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
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
· 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
· 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
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
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.
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
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
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
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
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
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
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.