How To Control Disease, Weeds & Pests

  • This guide will outline and show what problems you might deal with when maintaining your garden.
  • Learn how to deal with diseases of all kinds and the best way to spot and remedy them.
  • Find out how to manage weeds, and the products that might be best for each kind, and when you can find them.
  • Pests are always troublesome, so this guide walks you through the ones you might encounter and solutions in order to prevent them damaging your plants.

Controlling Weeds & Garden Pests

Wouldn't it be great if once the garden was designed and planted that maintenance wasn’t needed? Unfortunately we all know this isn’t the case. This guide will outline what problems may be seen and how to treat or deal with them.

Weeds are a problem because they compete for the same soil and the nutrients within it, sunlight and water that are intended for those plants specifically placed in an area within the garden.
Weeds are a problem because they compete for the same soil and the nutrients within it, sunlight and water that are intended for those plants specifically placed in an area within the garden.

Disease

When dealing with all living things disease can always be present diseases are caused by either bacteria, virus or fungus and can have a limited or devastating effect, even killing plants in extreme cases when left untreated. Diseases can affect all growing stages of plants and all areas of it from the roots to the flowers, sometimes affecting the whole plant and sometimes just part of it.

The three most common plant diseases founds in the garden are:

Powdery Mildew – As its name suggests this leaves a grey powder effect on leaves. It can affect many plants but principally roses, with some modern varieties bred for resistance. To prevent Mildew, general maintenance is needed including regular watering and feeding avoiding over wetting of the leaves. The application of mulches below the plant may also help.

Black Spot – Again predominantly a rose problem, this causes black spots on the leaves of the plant. Black spot is a very prolific disease and again rose breeders have tried to develop more resistant varieties to help stem the problem. Affected leaves and stems should be removed and destroyed. If they are not destroyed there is a risk of the disease spreading from these removed leaves and stems. Sprays are available to combat black spot.

Rust – Orange globules are formed by this disease on the underside of leaves, although they can be found on other areas of plants. Roses are particularly affected but also mint and hollyhocks. To treat this problem needs chemical intervention with regular spraying throughout the growing season with a relevant fungicide. Groundsel, a common garden weed is a particular common host of rust so the removal of any groundsel in the garden will help reduce the chance of your plants developing rust.

Diseases are difficult to prevent and some gardens may be particularly susceptible to certain plant diseases because of their location, the climatic conditions and the history of the site and its soil. However there are certain things you can do to try and reduce the incidence of contracting plant diseases. Firstly choose disease resistant varieties if at all possible. Most plants when sold now have an outline of the diseases they are susceptible to or whether they have any resistance to them. If in doubt ask an assistant who will be able to advise you on the correct choice of garden plant.

Routine hygiene and housekeeping is also essential. As in human cases disease often results from a period of stress and this is also true for plants. By keeping them fed, watered and weed free the incidence of disease will be significantly reduced.

To treat plant disease in its early stages simply removing and destroying the affected area of the plant may suffice. However if chemical intervention is needed a systemic product must be chosen. This is one which will be absorbed by the leafy areas of the plant and carry the chemical right down to the roots. They will not affect the soil but will destroy any plant they have contact with so care is needed when applying the product.

Weeds

Weeds are foreign plants i.e. they are plants not intended to be where they are. Weeds are a problem because they compete for the same soil and the nutrients within it, sunlight and water that are intended for those plants specifically placed in an area within the garden. Some cause little harm but other more aggressive weeds can destroy areas of a garden rapidly especially in the spring and early summer months.

Garden Weeds

The most common perennial garden weeds are:

  • Dandelions
  • Bindweed
  • Creeping buttercup
  • Nettle
  • Ground elder
  • Horsetail

The most common annual garden weeds are:

  • Groundsel
  • Bittercress

As with diseases weeds are difficult to eliminate and regular maintenance is the best form of defence. The removal of weeds little and often will help prevent establishment and spread and it is paramount not to let the weeds develop to the seed producing stage.

The application of anti weed material can also help. By laying weed control fabric before planting a bed will provide a defensive wall to prohibit weeds and the use of mulches and/or chipped barks on beds around plants will also provide a deterrent to weeds.

Pests

Garden pests can take many forms with insects, birds and animals all providing a threat to healthy and successful plant growth. Healthy plants tend to be resilient to some pest damage but action should be taken if the pests are in danger of becoming out of control.

Slugs and Snails are perhaps the most commonly recognized garden pest and can happily munch away your whole garden if left untreated!
Slugs and Snails are perhaps the most commonly recognized garden pest and can happily munch away your whole garden if left untreated!

Slugs and Snails – These are perhaps the most commonly recognized garden pest and can happily munch away your whole garden if left untreated! Control methods vary from simply picking them off plants and the ground to chemical or barrier methods. Slug pellets are readily available but extreme care should be taken with these as they are poisonous to wildlife and where children play in gardens they are not recommended. It is essential to follow the guidelines when using slug pellets. Upturned grapefruit skins and beer traps sunk into the ground attract slugs which can then be routinely removed in a more natural way and the laying of gritty material such as sand and grit around the base of plants will also provide an effective deterrent.

Insects – The list of insect pests in the garden is extensive and includes wasps on fruit crops, caterpillars on vegetable crops and aphids and whitefly on a whole range of plants. Vine weevils are also a pest. Removal of these insects is most effective when using nature to reduce them. For instance wasps can be lured into traps filled with sugary bait and the attraction of birds into your garden will keep caterpillar numbers down. The introduction of ladybirds, lace wings and hoverflies will all reduce the aphid population as will nematodes particularly in war locations. These are tiny worm like predators which will feed on insects. Vegetable plants can also be protected by planting strong scented flowering plants in near proximity, with marigolds being extremely effective at this control method. Chemicals can also be used i.e. pesticides although these will destroy all insects and not select out the good from the bad.

Animals – A whole variety of animal can be regarded as garden pests from the over exuberant dog to the neighbour’s straying cat, each individual garden will have its own hit list of animal problems. Cats can be deterred by using cat repellents of by using strong scents where they tend to use the garden as a toilet. Citrus peel or moth balls are recommended here. Wild animal such as deer or badgers can also present a problem. Badgers are protected and therefore should be encouraged to explore other areas and not your garden. Badgers have been known to destroy fences and barriers to gain access to their usual foraging grounds so simply re-fencing the area will not solve the problem. Height of fences is the main deterrent for deer, a fence of over 2.5m is recommended. A new development is the sonic repellent which emits a high pitched sound that the target animal can detect and finds irritating encouraging them to find alternative foraging areas. These are now available for many animals from cats to moles.