Prevention is the best way to keep garden diseases and unwanted bugs to a minimum.
Beer trap for snails, photo Steven McNicholl/NZH
There’s an early invasion in the garden this year. Although my Dublin Bay rose is not yet in bloom, the rust is already in evidence and there’s black spot splashed over the leaves. It could be my fault for growing roses in Auckland, but if that’s the argument, why are my nikau and pseudopanax also hosting rust? This year’s mild winter in the north has come at a cost, and so I expect the bugs are going to have the upper hand, having barely been knocked back. Down south, however, the late cold burst that knocked back early season crops will have dealt to those first bugs, too.
So, what to do if you don’t want to spray your garden?
I have three beautiful topiary buxus balls left over from a display I did last year. Over the winter, one began to dramatically blacken and defoliate. Winter did little to stop the decline; the black moved over the ball like a brewing storm. Despite my aversion to spray, I bought some organic copper, but I just couldn’t bring myself to use it with two small children around. The packet is still sitting in the cupboard. Instead, I decided to smother the plant with love. I lifted it into a pot and loaded it with sheep pellets and fresh potting mix. Twice weekly I’ve drizzled it with fresh worm juice and liquid seaweed, and occasionally I’ve asked it how it’s doing. And what a difference a little kindness has made. The brown and dusty corpse has done a Lazarus. Again, it is a spherical flush of spring green.
If we take the approach of managing disease in our garden in much the same way as we manage our health, prevention is better than any cure. It’s well proven that if we treat every snuffle that comes along, we reduce our body’s ability to develop its own immunity. I’m convinced this is the same with plants. We won’t end up with a pest-free garden, but we’ll have a better chance of a healthy one.
A year or two ago I planted a camellia hedge while we were at war with a posse of possums that had been making nightly raids on our garden. Not every camellia received a composting possum, but I’d swear there is at least a 15cm growth difference between those planted with a possum corpse and those without – although I can’t prove it. They’ve all received even quantities of sheep pellets and worm food, and aspect is not a consideration. Perhaps one possum per plant is just the boost the doctor ordered.
The first requirements are healthy soil and consistent water supply. I swear by bucketloads of compost, sheep pellets and liquid fertilisers, be they seaweed-, fish- or worm-based. These products carry nutrients that stimulate the soil, bringing it to life. Although slow-release fertilisers help plants grow, they do not condition the soil. Conditioning soil with good humus helps the even dispersal of nutrients and water through borders and garden beds. It will also encourage worms and other soil dwellers into the garden, which in turn help maintain a healthy foundation.
Despite many of our crops, such as potatoes and carrots, being earthbound, it’s easy to forget how much of a plant lives underground. When moving plants, gardeners should take the time to study their roots. Root systems are beautifully intricate, and studying these vein-like structures helps us understand how plants grow and why soil quality is so important. When nutrients are part of the substance of the soil, plants and other organisms can make use of them. Think of the soil as a sponge or filter that evenly divvies out the nutrients as required.
Early bursts of fertiliser lead to uneven distribution, resulting in plants being burnt. Unnecessary nutrients cause imbalance in our gardens or leach into waterways. To counter this, slow-release fertiliser was developed. This is an effective way to deliver the nutrients, but if the soil quality isn’t also considered, it is the equivalent of us living off a protein milkshake. Like us, plants need bulk and fibre as well as fuel.
Large trees and shrubs need an environment of good soil quality to encourage the roots to push through to anchor the plant in the earth while readily accessing minerals from deep within the soil.
Minerals are also an important aspect of plant health, especially those that produce food. There is not much advantage in a home-grown organic diet if it is lacking the minerals required for health. It is likely these will need to be added to soil, particularly in vegetable gardens where the soil is being worked hard. This can be done by various methods such as deep-rooting green mulch crops that fix nitrogen or bring minerals up from the soil. Enrich your soil by digging in green manure crops such as lupins and comfrey, by adding seaweed and trace elements to your composting programme or by using products that contain these things.
Once your soil is in good condition, watering becomes more important. The supply needs to be as consistent and responsive to the environment as possible. With healthy nutrition and watering, your plants are in a good position to defend themselves from disease. However, snails and caterpillars won’t stop visiting.
This is where garden hygiene becomes important. Just as we clean the cobwebs from our houses, a weekly snail sweep of our gardens will reduce numbers significantly. Tools need to be cleaned regularly and if you have used secateurs to prune back sick or diseased plants you must sterilise them before using them elsewhere in your garden. Just as we clean our own wounds, removing and burning diseased and infected foliage is as important to prevent anything spreading. Don’t put these diseased prunings or plants in your compost, though.
Garden hygiene even goes as far as washing down your plants. Soapy water is very effective at discouraging many common garden pests and even a squirt of the hose can do wonders. Keeping the garden areas tidy can ensure you limit the number of welcoming places for bugs to hide. A quick tidy up of my old plastic pots brought in close to 30 snails.
In some cases, quarantine may be required if you wish to save an ailing plant. Alternatively, swift removal for the common good may be the best option if space and energy don’t allow a sickbay in your garden. Remember, though, a beautiful garden is not just nature. It is also nurture and a little bit of worm juice goes a long way.
BEATING THE BUGS
- When controlling insects in your garden, focus your attacks on the unwanted species, as this will reduce the impact on beneficial insects.
- Smearing oil on a yellow plastic lid can be effective against smaller insects. They are attracted to the bright yellow colour, then get stuck in the oil.
- Pheromone traps are a great way to control pests such as codling moth. The trick is timing; the traps need to be put out to coincide with breeding patterns, so do some research first.
- Snails are best controlled by a nightly snail sweep. Beer traps (burying a bottle with 2cm of beer in the bottom) and a sprinkling of crushed shell around young seedlings are effective only in a localised way, making them ideal for small gardens.
- Chilli and garlic sprays are effective deterrents that won’t greatly harm general insect populations. A squirt of dishwashing detergent in the spray mix will help it stick to the leaves.
- Fungal outbreaks can be managed with a spray made of baking soda dissolved in water. Alternatively, copper spray is effective – and it’s approved by organic growers.