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.

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.

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

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 - 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 - 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 - 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 / 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.

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