Biopesticides: Here Today, Here To Stay

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Powdery Mildew trial with Gerbra Daisy-treated

Powdery mildew trial with gerbera daisies: Treated with induced systemic resistance (ISR) biofungicide.

The most significant period of growth in the biopesticide market has occurred over the past several years.

Powdery Mildew trial with Gerbra Daisy-untreated

Untreated control.

“Pesticide resistance concerns and the industry’s desire to use less toxic pesticides when possible have contributed to the rise of biopesticides,” says Rick Yates, technical services manager at Griffin Greenhouse Supplies. “In some cases, they require multiple applications but used properly they can be very effective.”

Why then, does it seem a considerable number of us in this industry are still somewhat unfamiliar or uncertain about biopesticides?

According to the Environmental Protection Agency (EPA), biopesticides are derived from natural materials such as animals, plants, bacteria and some minerals. As biopesticides generally pose fewer risks than their chemical counterparts, less data is required to get EPA registration. Therefore, new biopesticides can be registered in less than a year, compared to a three-year average for chemical pesticides.

There are three major classifications of biopesticides regulated by the EPA:
1. microbial pesticides
2. biochemical pesticides
3. plant-incorporated protectants

The active ingredients in microbial pesticides are derived from a variety of microorganisms. They may contain the microorganisms themselves, the metabolites they produce or a combination of both. They can be natural, alive or dead and even genetically engineered. Typically, the active ingredient in a microbial pesticide is very specific for its intended target.

The mode of action of a biochemical pesticide typically affects the growth or the development of a pest, its ability to reproduce or its interactions with other pests, such as interference with mating induced by insect sex pheromones. Biochemical pesticides can also impact the growth and development process of a plant itself (such as a plant growth regulator).

The category of plant incorporated protectants are commonly known as genetically modified crops, in which the DNA of the plant has been modified using genetic engineering techniques.

Why Should You Consider Incorporating Biopesticides In Your Pest Management Program?

Biopesticides are lower risk than conventional chemical pesticides, making them a viable alternative for the growing organic marketplace. Most biopesticides have a significantly reduced Restricted Entry Interval (REI) and Pre-Harvest Interval (PHI),  which is beneficial at harvest time when the use of conventional pesticides can restrict the process.

In addition to the minimized toxicity, biopesticides also effectively use lower rates and decompose more quickly than conventional pesticides, creating less impact on the environment, animals and humans. Biopesticides typically affect only their intended target and can be used with beneficial insects.

Furthermore, to offset pest resistance, it is important to use multiple modes of action.

“Any time a grower can add a unique mode of action to their program to fight against pathogens, disease or insects, it’s a good thing,” says Dr. Bielinski M. Santos, previously with the University of Florida, now a product development manager for Marrone Bio Innovations. “Biopesticides offer an effective yet environmentally friendly alternative to the grower.”

Modes Of Action

There are several different modes of action in biopesticides, including:
• Antibiosisv — stimulates the growth of one organism that is damaging to another.
• Parasitism & Predation — the population of one pathogen increases at the expense of the other.
• Competition — occupies an area on the leaf or root surface, preventing the establishment of pests and pathogens on these spaces.
• Contact Inhibition — prohibits the growth and development of the pathogen and interferes with the physical integrity of pests and pathogens.
• Induced Resistance — internal defense system within the plant that enables it to resist attacks from pathogens or insects.

The concept of induced resistance has been around for a long time, but in the early 1990s it became recognized as a legitimate method toward plant disease management. There are two main categories of induced resistance; however, both achieve the same end result of inducing the plants’ resistance to the pest.

The first, systematic acquired resistance (SAR), occurs when a type of wound is created on a plant prompting necrosis (death of plant cells). A treatment, such as a microbe or salicylic acid, is applied to the area where the pathogen has attacked the plant and triggers a systematic immune response in the plant.

The second type is induced systemic resistance (ISR). With this mode of action, a physiological response in the plant is triggered to exploit the plant pathways that strengthen the structure of the plant to fight the pathogen. Additional benefits may include the production of glucanase enzymes that break down pathogen cell walls.

Growers maximize control of pests and disease when biopesticides are used as part of an overall integrated disease or pest management approach. Biopesticides can be used alone or in combination with other products.

Regardless of what you are growing and where you’re growing it, you can realize the benefits of biopesticides with resistance management, increased environmental safety, production flexibility and enhanced plant quality in a conventional or an organic program.

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