Killing them softly


Jo Arnell gives her expert advice on natural garden pest control...

I'm not sure I'm the right person to be telling you about garden pests, having come to gardening via a childhood spent communing with them. I kept snails in my doll's house, ants in matchboxes and earwig families in a margarine tub, and so (I'm almost ashamed to say) I've found it hard to carry out acts of mass destruction - even in the interests of plant protection. But most gardeners are driven to acts of violence when precious plants are reduced to miserable stumps, and I do sympathise, so here are some ideas that might help us all live in harmony, or at least, avoid unnecessary carnage in the garden.

A holistic approach...
A garden is an ecosystem, but it's quite an unnatural one and it's hard to get the balance right - and wherever there's imbalance there's an opportunity for a pest or disease to take hold. Unhappy plants are especially prone, becoming stressed if they are grown in the wrong conditions. Sun lovers will not want to sit in damp shade, delicate woodland plants will frazzle in an exposed, sunny site and acid loving plants will quickly become sad to the point of chlorosis in alkaline soil. Sickly plants have low resistance, so try to find out where the plant would grow naturally and match those conditions in your garden.

Overfeeding is another problem. Spring is the best time to give your plants food - but only if they need it. Too much nitrogen will lead to excessively lush leaf growth and soft, sappy leaves are easier to bite into. Don't feed plants much past the summer or you will encourage late growth that will be prone to winter frost damage, leaving them open to attack. Climate change is also enabling more pests to survive in situations where they might once have perished and new ones are regularly creeping in on foreign grown plants.

Catch them early...
Get out in the garden early in the season and keep an eye out for the first of the pests to arrive and you may be able to catch an infestation before it starts - the gardener's equivalent of a 'stitch in time' - 'a bug squished in the hand is better than thousands in your bushes'?? And catching them early in their life cycle will help - before they hatch and fly off to lay multitudes of eggs.

Encourage beneficial predators: set up bee/ladybird/lacewing homes and hedgehog houses, make log piles for beneficial bugs and beetles to overwinter in. Plant a nectar border to encourage hoverflies and other pollinating insects and grow plants for their seed heads to attract the birds. All birds feed insects to their young in spring and although birds will also eat your seeds, their bug catching role in spring is very useful.

Know your enemy...
Some of us are driven to thoughts of murder by the very look of an insect - but beauty is in the eye of the beholder; not all the ugly bugs are bad and many of the bad bugs have their uses. Even wasps do a good job, hunting down caterpillars and grubs.

Large pests like rabbits and deer can be a big problem, as they will decimate plants within a short space of time. Fencing is the best option - it needs to be dug into the ground at an angle to prevent burrowing, and if deer are the problem, high enough to stop a deer jumping over. There are lists of 'rabbit proof' plants available (look online), but the rabbits haven't always read these lists. In general it's the tasty new growth and young plants that they're attracted to.

In the veg patch...
Good growing conditions, resistant varieties and regular crop rotation will help prevent a build up of pests and diseases, as will regular checks on the underside of leaves for eggs and caterpillars. Netting crops at vulnerable stages will deter many - depending on the gauge of net. Fine netting will prevent flea beetle and small flies (white fly and carrot fly), the next size up will protect crops from Cabbage White butterflies and bird netting will deter pesky pigeons (make sure it's pegged down well and that wildlife can't get tangled in it).

Companion planting is an attractive way to deter pests and works by confusing the insect (they're easily confused) by disguising the smell of the crop. The most well known of these is planting carrots among onions, so that the scent of the onion masks that of the carrots and carrot flies, which can apparently smell a carrot being lifted from two miles away, won't be able to sniff them out through the onion barrier (carrot flies are also unable to fly above two feet in height, so growing carrots in raised beds or containers will confound them completely). Nasturtiums are grown among vegetables as a 'trap crop' - the theory being that Cabbage White butterflies and blackfly will be drawn to the brightly coloured nasturtiums before they find the cabbages. I'm not so convinced by this one, but a veg patch full of rambling nasturtiums is very decorative. Marigolds (French, not African) attract hoverflies and deter aphids. They are also said to repel whitefly if planted near tomatoes or in the greenhouse. I grow a tall variety called 'Mr Stripey', and I'm hoping that a new variety, Tagetes 'Tomato Growing Secret' by Thompson and Morgan wasn't given its name for nothing.

5 fiendish foes
(& how to finish them off)

Slugs and snails...
In wet years the 'most hated pest' award invariably goes to slugs and snails, but there are other contenders that come and go, usually dependant on how cold the winter is. There are endless gruesome solutions for controlling slugs and snails, but understanding a little about when they're likely to be at their most active will help. They first appear at the beginning of the season when all the fresh, succulent new growth emerges and the conditions are damp. As the weather warms up you'll find them in the cool of the early morning and at dusk and on rainy days. They don't like travelling over gritty, spiky, oily or dry surfaces and copper will give them an electric shock, so there are lots of barrier methods, and they are drawn to the smell of fermenting fruit which is why the 'slug pubs' work so well.

Vine weevil...
This is a serious pest in containers and evergreen shrubs are especially prone. The adults make notches in leaves, but the larvae do the most damage by eating the roots. You may not know they're there - until the plant suddenly dies. Check containers on purchase. A biological control is available, but only use in the warmer months, as it is temperature sensitive.

Caterpillars...
Look regularly on the undersides of leaves for caterpillars and for eggs, which are often laid in clutches and pick them off by hand. The worst culprits are the Cabbage White butterfly caterpillars, which are either bright green (Small Cabbage White), or black and white checked (Large Cabbage White). Look out for the Mullein Moth caterpillars, which are black and yellow and will attack verbascums and Gooseberry Saw Fly larvae, which will strip a Gooseberry plant, a berberis bush (same family as gooseberry) almost overnight.

Aphids (greenfly & blackfly)...
...are sap suckers (too kind a name for them) that start building up in numbers when the weather warms up in late spring. They can quickly cause large infestations because (here's a disturbing thought) they're born pregnant, so don't even have to pause to find a mate - they just keep eating and popping out babies as they go. Spraying aphids with washing up liquid was once thought to be an environmentally friendly way of eradicating them, but it's as poisonous as a pesticide and will kill all the good bugs too. A jet of water will wash them off and if you're not squeamish, just rub them off with your fingers. Aphids also make tasty snacks for baby blue tits.

Lily beetles...
...look so pretty with their gleaming orange backs and smart black undersides, but they're one of the worst of the recent pests that have spread across from mainland Europe. Their larvae have a nasty habit of hiding in their own excreta while relentlessly munching their way through the lovely lilies. The grown-ups have developed an annoying survival technique: dropping to the ground upside-down (so the black underside is uppermost and hard to spot in the soil) when you try to catch them. So out-wit them by holding one hand under the leaf they're on and then, if you don't catch them with the other hand, they'll drop into your palm. Not so pretty now are we?

Contact Jo for gardening advice and consultations on 01233 861186 email jo@hornbrookmanor.co.uk or visit www.hornbrookmanor.co.uk