Homemade organic sprays to kill aphids on garlic

Harvest time is approaching for my first ever commercial crop: 200 square metres of garlic. And horror of horrors, the aphids have moved in.

 Fortunately, I spotted them when they had only colonised a small corner of the plot. But they had to be stopped, and quickly.

 You’ve got to be careful with sprays, even organic ones. Non-pest-specific sprays such as these will hurt good insects as well as bad so they should only be used as a last resort (aphids on my garlic is an emergency; they spread garlic virus as well as weakening plants).

 It’s also important to avoid using oil on days when the temperature will exceed 30 degrees, and to spray in the cool of early morning or late afternoon. This prevents the oil scorching the leaves, and means you’re less likely to harm beneficial insects such as bees, because they won’t be as active.

 The above pic shows the aphids getting doused. You have to make sure the sprays drip right down into the base of the leaves, where the cheeky so-and-so’s like to hang out. While I am, on the whole, a gentle, peace-loving kind of guy, I can’t tell you how good it was to see those suckers suffocate.

 I’ll be down there checking my plants and doing follow-up sprays as necessary in the days and weeks to come.

 The following spray recipes appear in two important upcoming publications: Penny Woodward’s new edition of Pest-Repellent Plants, coming out next year, and the Organic Gardener Essential Guide: Herbs & Spices, which hits newsagents’ shelves on November 9.

 Soap spray

Traditionally used against: aphids, beetles, harlequin and shield bugs, caterpillars, mites, mealy bugs, scale and whitefly.

Half-fill a bucket with warm water and vigorously rub your hands with a cake of vegetable-oil-based soap until the water is milky. Or use 1 tablespoon of natural soap flakes, or 1 teaspoon of eco-friendly laundry or dishwashing detergent. Don’t use more or you may damage plants.

 White oil spray

Traditionally used against: aphids, small caterpillars, leaf miners, mealy bugs, mites and scale.

Pour 500ml vegetable oil and 100ml liquid soap into a large jar or bottle with a secure lid. Shake vigorously until blended. Label and store in a cool spot. To use, shake well and add 1 tablespoon of concentrate to 1L of water. 

 Photo: SIMON WEBSTER