Biologicals provide alternative and complementary methods of pest control and resistance management. It takes careful attention and diligent analysis to select the most effective combination of chemistries and biologicals. This is the effort needed if we are to maintain effective, long-term pest management.