Gardeners are being urged to treat roses with a natural kitchen staple this autumn to combat black spot, a widespread fungal disease that can disfigure plants with dark patches, yellowing leaves and premature leaf drop. The Royal Horticultural Society (RHS) identifies black spot as the most serious disease affecting roses.
A badly affected rose can lose a large proportion of its leaves, reducing the plant's vigour. If roses have fallen victim to black spot over the summer, autumn is an ideal time to begin clearing away affected foliage. One popular home remedy, shared on the Gardening Hints and Tips Facebook page, involves using diluted milk.
Milk remedy backed by gardeners
Karen Powell posted a photograph of her flourishing pink rose on the Facebook page, with the caption: "Here's how your rose will look when you control black spot with diluted milk. Water it at the base every two weeks. It gives nice green glossy leaves. It also helps feed them."
Cow's milk contains natural proteins and enzymes with antifungal properties capable of destroying the spores. Milk proves most effective when exposed to sunlight, as it generates an environment less favourable to fungus and can help form a fine coating that prevents spores from adhering to the plant.
Fellow gardeners endorsed the hack enthusiastically, while others suggested baking soda as an alternative. Lou Deane wrote: "I use my nearly empty milk cartons. Fill them up with water and empty onto the roses at least once a week."
RHS recommends hygiene-first approach
The RHS also advocates a chemical-free approach, which can begin in autumn by gathering fallen leaves. They said: "If practical, pick off and dispose of any leaves that remain on the plant over the winter months. Prune out all stem lesions in spring before leaves appear."
These actions will help delay the onset of the disease, but are of limited value because spores are bound to blow in on wind-blown rain from elsewhere. Keeping black spot under control can also contribute to healthier roses over a longer period, enabling them to retain foliage and keep flowering well into early autumn.
Homemade remedies alone should not be relied upon, with thorough garden hygiene considered the most effective first line of defence. Removing diseased material, clearing away infected fallen leaves, and avoiding conditions where foliage stays damp for extended periods are all essential steps. As autumn progresses, tackling the disease promptly is crucial in helping to prevent black spot from taking hold again the following year.
