Black Spots

What to look for

Roses can be particularly susceptible to this disease during times of stress, when the health of the plant declines. It’s a soil borne fungus, that attacks leaves causing dark blotches, yellowing and defoliation. 

What to do

Like any disease, prevention is better than cure and it’s important to build up the health of the plant so that they are in a stronger state to fight the disease. 

A regular application of sulphate of potash - about 100 to 150 grams per bush about four times a year – will go a long way in thickening up the cell walls of the leaf for a healthier plant. You could also apply a generous feed of an organic based rose fertiliser every six to eight weeks throughout the growing season. 

While there are many sprays on the market to treat black spot, an alternative natural spray can also be made. Try using two teaspoons of bicarb soda in five litres of water and then add a couple of drops of detergent or seaweed extract and apply using a handheld sprayer.

Aphids

What to look for

Masses of small sap-sucking insects – generally 2-4mm long – laying on buds, stems and leaves, with a sticky residue that attract ants and damage the plant.

What to do

Squirt buds off with water jet or brush them off using a small brush or your fingers. 

Increasing the ladybirds, lacewings and wasps’ population in your garden can also be an excellent natural remedy.

Eco-Oil is a good organic insecticide, effective on aphids and other bugs, but safe on beneficial insects.

Some other natural spray remedies include soapy water (1tbsp liquid soap per quart of water); baking soda spray (1tbsp baking soda in 4l water and 2tbsp of canola oil; essential oils blend (4-5 drops each of peppermint, clove, rosemary and thyme in water).

Powdery Mildew

What to look for

it’s a rapidly spreading fungus that lies dormant until the right conditions appear: warm and humid weather.

Powdery mildew looks like a white, greyish powder spread over the surface of rose leaves. Masses of spores are spread by wind, water splash and insects, making it a particularly virulent disease. The good news is that it is host specific so it can’t be transferred from one plant type to another.

What to do

Organic preparations you may like to try include potassium bicarbonate which has the unique benefit of killing spores on contact. Like baking soda (sodium bicarbonate), it can be made into a solution by mixing a teaspoon of potassium bicarbonate with half a tablespoon of horticultural oil (to spread) and a litre of water which is then sprayed onto the plant.

Another excellent approach to reducing powdery mildew is dusting sulphur on the plants – which is also the best product to control mites. When applying, the temperature must be at least 25 degrees or more for it to be effective.

Modern roses are more disease resistant

Just as prevention is the best cure for diseases, the varieties you select for your garden play a crucial role in keeping pests and problems at bay. 

During our recent journey across Europe, visiting leading breeders like David Austin and Delbard, we discovered that today’s breeding programs prioritize two key features: fragrance and robust disease resistance. 

Modern roses are designed to be clean, low-maintenance, and significantly more resilient than popular varieties introduced years ago. They are engineered to withstand various fungal threats, endure less-than-ideal weather conditions, and fend off insect invasions with ease. 

This is why, at Wagner's, we are becoming increasingly discerning with older varieties, choosing the latest releases instead. 

Each year, we clean our Catalogue of varieties known to be susceptible to fungus and other issues, replacing them with modern, stronger, and safer options.

2026 Releases will be announced soon!

On next Newsletter, we'll introduce our 2026 Catalogue and some of our beautiful New Releases - How exciting!

Stay tuned and connect with us on Facebook and Instagram for updates. 

Our huge selection of potted roses will be back online by the end of the month, with many new varieties and standards available.

Did you know that we regularly post photos and updates through our Facebook and Instagram pages? 

Hop on over and give us a Like!

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