Monday, May 2, 2022

The World of Biorational Controls

A drawing of hands holding a glass globe with flowers all over it.

It wasn’t that many years ago that organic and natural pesticides were virtually non-existent in the retail sphere, so home gardeners, hobby farmers and the like had to make difficult decisions about the products they used. Thankfully, that’s changed greatly and nowadays we have a world of biorational controls to choose from.

There’s no hard and fast definition of biorational controls; the term covers products that have a reduced risk to living things and have little to no impact on the environment. This characterization is especially important when discussing pest control, fungicides and herbicides – all of which have an over-representation of toxic products on the market. Biopesticides (biological pesticides) and biofungicides (biological fungicides), certain minerals, botanical extracts, herbicides and soaps all fall within the biorational parameters. 


Four insects covered in a white fungus - Beauvaria bassiana at work.
Beauvaria bassiana at work
This is arguably the category that’s seen the most innovation in the last 10 years or so. There are many types of biopesticides these days, including:

• Insecticides that use entomopathogenic fungi to kill specific groups of insects, like Beauvaria bassiana which infects a wide range of insects with deadly white muscardine disease and Isaria fumosorosea Apopka Strain 97 that kills mites and soft-bodied insects.

• Insecticides that use targeted strains of bacteria to kill specific insects, like Bacillus thuringiensis israelensis (Bti) that kills mosquito larvae, and Bacillus thuringiensis kurstaki (Btk), which kills Lepidoptera caterpillars.

• Insecticides that come from plant-derived oils and their extracts like Neem Oil and
Chrysanthemum cinerarifolium daisies, the pyrethrin daisy
Pyrethrins. Neem comes from the Neem tree, a native to the Indian subcontinent; it will kill soft-bodied insects and is also useful as a deterrent or repellent. Pyrethrins come from the Chrysanthemum cinerarifolium, a daisy, and can be used to control both soft-bodied and hard-shelled insects.

Biofungicides also use a variety of beneficial microorganisms to control plant pathogens like powdery mildew and botrytis. They work in multiple ways, but generally speaking they overpower the pathogens and out-compete them for resources. The ingredients in some common biofungicides include:

An illustration of rod-shaped microbes - Bacillus subtilis
Bacillus subtilis
• Bacillus amyloliquefaciens strain D747, a naturally occurring soil bacteria

• Bacillus subtilis – a bacteria found in the soil and the gastrointestinal tract of certain animals

 Trichoderma – This is a group of soil-dwelling fungi of which certain strains have been developed for maximum efficacy in the plant world. 

Bottles full of thyme oil with thyme leaves all around.
 Inorganic compounds like potassium bicarbonate, the active ingredient in Milstop 

 Botanical oils like the Thyme Oil in Thymox Control Organic.

These are deeply researched and complex products that are, nevertheless, easy to use and readily available to any size grower. I strongly encourage you to dig deeper into these categories; there are many products than I have pointed out and there is much more information on each product page. 

A woman wearing a hat inspecting a plant in a field of crops.
Biopesticides and biofungicides are excellent choices for IPM program and because they often only affect targeted pests, using them reduces the effects to non-target organisms. These products also cut down the danger of residual pollution and eliminate the problem of pesticide/fungicide resistance. They are also cost-effective overall as they reduce the need, and thus the cost, of conventional products.


Complex rice terraces on a mountaintop in southern China.
Rice Terraces in Southern China
Mineral-based biorational controls are often products that have been around for a long time but are getting new respect as the interest in safe and natural solutions grow. For example, the use of kaolin clay for pest control dates back over 2,000 years. It works as a crop protectant and will also repel pests, cause irritation and confusion, and create an obstacle for feeding and egg-laying. The popularity of the kaolin clay product we carry, Surround WP, shows that modern consumers still see the value in this biorational mineral. Diatomaceous Earth (DE) has been used in China for 4,000 years. DE comes from the fossilized shells of microorganisms known as diatoms that has been crushed into a fine dust. It has innumerable microscopic sharp edges that cling to insects as they pass through it and mortally wound them by cutting up their exoskeletons. It will also absorb the waxy cuticle around the insect, which causes it to dehydrate and die in as little as 48 hours.
Leaves and petals spilling from a black bottles.

Botanical Extracts

Talk about a product line that has exploded in the last few decades! Using botanical oils for pest control is another case of an ancient-but-still-excellent method. Mineral biorationals  may have changed very little over millennia,  but oils have enjoyed a renaissance as newer, more target-specific and user-friendly formulas have been developed. Botanicals can now be found in pesticides, fungicides, bactericides and repellents. For more information on some of the most commonly used botanical extracts, check out my blog on the subject here. Happily, the use of botanicals is becoming main-stream; they’re easy on the environment in general and their use falls well within the principles of IPM.

A white picket fence with pink flowers in front of it and a sign that says, "Experimental Dandelion Farm. Do not disturb weeds".

We have come a long way from spraying highly-toxic herbicides like DDT all over everything. Nowadays most people understand the need to keep weed control products, not just weeds, in check.  Biorational herbicides use a wide variety of ingredients to great effect. We carry herbicides that use corn gluten meal, botanical oils, iron, barrier controls, d-limonene (citrus oil), ammonium nonanoate (BioSafe Weed & Grass Killer) and citric acid. Biorational herbicides will not produce the quick knockdown of weeds that the toxic sprays can, but they are still highly effective for the patient and conscientious consumer.

A woman holding a white plastic sprayer and aiming it at plants.


Biorational insecticidal soaps are another product line that reflect the modernization and upgrade of an old school DIY form of pest control. Insecticidal soaps these days are potassium salts of fatty acids and are used to control soft-bodied insects and some path pathogens. One of our customer-favorite soaps is M-Pede, which, in addition to its insecticidal properties, is labeled as a curative control for powdery mildew.

Two children running happily through a garden.
As far as our pest control products go here at ARBICO, we have very few that cannot be classified as  biorational (traps come to mind). There are still some hard-to-kill pests that we struggle to find biorational controls for, but we are committed to finding as many as we possibly can and presenting them to you as soon as we do.

Submitted by Pam

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