Protect your garden by spotting and managing diseases
Caring for your garden occasionally involves dealing with diseases that attack your plants.
Here's our advice on how to identify the culprits, treat the diseases and protect your garden to keep your flowers, fruit and vegetables, shrubs and trees in good health.
Tools & materials required
How to identify and treat plant diseases
You might need:
- Cutting and pruning garden hand tools - find the right ones for your gardening jobs with our buyer's guide
- Watering can or sprayer
- Fertiliser and plant food
- Greenhouse ventilation
- Outdoor disinfectant
Common plant diseases you may find in your garden include:
Rose black spot
A disease that causes black spots to appear on rose leaves, some rose varieties are more resistant to it than others.
Cut off spotted stems when pruning and be sure to burn, not compost, any fallen leaves. Repeatedly treating with an anti-fungal spray like Rose Clear Ultra will also help.
This is a grey powdery coating that appears on the leaves of roses and other plants. Like rose black spot – some varieties are more resistant than others.
Mulching, balanced feeding and regular watering will help get rid of this unattractive disease.
Often found on pelargoniums and other plants that are kept in a greenhouse over winter to avoid the cold, grey mould can also attack soft bedding plants or perennials in humid conditions and rot strawberries in wet summers.
Improving the ventilation should help decrease mould so why not add some auto vents or louvre windows to your greenhouse? Additionally, pick off any mouldy leaves and burn them.
A fungal infection, this will wilt your clematis and can kill it over time. Keep your eyes out for wilting as well as blackened leaves or stems.
To protect it, plant the clematis with the base of the stems 5 to 10 centimetres (cm) below ground – this way the roots will re-shoot if the top of the plant dies. It also helps to mulch, as this keeps the roots moist and cool.
If you see any signs of wilt, cut all the impacted stems back to healthy growth and burn anything you remove.
This disease enters trees through damaged tips and cuts (fruit trees are particularly prone), quickly turning the leaves brown and killing the tree if not dealt with quickly.
If one of your trees develops Fireblight treat it quickly to prevent the disease spreading to other trees.
Peel back the bark on the infected branches to reveal the brown staining underneath. Cut back to healthy wood (up to 30cm in smaller branches and up to 60cm in larger ones) and burn anything that is removed. All secondary, late blossom should be removed before they open.
This disease attacks fruit, turning it brown with white spots.
As it spreads by contact, pick off any affected fruits and burn them. And don't forget to collect any that drop onto the ground and burn them too.
So called because it forms rust-like orange pustules, this species-specific fungal infection effects mint, roses and hollyhocks, among others.
Regularly treat by spraying with anti-fungal treatment, like Fungus Clear, throughout the summer months.
This effects seedlings and cuttings, especially in greenhouses – the base of the plant goes black, they collapse and die.
Damping off is usually caused by poor hygiene, lack of ventilation and overwatering. To reduce risk, sow seeds sparsely and drench the soil around them (and cuttings) with a copper-based fungicide.
How to prevent plant disease
You might need:
The healthier and stronger a plant is, the less likely it is to become unwell. There are very few plants that like extreme conditions, and it's usually during one of these periods of drought, or lots of rain that many plants weaken and become susceptible to problems.
Plant in the best area
Providing your plants with a happy home from the moment you plant it, is the easiest way to help them avoid infection. So keep them as healthy as possible by emulating their natural habitat.
Always read the labels of the plants or seeds you buy to ensure that you're planting them in the right place. For example, plants that like sun or partial shade in moist soil will be weakened by being planted in a shady, dry area.
If you’ve previously lost a plant to disease, check that it’s suitable to replant in the same spot. We advise avoiding that spot for that species, and if not possible, change the soil.
Feed and water regularly
If it’s particularly dry, even in winter, ensure your plants have access to water. A thirsty plant will be weakened and more susceptible to infection.
All plants need nutrients to flourish and making sure your plants are fed regularly will help them stay strong. This is especially important for plants in containers, as the nutrient value in compost will only last for around six weeks – after that they're reliant on you to provide food.
Keep things clean
Clean pruning tools every time you use them with outdoor disinfectant like Jeyes Fluid – this will stop the spread of infection.
And always clear up and burn any leaves, plants or wood that you believe have been infected – do not add these to the compost heap.