An introduction to biologicals in gardening

by | Aug 10, 2019 | Birds, Bees & Bugs | 2 comments

Gardening is biology, revolving around the biological processes of growth and life. For millions of years, plants have thrived and grown successfully with no human intervention.

biological gardening ladybird

Chemical pest control and plant nutrition have become the norm over the past 80 years, though, with many negative side effects recently emerging. The good news is that new natural innovations, offering a long-term holistic alternative, are now emerging – ‘biologicals’ for biological gardening.

A biological gardening approach centres around nature, embracing the synergistic relationships that occur naturally to ensure survival and sustainability. As gardeners we have been taught to view bacteria as germs, fungi as diseases, and insects and weeds as pests. However, the scientific truth is that many of these critters are beneficial, even essential, to healthy plant growth and development. When there is an excess of one pest species it is often an indication that the natural balance has been disturbed and an indication of vulnerability.

Natural biological control takes place continuously, in its own unique way, within every ecosystem. Using a garden as an example, biological pest control would include everything from birds feeding on grubs to owls catching rats, to ladybirds keeping aphids under control, or parasitic wasps laying their eggs on caterpillars. Even competitor plants such as alien invasives influence the ecosystem of a garden.

Finally, gardeners need to be aware that there are good pathogens – beneficial bacteria, fungi and viruses that feed on microbes and insects. There are also bacteria that are good for the soil, as probiotics are good for your stomach.

Biological products contain the naturally occurring enemies of crop pests and diseases, as well as organisms that facilitate improved root growth and nutrient uptake. These living organisms may be fungi, bacteria or viruses, in environmentally friendly and easy-to-use formulations, excellent for biological gardening.

Although perceived as a relatively new science, this technology dates back to the late 19th century, but has experienced a re-emergence with the decreasing faith in chemical agriculture. The process of identifying, screening, isolating, testing and mass producing microbes can take decades and in order for biological products to be sold commercially, they need to adhere to the same stringent controls as synthetic products in terms of efficacy and application.

biological gardening

Several strains of fungi and bacteria have been identified to be effective in the control and management of pests and diseases. Each has a unique mode-ofaction. For example, the fungal spores of Beauveria bassiana attach and penetrate through the ‘skin’ of whitefly, spider mite and various other insect pests when contact is made. The fungus grows and multiplies inside the insect, ultimately resulting in death. Similarly, beneficial bacteria Bacillus amyloliquefaciens colonises plant surfaces, occupying space at potential infection sites, utilising nutrient sources and making it difficult for pathogens such as powdery mildew to get established.

Biopesticides are not a ‘soft option’, but offer highly effective pest-management solutions. Due to their natural presence and relative host specificity they are safe for the environment, non-toxic to non-target organisms like bees, beneficial insects, pets and, most importantly, children. In addition, most bio-pesticides are residue free and can be applied to edible crops right up to harvest. They also act in a way that is unique when compared to their chemical counterparts. This makes them ideal for use in rotation with synthetic chemistry to prevent and manage pest resistance – a process whereby frequent use of the same chemistry results in a pest organism no longer being susceptible to its effect.

What does all this mean for biological gardening?

The goal of sustainable biological gardening is to grow healthy plants, in a healthy environment with minimal impact on the environment. Biopesticides offer natural, non-chemical alternatives. These may not be as immediate and as impactful as a synthetic pesticide, because they take a little longer to take effect, but they are just as effective as their chemical counterparts and should be the first option in your garden’s pest management program.