Keeping Your Garden Safe From Pests And Diseases

It might be convenient to contain this subject in various sections, starting with the lawn.

May and June are the months to attack the many weeds which appear in the grass – that is, provided conditions are moist. Most of them – cat’s-ear, crowfoot, plantain, ribwort and the like – can be controlled by hormone weedkillers or lawn sand.

Other enemies, like moss (usually the result of poor drainage, too much shade or close mowing), over-acid soil, lichen and algae can be killed by applications of lawn sand. Worms, the gardener’s friends in many respects, are a nuisance on lawns, making unsightly casts. Their tunnels, too, tend to make the surface soft. There are chemical powders which kill them but it’s better, if possible, simply to discourage them, so avoid excessive use of fertilisers, and don’t leave cuttings on the lawn.

Toadstools, puffballs and fairy rings can be eradicated by a solution of two ounces of Epsom salts in a gallon of water applied to each square yard of the affected area. Small patches of brown, dead grass indicate leatherjackets – a real pest – and you can buy chemical powders which will sort them out. Other causes of grass discolouration can be buried debris, drought, over-compaction (which means your lawn needs spiking with a garden fork) and lady dogs!

Now to the vegetable garden – and how depressing it can be to see your harvest under attack. The answer is: be ever watchful. From April onwards make a weekly inspection and use the appropriate spray the moment the enemy is sighted. Generally speaking, here is what to look for: leaves turning grey or brown with a fine web and minute insects means red spider, usually on beans or tomatoes. On peas, white, powdery mould means pea mildew. Leaf edges notched on peas and beans means weevil, and distorted pods mean thrips are at work. Greenfly and blackfly appear on tips of plants. Holes in cabbage leaves mean caterpillars, and chewed stems at ground level are a sign that the cutworm has been busy.

Young carrot, celery and parsnip plants wilt and die under attack from the carrot fly; so too do seedlings of turnips, cabbages and other brassicas attacked by the flea beetle. Underground the war goes on from wireworms, carrot, onion and cabbage root fly, potato blight and wart disease, club root and scab. But there’s a formidable array of weapons to hand, enabling you to fight back and destroy.

The leaf-curling plum aphis and the currant leaf blister aphis spend the winter, as eggs,~in nooks and crannies in the bark of trees and should be sprayed then, before they hatch. Other pests, too, should be attacked in winter, before they get a chance to do their dirty work. The apple blossom weevil, sawfly, capsid bug, sucker and codling moth are examples. The big bud mite can play havoc with currants. Affected buds are easily spotted as they swell to twice their normal size and subsequently die. All you can do with these is pick them off and burn them – but you can, of course, defend against this horror with a spray. Small blue spots on raspberry canes, leaves which turn mottled yellow, and raspberry beetles, which appear as grubs inside the fruit, must all come under attack.

Gooseberries suffer from sawfly, which devour their leaves, and mildew, which appears as a white coating on leaves, stem and fruit. Strawberries are prone to mildew and grey mould, which are easily recognised, as is the work of hungry slugs, snails and beetles. Peach leaf-curl is unmistakable too, with leaves distorted and thickened.

And flowers? Rust attacks the under surface of leaves of chrysanthemums, antirrhinums, violas and sweet Williams. The white, frothy cuckoo spit plays havoc, but is easily spotted. Club root doesn’t attack only brassicas – stocks and wallflowers sometimes come under fire, as their swollen roots will testify. Leaf miner causes blisters on leaves. Ealworm turns the leaves of chrysanthemums, dahlias, asters and delphiniums black.

Roses have a host of enemies: capsids, which puncture leaves; aphids, which suck the buds; leafcutting bees, slugworm, black spot, mildew and rust all attack leaves. A weekly inspection of roses is a ‘must’ with leaves turned to see that no dirty work is going on beneath.

Under glass the situation is easier and most diseases can be controlled by proper ventilation. The usual troubles are mildews and moulds. Tomatoes, though, are susceptible to blossom end rot, caused by dryness; greenback, which can result from excessively hot conditions; and leaf mould, the product of poor ventilation. Greenhouse pests include ants, aphids, capsids, earwigs and mealy bugs, but all these and others can be controlled with sprays or insecticidal smokes.

House plants and their troubles deserve a mention. Why do they die? Over-watering is probably the most common cause of failure, although extremes of temperature, draughts, and too little or too much light (depending on the plant) all take their toll. Therefore it’s necessary to study their likes and dislikes – and remember, house plants need moist air more than warm air if they’re to thrive. Attacks from pests are fairly rare, but it happens, so be on guard against greenfly, red spider mites, ants, white flies and scale insects, which cling to plant stems.

In conclusion – never use pesticides on plants when bees are around working the flowers. Clean all equipment after use and wash your hands. Pesticides are never dangerous provided they’re used to the manufacturer’s instructions, so read them carefully, including the small print, before you use them. When you’ve finished, stand the containers out of children’s reach or, better still, lock them up. It doesn’t take a second and it might avert a tragedy.

Experiments are constantly in progress, chemical compounds are manufactured, and efforts are being made to produce plants of all kinds which are immune or can resist the onslaught of pests and disease. Nevertheless, garden foes still come in terrifying numbers—too numerous for us to illustrate fully. Here at least, though, are some of the most common types of the enemies at the garden gate and what they can do. Keep your eyes open and watch for:


Greenfly on Rose bud

Big bud on black currants

Woolly aphis on apple trees

Mildew on rose

Potato blight

Club root on cabbage plant

Black fly on broad beans

Caterpillars of cabbage white butterfly

Capsid bug damage on apple

Peach leaf curl

Black spot on rose

Apple scab

‘Be on your guard and catch them in time’ is the rule.

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