Organic Gardening: Pest Control

We have only been using inorganic pesticides for the last 4 decades, and the first one DDT, was only discovered in 1948 by Paul Muller a Swiss chemist. Now you might remember what a miracle and then fiasco DDT was and still is. To put this in perspective modern man has been cultivating crops since 8000 BC. That's 9,955 years we have been successfully farming without the benefit of Mr. Heller's discovery and his resultant family of pesticides.

Garden soil can be reduced to a sterile root holder by using pesticides. If you use any pesticides at all, you effectively begin to wipe out the life in the soil and eventually, the soil merely becomes a place to anchor roots. In this type of garden copious fertiliser becomes a necessity because there are no nutrients in or being generated by the soil.

The general rule of organic gardening is to try and emulate a natural healthy system. Organic pest control can be accomplished in a number of ways, I am going to focus on; biomass, diversity, and laziness.

Key to a healthy garden system is soil biomass, or vegetation in various states of decomposition within the soil. I have seen soil in the Namibian desert turned from beach sand to thick fertile soils by simply increasing the biomass of the soil. With increased biomass comes a corresponding rise in soil life, resulting in a stable balance between pest and predator underneath the ground. This can be achieved by; composting the soil; letting the roots and bottom leaves of your garden plants decompose in situ; consistent mulching or sheet mulching of the garden surface.

A note on the structure of soil here; in undisturbed soils a very delicate structure is formed that allows for the intricacy of life in the soil e.g. miniscule gas pockets, water filtrations, mineral diffusion, bacterium, insects, worms etc. When you step on soil or compact the soil in any way you effectively crush that structure, this then inhibits prolific life in the soil until that structure is reformed. So basically if you can at all avoid it, do not compact your gardens soil, this can be attained by; narrow defined pathways; garden beds that you can reach in the middle comfortably from either side; avoid unnecessary tilling of the soil, especially if it is wet or raining; weed carefully; etc.

Diversity also has a whole host of advantages and one of them is the encouragement of predator insects, spiders and birds. You should see a steady increase in amount and variety of all three as your diversity increases, it is directly proportional. Insect life, disease and moulds love single species garden beds, its like finding an entire suburb of free restaurants, all you can eat and not far to travel. Insects also like to travel in straight lines to their next meal, and disease/moulds spread from plant zero in a circle outwards. If you plant with as much diversity as possible you make it a lot harder for insects to find their next meal. The same goes for species specific diseases and moulds, if it is hard for them to spread the less damage they can do, before you spot them. In a healthy organic garden if you do get an influx of damaging insects then you will also get an increase in their predators.

Another is a whole topic unto itself and should be mentioned in connection to diversity and pest control, this is Companion Planting. An age old tradition of planting certain plants with other plants to aid, bolster or protect them. A popular one is Mexican Marigolds (Tagetes sp.) which is an aromatic plant, above and below ground and can deter quite a few pests e.g. eelworm and cabbage white butterfly, but also attract the hover fly which eats aphids and other soft bodied insects. Inter-planting to attain diversity with various herbs, ornamentals, shrubs, etc. is a great way to do this and it makes your garden look great too. Vetiver grass (Chrysopogon zizanioides) is another useful plant against rats, snails, snakes and soil invasions. It is a dense quick tall growing grass, so watch it, but truly has a foul smelling root but thankfully only smells when they are exposed or dug up. With its 1.5 m height it can also serve as a good wind breaker, creating a tranquil enclosed ecology in windy areas.

To me laziness is the mother of invention, and in this case it's about engendering healthy natural systems in your garden, and nature will eat that bug for you. Whilst this might mean losing maybe 10% of any one crop, in the long run it really becomes an affordable loss for a greater overall gain. Think of it like tithe to nature for utilising her bounty. Laziness is also about ambling around your garden and really looking at what is going on, I always say that 80% of Organic Gardening is Observation. If you really observe and think in advance of actions you will; considerably reduce inefficient labours; catch problems before or when they start; see new ways to improve your garden.

I have avoided listing organic pesticides of which there are many, to emphasise that the goal of any gardener should be to watch, learn and act on what your garden is telling you. Organic pesticides are really the last resort, and if used should result in some deep thought as to how and why this infestation occurred in the first place, to prevent it happening again.

"I site the latin names so you might research these plants further, to ascertain what your local name for them is and what they look like"-IWH

In this series: ∙ Weed Control ∙ Compost ∙ Pest Control ∙ Companion Planting ∙ System Design ∙ Crop Rotation ∙