Les Davies MBEOutdoors

Let the good bugs attack the bad bugs

As more and more pesticides are removed from the shelves in garden centres, gardeners will need, quite rightly, to turn to more environmentally friendly forms of pest control. The horticultural industry has been turning to a much greater use of With MARY PAYNE MBE biological control of some pests for many years and adopting Integrated Pest Management (IPM) using a combination of safe pesticides and biological control to keep problems at bay. sharp-eyed visitors to many garden centres in spring may spot small packages dotted around the plants, especially in the bedding plant display areas. These are introducing keep the pots really moist so that the nematodes can move predators to gobble up greenfly or other pests you would not around and search out the grubs. wish to take home. You are getting added value as you may A similar product can be used against the larvae of fungus well be taking home a useful predator! flies. These are tiny flies that often hover around trays of

Biological control has many advantages over chemical seedlings or pots especially if they are rather too wet. pesticides. Your plants are not damaged and the good bugs Alternatively, easing back on the watering will help no end. are host specific so will not become a problem to other For owners of greenhouses, growing perhaps tomatoes and creatures. They are ideal for use on food crops and the bad cucumbers, the use of parasites and predators can be extremely bugs do not develop a resistance to the good bugs, as can successful. Glasshouse red spider mite on cucumbers and other happen with pesticides. plants can be a real problem, but two predatory mites are

In recent years, the range of pests controllable by biological excellent at controlling them. means has widened considerably. Basically, it involves the Amblyseius is ideal for spring use when temperatures are introduction of either a parasitic insect that lays its eggs in lower, whilst Phytoseiulus is ideal for high summer. Either the pest leading to death, or predators which wander around should be introduced as soon as there are signs of an infestation. gobbling up your pest. A third approach involves transmitting I regularly use these good bugs with great success. a fatal bacterial disease to the pest via a suitable vector. All Tomatoes regularly suffer from glasshouse whitefly. Tiny sounds a bit like science fiction, but it really works. white mothlike flies take off in clouds when the foliage is

Many different products are now available on the amateur disturbed. A tiny parasitic wasp, Encarsia, is introduced and lays market and can be very effective if the conditions are right. its eggs in the immature scales of the whitefly. The scales turn so, it is vital to read the instructions and important to realise black when parasitised giving an excellent indication of the good that these beneficial creatures are alive and have a limited deed that the bug is doing. shelf-life. Each one has its own conditions under which it Greenfly and other aphids have several natural predators works most effectively and this usually involves a limited including wasps, lacewings, earwigs, ladybirds and of course temperature range. Between April and september is the ideal blue tits. Outdoors in our gardens another native tiny parasitic time for most when used outdoors. wasp is at work laying its eggs in the bodies of aphids. The

The pests that plague every garden are slugs and snails. greenfly body changes to a buff colour as the wasp larvae slug pellets based on metaldehyde have now been withdrawn develops and the new adult emerges leaving an empty shell. If leaving us the ones based on ferric phosphate, but you may you find these empty bodies then leave well alone. These “good care to try the biological approach. This uses an eelworm, or guys” can be introduced to greenhouses if necessary. nematode, a microscopic worm-like creature, which transfers Another approach to biological control is to use pheromone a fatal bacterial disease to the slugs. traps to lure the male pest to a sticky end. This method uses the

These good bugs are applied as a drench to the soil. They scent of the female sex hormone for each different species to have a limited effect on snails which tend to live above trap the male on a sticky platform so that he cannot mate with ground, while the nematode lives in the soil, so only slugs females. These traps are available for an increasingly wide range that go underground by day are affected by it. Different of pests including codling moth (the grub inside apples), plum species of nematodes are used for the control of moth (grub inside plum), tortrix moth (leaves folded with leatherjackets and chafer grubs in lawns in a similar fashion. webbing), pea moth (small grub in pods) and box caterpillar

It is important to keep the lawn or compost moist during (foliage devastation). the treatment period as the nematodes need water to get They are unlikely to give total control, but can reduce about. These are best applied in the late summer/autumn infestations to a more acceptable level and it is possible to see when the soil temperatures are still warmish. the level of infestation around by the number of adults stuck to

The second most hated pest in the garden is vine weevil. the trap. The weevil larvae have a devastating effect on plants, Biological control is going on all around us in the natural especially those in pots, when the small creamy coloured world and is increasingly being encouraged in agriculture and grubs eat the roots. several different species of nematodes horticulture. All the “good bugs” are available online or can be used as a drench to the soil and pots, ideally during increasingly at many garden centres. Give it a go and help save the late summer to control the larvae, but again it is vital to our planet.