One of the most distressing sights is to see a whole crop of vegetables destroyed – eaten by pests rather than by you. Insects and other small creatures cause damage in the flower garden which is unsightly – on food plants they are destroyers. Diseases, too, can cause havoc. Most diseases are caused by fungi and these can often be prevented by spraying with a fungicide. The others, caused by bacteria and viruses, can rarely be controlled in this way.
Not all vegetable troubles are caused by pests and diseases – split tomatoes, blown sprouts and bull-necked onions do not appear in the pest charts but they are still the effects of important disorders. The purpose of this is to tell you how to avoid troubles of all types and to help you to identify and control the pests, diseases and disorders which can attack a wide range of plants.
It is not the intention here to frighten you – no matter how long you garden you will never see all of these troubles. The role of these guides is to take away the worry of the unidentified problem, and to provide you with the knowledge to deal with the trouble speedily and correctly.

Prevent trouble before it starts
· Choose wisely. Read about the crop before you buy – don’t rely solely on the seed packet. Make sure that the variety is suitable for the chosen sowing date and don’t leave your purchase to the last minute – many select varieties sell out early. Sometimes you will need to buy seedlings instead of seeds for transplanting into the plot. Choose carefully – the plants should be sturdy, free from disease and discolouration and there should be a good root system. Here you must leave it to the last minute because there should be as little delay as possible between buying and planting.
· Prepare the ground properly. Good drainage is vital – a plant in waterlogged soil is likely to succumb to root-rotting organisms. Follow the rules for the correct way to manure, feed and lime the soil – remember that vegetables vary widely in their soil needs. The time for digging is autumn or early winter if you plan to sow in spring.
· Rotate your crops. Soil troubles and nutrient deficiencies can build up if you grow the same crop year after year on the same site. Crop rotation is necessary for successful vegetable production.
· Avoid overcrowding. Sow seed thinly. Thin the seedlings as soon after germination as practical – overcrowding leads to crippled plants and high disease risk. Do not leave thinnings on the plot – put them on the compost heap or burn if instructed to do so.
· Get rid of weeds and rubbish. Weeds rob the plants of water, food, space and light. Rubbish, like weeds, can be a breeding ground for pests and diseases.
· Get rid of badly infected plants. Do not leave sources of infection in the garden. Remove and destroy incurable plants when told to do so.
· Feed and water correctly. Some plant troubles are due to incorrect feeding and soil moisture problems. Use a balanced fertilizer containing nitrogen, phosphates and potash – follow the instructions. Never let the roots get dry but daily sprinklings instead of a good soaking may do more harm than good.

Deal with trouble as soon as you can
· Keep a small plant-aid kit. It may be several days before you can get to a garden shop because of holidays, weekends, etc. but a sudden attack by blackfly, caterpillars or slugs calls for immediate action. It is therefore a good idea to keep a small selection of pesticides in the garden shed for emergency use. You will need a packet of Multiveg for above-ground pests and diseases, Bromophos for below-ground pests and Slug Guard for slugs.
· Spray when necessary. Inspect the plants regularly and at the first sign of trouble look up the cause in the appropriate section. Once you have put a name to the problem, act quickly – many pests and diseases can be checked quite easily if treated promptly, but may be difficult or impossible to control if left to get out of hand.
There are a few simple rules to ensure effective, safe and economical pest control. Read the label carefully and make sure that the product is recommended for the plants you wish to spray. Follow the instructions – do not make the solution stronger than recommended and never use equipment which has contained a weed killer.
Try to pick a day when the weather is neither sunny nor windy and apply a fine forceful spray until both sides of the leaves are covered and the liquid has just started to run off. After spraying, wash out equipment and wash hands and face. Store packs in a safe place and do not keep unlabelled or illegible packs. Never store pesticides in beer bottles or similar containers.
Correct timing is important. Insecticides are normally applied at the first sign of attack. Systematic products such as Long-last go inside the sap stream and protect parts not reached by the spray. Fungicides usually work as protectants and so they need to be applied before trouble appears.
Some problems (red spider mite, whitefly, diseases, etc.) need repeated spraying. Once again follow the instructions on the label. Finally, choose a product with a suitable harvesting interval – during the picking season choose a chemical with a 0-2 day interval between spraying and gathering.

