Biological Bug Blasting

By Pippa Greenwood

Now that warmer weather has arrived, plants in the protected environment of a greenhouse or conservatory are likely to suffer attacks from pests and diseases. Why not tackle some of the more common pests using biological controls? They work well provided you have not used chemicals recently and don’t intend to introduce them. Biological controls may sound high-tech, but you are simply introducing tiny creatures in to control the pests, with no need for chemicals and therefore no chemical residues left on edible crops either. They’re safe for humans, pets and wildlife too! There are great controls for many outdoor pests, including slugs (Nemaslug), chafer grubs and leatherjackets, and one control with a wide range of vegetable-crop pest controllers in it. There is a nematode control for vine weevils that can be watered on to the compost of edible or ornamental plants. Best used in spring and autumn when there are higher levels of the grubs, it is easily applied with a watering can and is not too expensive. In greenhouses, plant-wrecking red spider mite and glasshouse whitefly numbers soon build up as the weather gets warmer. Whitefly also have a nasty habit of producing a very sticky excreta called honeydew and this causes a sugary layer to appear on the plants, often followed by black mould growth known as sooty mould. I’ve used a tiny parasitic wasp, Encarsia, with great results. This extremely small wasp lays her eggs in the young stage of the whitefly (often called the whitefly scale), killing it in the process, and then new Encarsia wasps hatch out of the parasitised whitefly scales. Provided there are some whitefly in the greenhouse, and as long as temperatures average 10C (50F), it works a treat. Red spider mites (which cause minute but densely packed flecking on the plant foliage, often followed by browning and dieback) are tiny and difficult to spot, and you may only notice the devastation they cause. These pests thrive in the warmer drier conditions likely to prevail a little later in the year, but they can be controlled biologically too with a predatory mite known as Phytoseiulus. This tiny mite has a voracious appetite for all the life stages of the red spider mite and can be introduced as long as average temperatures are about 16C (61F). You can also get biological controls for other common greenhouse and conservatory pests, such as aphids (greenfly and blackfly), scale insects and mealy bugs. It really is a good way to keep pests down and provided you follow the instructions this truly environmentfriendly (and gardener-friendly too!) method takes some beating, so why not turn over a new leaf this year and let biological controls do the work for you? All the controls mentioned above are available from most biological control suppliers.

At www.pippagreenwood.com you’ll find a range of pet-and-wildlife-friendly bio-controls, Speedweeders, the fantastic SpeedHoe, signed books and more. To advertise in The Villager and Town Life please call 01767 261122