Nothing latches onto wet, muggy conditions more than a plant disease or two – and so far, this September's weather has provided the perfect environment for them.
Of course, there are plenty of garden plant pests to watch out for this month – but soggy soil and balmy temperatures can play host to a number of plant diseases, all of which can wreak just as much havoc on your garden.
To help you prepare for (or prevent) the worst, I’ve tracked down the most common plant diseases you’ll need to watch out for in September, and the best ways to keep infections at bay.
1. Powdery mildew
Powdery mildew on plants is one of the most common problems you’ll stumble across in September, especially when conditions are as damp as recent weeks.
‘As the weather becomes wetter, the damp can get trapped between plants, causing plant diseases like powdery mildew,’ explains Chris Bonnett, owner of Gardening Express. ‘This is a fungal disease that appears as a white powdery coating on leaves, typically resulting from humidity and poor airflow.’
To reduce the chances of your plants contracting powdery mildew, Chris recommends spacing your plants well (overcrowding is a breeding ground for the fungus), and avoiding overwatering them wherever possible. Sprays like Westland Fungus Guard, £6 at Amazon, can also help control powdery mildew.
2. Blight
If you’ve ever grown your own tomatoes or potatoes, you might already be familiar with blight – the dreaded plant disease that spreads fast and deals a lot of damage. It’s identifiable by dark leaf discolouration and rotting fruit.
It’s one of the worst plant diseases to watch out for in September, according to Thompson & Morgan’s quality control and nursery manager, Kris Collins.
‘September’s damp nights and warm days create prime conditions for blight on tomatoes and potatoes,’ he says. ‘Keep air flowing around your plants and remove affected leaves quickly.’
A pair of the best secateurs will be your best friend in the fight against blight, but make sure you know how to clean your garden tools properly afterwards to avoid infecting other plants. Jeyes Fluid Outdoor Cleaner, from £6.95 at Amazon, is a popular disinfectant.
3. Rust
Rust is one of the most common problems for roses, and frustratingly, it’s particularly rife in September. It’s easy to identify, though, thanks to its name.
‘Rust presents as orange, yellow or brown pustules on leaves,’ says Chris from Gardening Express. ‘It weakens plants and spreads quickly through spores, so maintaining good hygiene and air circulation is key to prevention.’
Prevention is better than cure when it comes to plant rust, and spraying your plants with an eco-friendly solution like the Bronte Heritage Collection Plant Disease Defence Spray, £11.99 at Amazon, can boost your plants’ natural immune system.
4. Botrytis
More fungus! Botrytis, more commonly known as grey mould, is another plant disease to keep an eye out for in September. If you notice a fuzzy, greyish-brown mould on flower buds and foliage, your plant has likely fallen victim to the condition.
‘In ornamental borders, botrytis (grey mould) can appear,’ warns Kris from Thompson & Morgan.
‘Good hygiene is key: remove affected leaves promptly, increase airflow around plants, and avoid overhead watering late in the day.’
In fact, overhead watering is one of the most common garden watering mistakes you can make.
5. Root rot
One of the worst signs you’re overwatering your plants is root rot – and with the heavy rain that’s hit our gardens over the last few weeks, the chances of your plants going down with the condition are a lot higher right now.
‘Root rot is caused by overwatering and poor drainage, which leads to yellowing leaves and mushy roots,’ explains Chris from Gardening Express. ‘This can be avoided by using well-draining soil and watering carefully.’
Luckily, there are plenty of ways to improve drainage in a garden – and if you’re growing plants in containers, there are various ways to fill the bottom of a large planter. Some horticultural grit like Westland Potting Grit, £11.99 at Amazon, can improve soil drainage, too.
Do you have any tricks for keeping plant diseases at bay in September?
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