Keep up to date with the latest offers and information on Garden Pests & Diseases with Let's Go Gardening on Facebook

Garden Pests & Diseases
Pests are animals that cause damage to plants and crops. They may damage or destroy sections of or entire plants. Some pests are well known such as slugs and snails. They are easily recognised and often swiftly dealt with. However lesser known pests can cause just as many problems. Pests can feed on a plant often devouring great sections or they can spread diseases that can prove fatal for the plant.

The tip to preventing infestation is to always buy healthy plants. Any plant that is discoloured or wilting may already have have problems. Once a healthy plant is rooted correctly in the right place and things such as soil ph and temperature have been taken into account if problems arise the first step is to identify the cause. Knowing what you are dealing with is necessary in finding a solution.

There are many ways in solving pest problems the trick is to find which one suits your plants needs best.

Organic & Biological Pest Control
Organic control helps plants to resist and recover from pest attacks using natural methods. Organic mixtures such as soft soap and sulphur dust are safe to use but cannot be used frequently. They deal with apparent pest problems on contact and are not suitable for large surface areas.
Organic traps can be erected as long as you know which pest you are fighting. Earwigs can be trapped in flower pots filled with grass or straw and placed on a stick. Smearing yellow paper with a sticky substance will attract whiteflies as they are drawn to the colour yellow.

Companion planting is used to either repel pests or to beckon natural predators. Planting such plants in between pest ridden areas can dramatically cut down pest attacks. Planting strong smelling herbs (garlic, rosemary) may deter pests from coming near plants in that area. Finding out which plants the natural predator you need prefers is also beneficial. By attracting predators such as ladybirds and predatory mites the pest population should be kept down.
Pest Prevention Companion Planting
  Basil - Repels flies and mosquitoes
  Horseradish - Deters potato bugs
  Mint - Deters white cabbage moths and ants
  Peppermint - Repels white cabbage butterfly
  Rosemary - Deters cabbage moth, bean beetles and carrot fly
  Garlic - Deters Japanese beetle
  Sage - Deters cabbage moth and carrot fly
  Thyme - Deters cabbage worm
Plants that are resistant to pests are widely available. Plant breeders have produced cultivated plants that are more capable of dealing with pests than their relatives. In many cases the plant continues to resist attacks however factors such as the weather or growing conditions can weaken the plants defences.

Keeping on top of your garden chores is another effective way of keeping good pest control. Being vigilant and catching pest attacks early gives you more time for damage limitation. Regular removal of infested plants will control many infestations. Any debris should be burned or discarded immediately and not composted.

By rotating vegetable crops regularly you can prevent pests that are soil-borne.

Encourage animals into your garden as many help get rid of pests. Hedgehogs and frogs feed on many pests that can cause damage. Birds often eat pests so introducing bird boxes and feeding stations encourages them to stay in your garden. Centipedes also feed on pests. Spiders webs catch many insects. Ladybird adults and larvae feed on aphids. Ants and wasps also help keep down pest attacks.

Aphids (Photo: Daniel Flohr -

Garden Friendly Creatures
  Ladybirds and their larvae will eat aphids such as greenfly and blackfly and also mites, scale insects and some small caterpillars. Encourage them by having a patch of nettles or honeysuckle on which they will find plentiful amounts of aphids to feast on and having plant debris in which they can hibernate.
  Hoverflies, which are sometimes mistaken for wasps due to their colouring, have larvae that will eat up to 50 greenfly a day. They also eat spider mites and small caterpillars. Mature hoverflies eat nectar and pollen. Encourage them by growing plants that are yellow or gold in colour.
  Dragonflies will eat mosquitoes thus keeping the number down.
  Spiders catch flying pests in their webs. Provide areas for them to spin their webs safely.
  Lacewings, beetles, centipedes, predatory mites, hedgehogs, frogs, toads, newts, glow worms and birds all play an important role in keeping your garden pest free too.
Biological Control

Biological control is using natural predators to keep down the number of pest attacks on your plants. Usually used mainly in greenhouses where pests have developed some level of immunity to chemicals. In gardens where pesticides are used widely they cannot only kill the pests but also the predators you have introduced. By identifying what pest you have on your plants you can then introduce the best predator for the job.

Many pests have now developed such a high immunity to chemical control that biological control is often the only answer.


Chemical Control

Using chemical aids sparingly can also be extremely effective towards fighting pests. By combining chemical and organic control your garden should be relatively pest free. Pesticides work by killing pests when they are either sprayed directly or walk over a treated area. However as many pests are becoming immune it is not always effective.

