I am fascinated by how you can manage pest and disease problems by having the right garden guardians or ‘good guys’ present to control the pest insects or ‘bad guys’.
Happy = healthy
Growing healthy plants starts with suitable plant selection, and in most cases involves developing good soil with the addition of organic matter and nourishing your plants appropriately to keep them in optimal health. As I have said many times, happy healthy plants don’t get sick and if they do they are more likely to recover quickly. However when it comes to fruit trees and vegetables, often we are growing varieties that are not suitable or climate compatible, but we still want to grow them. By growing them out of their optimal environment they are under stress and as such more vulnerable or susceptible to pest and disease problems.
So the next level of defence in a garden is to bring in the garden guardians. While these so include birds, lizards, and bats, this page is devoted to small garden guardians – insects including ladybirds and hoverflies.
Many of these garden guardian insects such as ladybirds, hoverflies and lacewings are nectar feeders, while their juvenile larval forms are the ravenous carnivores of garden beasties such as aphids and white flies. To keep these creatures happy you must have a good selection of flowering insectary plants that bloom throughout the year, especially those which produce masses of small flowers, to provide pollen and nectar. Plant long flowering annuals such as alyssum and Phacelia. Herbs such as basil, bergamot, borage, lavender, mint, oregano, rosemary and thyme are also a great source of food for these insects when they are in flower.
Daisies and umbels
Another way to be sure you have good guys is to plant two types of flowers – daisies and umbels. While a daisy looks like one flower, it is actually made up of many tiny flowers, each bearing pollen and nectar and that’s why they are magnets for pollinators. Suitable flowers with a daisy form include calendula, yarrow, chamomile, feverfew and sunflowers. Umbels are a magnet for pest controlling predators. All umbel flowers have a distinctive signature structure – short flower stalks that radiate from a central point and it is the silhouette of this form that is irresistible to the eye of predator insects. There are flat umbels like carrots, Italian flat leaf parsley, dill, fennel, coriander and angelica. There are also globe shaped umbels that are found on members of the onion family including chives and spring onions. Umbel flowers promise pollen and nectar and they are easy landing pads for smaller insects.
A surprising plant proven to attract many beneficial insects is saltbush. A number of market gardeners on the northern Adelaide Plains found that by planting these hardy natives around their crops and shade houses, their pest problems were dramatically reduced. See http://www.abc.net.au/gardening/stories/s3606762.htm
Water is also another requirement of many garden guardians.
Organic gardening practices are essential for all gardeners wanting to encourage these garden guardians to make gardening easier for you. Stop using toxic garden sprays and synthetic fertilisers and only use products that are environmentally friendly. Even some natural sprays such as pyrethrum can be toxic to the good guys in your garden as they are non specific and kill both the bad bugs and the good bugs.
Finally, allow some sacrificial plants for the insect pests to over-winter on, as without some aphids in your garden, what will the ladybirds eat? Leaving the odd thistle or two will not harm anything as long as it is removed before it seeds.