Organic insect and disease control
When there’s a problem in your garden you want a safe cure. Some people search for homemade remedies, but many of these are messy to make or apply and may often harm the very plant you are trying to protect. Nurseries now recognise the modern gardener’s need for safe and convenient pest and disease control products and stock a range of organic pesticides.
These products feature active ingredients such as spinosad, Bacillus thuringiensis, neem, pyrethrum, copper, sulfur, potassium, soap and horticultural oils that are just what grandma would have used, only better. Although many of these products kill pest insects or clear up disease problems, most do not harm beneficial insects such as bees, ladybirds and hover flies, and all are safe to use on edible crops as well as flowering plants.
What’s in the container?
To see which active ingredient is in a product you are buying at the garden centre, look carefully at the label. Beneath the brand name will be clearly listed (if in small writing) the name of the chemical or chemicals it contains. Even though the following active ingredients are considered safe, always follow the label instructions for application rates and frequency of application along with any precautions that must be followed. Here are some of the garden-safe ingredients you may find in organically friendly modern pesticides.
- Spinosad is an insecticide derived from a naturally occurring soil bacteria. It doesn’t harm humans but does kill many common insect pests including caterpillars, fruit fly, thrips and pear and cherry slug by affecting their nervous systems though ingestion or by contact. It is also used in some flea medications for pets.
Try: Success or Eco-Naturalure
- Bacillus thuringiensis (Bt) is also a bacteria that works as an insecticide and is one of the oldest commercially available organic insecticides. Bt targets caterpillars that turn into moths or butterflies.
- Neem is a plant extract that works as an insecticide without harming us or beneficial insects or animals. It can be used to organically control many chewing and sucking insects such as aphids, mites, caterpillars, curl grubs, lawn armyworm, fungus gnats and whitefly.
- Pyrethrum is a plant extract that’s a powerful broad-spectrum insecticide but one which has low toxicity to humans. It is used to kill aphids and other sucking insects. It has also been synthesised as pyrethrin.
Try: Amgrow Pyrethrum
- Copper is a fungicide used by generations of gardeners to control fungal diseases including rusts, leaf spot and rots in a wide range of plants. It can be applied as a winter wash to prevent diseases such as brown rot and other fungal disease of fruiting and ornamental plants. It may also be used to control fungal problems that appear through the growing season.
Try: Copper Oxychloride
- Sulfur is another naturally occurring fungicide long used in agriculture and horticulture. It is found in products such as lime sulfur and copper sulfate to control a wide range of fungal problems and is particularly useful as a preventative spray that’s applied in winter against problems such as peach leaf curl and rose black spot. Sulfur can also control some pests including mites. Take care when using sulfur as it can burn foliage especially on hot days.
Try: Manutec Wettable Sulphur or Yates Leaf Curl Spray
- Potassium is used as a fungicide to control disease problems such as rust, black spot in roses and powdery mildew. It can kill existing fungus and also prevent new outbreaks. It can be combined with oils as an all in one organic insecticide and fungicide.
- Horticultural soap is a useful insecticide used to control aphids, mites, thrips, whitefly and mealy bug. You can make your own spray by grating pure soap or using pure soap flakes but commercial preparations are available that are easy to mix up and apply without risk of harm to leaf tissue or the soil.
Try: Yates Nature's Way Insect and Mite Killer Natrasoap
- Horticultural oils (also called spray oils, eco oils or pest oils) are very fine grade oils that kill insects by smothering their breathing tubes. Oils can also deter insects from laying eggs in foliage (for example when used to protect citrus leaves from citrus leaf miner).