Checking your pesticide label is a must as some plants have an adverse reaction to them. The majority of products should have a list of plants that are not to be treated. Always perform a test on a small area before spraying the entire plant.

Garden Diseases

A plant disease is defined as any condition caused by organisms such as fungi, bacteria and viruses. In almost all cases the health and growth of the plant is affected and in some cases the plant dies.

As with cultivated pest resistant plants there are disease resistant plants that are widely available. For example some roses are resistant to powdery mildew, rust and black spot.

Well established infections are extremely difficult to contend with so catching them early is a must. Removal of sections or the whole plant is often necessary to prevent the disease from spreading. Unlike pest infected plants it is not wise to compost your infected plants but instead burn or discard them. This includes fallen leaves that are infected. Always clean your pruning tools after use.

It is also worth getting rid of the top soil around the plant especially if you wish to replant with the same genus.

Fungicides can be used to minimise disease. Contact fungicides may kill fungal spores and prevent spreading but are almost useless on established infections. Systemic chemicals work by being absorbed into the plant. Fungi is then killed from the inside out. Overuse of fungicides can promote immunity in some diseases.

Avoid spraying pesticides or fungicides on plants in direct sun, or when they are dry as this will prevent damage to the plant.


Garden Hygiene

Remove the remains of old, rotting or infested plants properly. Dig up & destroy those with virus symptoms so that the problem does not spread to other plants. Keep on top of weed control, particularly near the vegetable plot because weeds often act as a host for pests.

Plants growing too close together compete for light, water & nutrients and cannot grow to their potential. Overcrowding also prevents good air circulation, allowing fungal diseases to take hold.

Take care not to damage plants, lesions & cuts  on plant tissue can be an entry point for disease. Use sharp tools for pruning and make clean cuts just above a bud to prevent die back. Check the stakes & ties on trees & shrubs, they must be secure so that they don't rub & damage the plant.

In the warm conditions inside a greenhouse, young plants are particularly vulnerable to attack. Raise seeds, cuttings & young plants in clean pots. Use fresh compost and tap water rather than rain water. If you have a water butt for watering your plants with rainwater, empty & clean it out once a year.


Disease Watch

Spring - Buy varieties of plants that are resistant to pests & diseases. Look for the first signs attack.

Summer - Diseases can often take hold when plants are overcrowded, so space accordingly and ensure good air circulation.

Autumn & Winter - Clear fallen leaves & burn any that show diseases. In the greenhouse maintain good ventilation to avoid grey mould. Clean greenhouse & equipment with garden disinfectant.


Blackspot Blackspot - A common fungal disease that attacks plants  leaving pale and dark spots on the leaves. Prune away all affected leaves and burn them. Spray roses in winter with an anti black spot remedy or tar-oil wash. In early spring spray with a rose fungicide or with sulphur and mulch the ground at the base of the plant with compost.
Mildew Mildew - A grey white powder on leaves and buds. Severe attacks can cause leaves to fall. Mildew is brought on by dryness or lack of nutrients. Spray with a rose fungicide or with sulphur at the first signs of attack. Water and feed your affected plant more often and mulch around the base.
Rust Rust - A problem in mild and wet summers. Orange postules develop of the underside of the leaves and can cause premature defoliation. Spray with a rose fungicide that works on rust, or use a fungicide containing myclobutanil.
Grey Mould Grey Mould / Botrytis - Fuzzy grey fungal growth on foliage. This causes discolouration and rapid deterioration. Infection may spread to plant. Plants affected are perennials, annuals, trees, shrubs, fruits, vegetables and indoor plants. Venerable plants are those with soft leaves.
Phytophthora ramorum and Phytophthora kernoviae
Phytophthora ramorum and Phytophthora kernoviae are fungus-like pathogens which can kill some types of shrubs and trees, such as the European beech, and pose a threat to garden plants, woodlands and native heathland.

Related pages..

Vine Weevil Vine Weevil


Let's Go Gardening - Garden Pests & Diseases

A - Z Sitemap Contact Us Send us your pictures

Let's Go Gardening - Garden Pests & Diseases

Links & Resources Advertising Join us on Facebook
Cookies & Disclaimer Link Exchange Gardening Shop UK

web counter

Let's Go Gardening - Garden Pests & Diseases

Let's Go Gardening and are trading names of Shaw Media. Registered in England and Wales. Company No. 07492950