General disorders
Some vegetable troubles attack a single or small group of crops – examples are potato blight, carrot fly and pea moth. Other problems can attack a wide range of plants and these are the general disorders and general pests and diseases.
Wind: Wind is often ignored as a danger, yet a cold east wind in spring can kill in the same way as frost. More frequently the effect is the browning of leaf margins. Another damaging effect is wind rock, which can lead to rotting of the roots.
Frosts: A severe late frost will kill half-hardy vegetables. The shoots of asparagus and potatoes are blackened, but healthy shoots appear after the frosts have passed. The general symptoms of moderate damage are yellow patches or marginal browning of the leaves. The basic rule is to avoid sowing or planting before the recommended time unless you can provide protection. If your garden is on a sloping site, open part of the lower boundary to air movement so as to prevent the creation of a ‘frost pocket’.
Shade: In a small garden deep shade may be the major problem. Straggling soft growth is produced and the leaves tend to be small. Such plants are prone to attack by pests and diseases. Grow leaf and root types rather than fruit and pod vegetables.
Too little plant food: The major plant foods are nitrogen, phosphates and potash, and a vigorous crop acts as a heavy drain on the soil’s resources. Nitrogen shortage leads to stunted growth, pale leaves and occasional red discolouration. Potash shortage leads to poor disease resistance, marginal leaf scorch and produce with poor cooking and keeping qualities. Before sowing or planting apply a complete fertilizer, such as Growmore fertilizer, containing all the major nutrients. One or more dressings should be applied to the growing plants. Backward vegetables are helped by a leaf-feeding fertilizer such as Fillip.
Trace element shortage: Vegetables often show deficiency symptoms such as yellowing between the veins and leaf scorch. The most important trace elements are magnesium, manganese, iron, molybdenum and boron. Make sure the soil is well supplied with compost or manure. If your soil is known to have a trace element deficiency problem, undoubtedly the best answer is to water the garden early in the season with MultiTonic – a product containing all the trace elements required by plants in Britain.
Too Little Organic Matter: The soil must be in good heart and this calls for liberal amounts of organic matter. Not all materials are suitable; peat may increase aeration and water retention but the need is for an active source of humus. Good garden compost and well-rotted manure are ideal. Timing is all-important – look up individual crops for details.
Too little water: The first sign is a dull leaf colour, and this is followed by wilting of the foliage. Discolouration becomes more pronounced and growth is checked. Lettuces become leathery, roots turn woody and some plants run to seed. Flowers and young fruit may drop off. If water shortage continues, leaves turn brown and fall, and the plant dies. Avoid trouble by incorporating organic matter, by watering thoroughly and by mulching.
Too much water: Water logging affects the plant in two ways. Root development is crippled by the shortage of air in the soil. The root system becomes shallow, and also ineffective as the root hairs die. Leaves often turn pale and growth is stunted. The second serious effect is the stimulation of root-rotting diseases. Good drainage is therefore essential, and this calls for thorough autumn digging. Incorporate plenty of organic matter into heavy soil – the correct timing for humus addition depends on the crop being grown.
Heavy rain following drought: The outer skin of many vegetables hardens under drought conditions, and when heavy rain or watering takes place the sudden increase in growth stretches and then splits the skin. This results in the splitting of tomatoes, potatoes and roots. Avoid by watering before the soil dries out.

General pests and diseases
Aphid: The weakening effect of greenfly and blackfly on leaves and shoots is obvious. There are, however, other damaging results. Sticky honeydew is deposited, and the sooty moulds which grow on it are unsightly and block the leaf pores. Even worse is the danger of virus infection, as aphids are the prime carriers. For these reasons aphids should be tackled quickly. Outdoors spray with Long-last or Crop Saver; under glass use Crop Saver.
Earwig: The leaves of beetroots, parsnips and carrots may be skeletonized by this pest. Spray with Crop Saver when they are first noticed.
Birds: Birds are a joy in the garden and most of them do no harm. A few species, however, are a serious nuisance to seeds, seedlings and some mature crops, and netting is necessary.
Cats: Cats often choose seed beds for toilet purposes, and usually avoid their own gardens. This is a difficult problem and Pepper Dust should be sprinkled liberally where cats are a nuisance.
Damping off: Germinating seedlings can be attacked by the damping off fungi, withering and blackening at the base before toppling over. Indoors use sterilized compost, sow thinly, water carefully, ventilate properly and provide adequate light. Outdoors avoid sowing in cold wet soil, sow thinly and do not over water. If the disease does occur remove the affected seedlings immediately and water remainder with Cheshunt Compound.
Soil pests – Group 1: Controlled by Slug Guard.
Slug Guard, based on methiocarb, is an alternative to metaldehyde for the control of slugs. It has the advantage of being effective in wet as well as dry weather. Research has shown that a light sprinkling raked into the soil surface will control woodlice, millipedes and leatherjackets.
Slugs and snails: Extremely troublesome pests especially in wet weather. Seedlings may be killed; leaves, stems and roots of older plants are damages. Look for the tell-tale slime trails.
Leatherjacket: Dark grey grubs, about 1in (2.5cm) long. Most active in light soils and wet weather. Stems are attacked, lower leaves devoured. Root crops are tunnelled.
Millipede: Pink or black grubs which curl up when disturbed. They attack underground parts of plants, often extending areas damaged by other pests. Most troublesome under cool, damp conditions. Not easy to control.
Woodlice: Grey, hard-coated pests found in greenhouses and frames. Seedlings and young plants are attacked. They hide under pots, rubbish etc. during the day.
Soil pests – Group 2: Controlled by Bromophos
Bromophos can be used for all vegetables without risk of taint. Apply ½ oz per sq yard and lightly rake in.
Cutworm: Fat grey or brown caterpillars, 1 ½ -2in (2-5cm) long. They live near the surface and eat young plants at ground level. Stems are often severed.
Chafer grub: Large curved grubs, over 1in (2.5cm) long. They feed throughout the year on roots and are often a serious pest in newly broken-up grassland
Wireworm: Shiny, slow-moving grubs. They attack a wide variety of vegetables. Stems are gnawed below the ground, root crops are tunnelled.

Pesticide - Minimum interval between Spraying and Harvesting
Multiveg - 0 days
Sulphur - 0 days
Carbendazim - 0 days
Benomyl - 0 days
Thiophanate-methyl - 0 days
Bio Sprayday - 0 days
Permethrin - 0 days
Malathion - 1 day
Derris - 1 day
Crop Saver - 1 day
Pirimicarb - 3 days
Bromophos - 7 days
Slug Guard - 7 days
Pirimiphos-methyl - 7 days
Dimethoate - 7 days
Carbaryl - 7 days
Dithane 945 - 7 days
Long-last - 14 days
Diazinon - 14 days
Fenitrothion - 14 days
Hexyl - 14 days
Lindane - 14 days
Note: One or more crops may require a longer interval – check label.