I worked in a retail nursery for years; I have the silhouette of customers carrying plastic bags of mouldy leaves burnt on my retina.
Inevitably the customer would present a nondescript pox-ridden leaf and demand a definitive diagnosis like "Delphinium Droop" and depart with an aerosol can proclaiming "for the treatment of Delphinium Droop" with which they could annihilate their foe. It's how many go to the doctor – they have bronchitis and want an antibiotic, not an analysis of their smoking habit.
There are military as well as medical overtones in how we talk about pests and diseases; terms like foe, battle, war and victory are hard to avoid. The military model is embedded in the agrochemical industry; remember Monsanto produced Agent Orange.
Sometimes in our desire to control our gardens we lose sight of why we are gardening. For most it's to produce healthy food, connect with nature and gain a sense of serenity. How can we do this if we see our gardens as battlegrounds? They should be as Michael Pollan extols; "a place where we can meet nature halfway."
Our gardens are part of a wider ecosystem and we are deluding ourselves that we can totally control our garden with weaponry or concoctions. A good gardener is more choreographer than commander.
Our actions seldom have specific results. Spraying "Delphinium Droop Destroyer" will affect more than the "droop." As annoying as pests can be it is more helpful to understand them than to demonise them.
Eradication of a pest or disease would inevitably come at economic as well as environmental cost; an arms race with no clear winners. Before we look at dealing with a perceived pest we need to look at acceptable levels.
This will vary from crop to crop and plant to plant. Salad vegetables are practically useless if too pock-marked or bronzed. However we may tolerate the same level of damage on an ornamental shrub at the back of a border. Don't stress over every mark and blemish; learn to manage a pest population, not eradicate it.
The basis of good pest management is observation. When does the problem happen? Can I see and describe the suspected culprit? What plants are affected? In what season, time of day or type of weather? Is the soil wet or dry? Is the plant in shade or sun?
This kind of observational information is invaluable, especially when seeking expert advice. Also, the more you do this, the more you will become the expert, solving your own problems.
Most garden problems that are blamed on beetles, caterpillars and fungi have their root cause in poor plant health and plant selection. Before heading for the aerosol, check if plants are receiving adequate nutrition remembering that over supply, particularly of nitrogen, can be as hazardous as starvation.
Have you been rotating your vegetable crops? Is the plant in the right place? A rose in poorly ventilated shade will always be susceptible to black spot and aphids. This is a garden design problem not a pest problem.
One of the fundamental ways of preventing pests and diseases in the garden is hygiene. At the most basic, keep your tools clean. Soil-borne fungi like phytophthora devastate gardens and natural bush; they can travel on a dirty spade, even muddy boots.
Clean shovels with diluted bleach after digging out a dead or diseased plant. When you are pruning susceptible plants, disinfect your tools when moving between plants to minimise the potential spread of viruses, bacteria and fungi.
Remove and destroy diseased plants and avoid using them in compost unless you are totally confident in reaching consistently high temperatures in your heap.
In our Kitchen Garden we can't run the risk of building a population of the various tomato viruses, so, when we remove the bulk of spent plants post-harvest, they are not placed into the compost.
Clean up rotting windfall. Keeping areas around high value or susceptible plants tidy can prevent pests getting a foothold.
We had a bit of a snail problem in our Herb Garden. After setting numerous, beery snail traps that dramatically reduced the problem, we only achieved final success when we cut back and tidied the surrounding rosemary and lavender – removing snails and their hidey-holes.
I must confess I really don't like squishing snails, but luckily at Heronswood we abdicate the responsibility of snailicide to our ducks. They devour them ecstatically. I prefer ecstatic ducks over chemicals any day.
Exclusion is a particularly effective organic method of plant protection. Just as you protect your home with a lock rather than shooting potential thieves; instead of doing battle with what is dining on your plants, shut them out.
White garden netting is brilliant for keeping birds out of fruit trees and berries – being white and thick they can see it and are less likely to become entangled. Again the focus is to protect our crop, not really inflict damage on our competitors. Likewise, fine woven vegetable net strung over a frame allows us to grow brassicas when cabbage moths are active without having to spray.
Fruit cages are the ultimate exclusion method. They can be found in old country gardens where whole orchards and veggie plots are enclosed in mesh to protect them from the wildlife. In possum prone suburbs a fruit cage may be only way to get a crop.
Copper sprays and tapes create effective non-toxic slug and snail barriers for precious seedlings. In our parterre we uses a motion-activated, ultrasonic noise and light show called Animal Away to deter possums and birds from entering. It seems very effective; it can even deter keen eared small children!
Why go to the effort of killing pest insects when there are so many creatures that will do the work for you?
All you need to do is provide them with suitable board and lodgings and luckily this can come in the form of ornamental flowers. Predator wasps, ladybirds, lacewings and other beneficial insects rely on pollen and nectar to provide the energy to reproduce and seek out prey.
Don't simply grow just any flowers, beneficial insects are particularly attracted to flowers from the Apiaceae (carrot/parsley) family, Asteraceae (daisy) family or the Lamiaceae (mint/sage) family. Flowers for beneficials include Bronze Fennel, Queen Anne's Lace, Borage, Sweet Alyssum and Anise Hyssop.
Think of sowing seasonal annual flowers with each vegetable sowing or sow Diggers Beneficial Insect Collection for year-round coverage. This is yet another reason to blur the line between your production and ornamental garden. Come-on you no-frills veggie growers, treat yourself to some flowers! You are not "going soft", you're killing pests in the nicest possible way. Having encouraged you to look at your plant selection, maintenance regime and other holistic approaches there are times when you do need to take the direct approach. If particularly valuable or susceptible plants are under attack, the gloves are off!
When we have to go on the direct offensive against a pest it is best to be as targeted as possible, think drone strike rather than carpet bombing. Just because a treatment is organic does not mean we shouldn't apply it with the same care and precision as more noxious chemicals.
Pyrethrum is a brilliant non-selective organic insecticide; you can even grow your own. However, its effectiveness is why you should be very selective in its use. If you have Harlequin Beetles on your hollyhocks, just spray the Harlequin Beetles, not the whole garden bed; you need to limit any friendly fire on your beneficial insects.
Alternatively Diatomaceous Earth, actually fossilised algae, is very effective and specific in killing beetles through dehydration (it also controls slugs), yet remains inert in the soil. Controlling harmful fungi in the garden is another example of when timely offensive action is needed. With humid weather, mildew and black spot can proliferate and when dealing with stone fruit, leaf curl is a perennial issue. Organic fungicides such Eco-fungicide and copper based Kocide give effective and timely control.
Traps are another way of targeting pests. Snail traps and codling moth lures are brilliant ways of controlling populations. We can even bring in hired mercenaries, beneficial organisms bought in for specific problems. Often mistaken for a chemical, Dipel is actually a beneficial bacterium effective at killing moth and butterfly caterpillars that can ruin our leafy vegetables.
There are numerous companies that sell beneficial bugs targeted for specific pests. These can be very useful especially for spider mites that are conventionally controlled with powerful chemicals.
There are great resources on the internet. Diggers website and encyclopedic texts like "What pest or disease is that" can be used to analyse specific problems and cures. What I would encourage gardeners to do is to think a bit more laterally and holistically before they reduce their garden problems to specific symptoms and cures.
As you become a good gardener, through good practice you never need be the pest and disease expert. As Michael Pollan observes it is when a gardener "respects and nurtures the wilderness of his soil and his plants that his garden seems to flourish most."