Roses With Powdery Mildew: Getting Rid Of Powdery Mildew On Roses

Roses With Powdery Mildew: Getting Rid Of Powdery Mildew On Roses

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Those of us who grow and care for roses often encounter a soft whitish coating on our plants’ leaves, stems and sometimes buds. This substance is powdery mildew, known to experts as Sphaerotheca pannosa var. rosae. The powdery mildew fungus shows up more often than we’d like, especially in humid climates or damp environments.

If you think you’re seeing powdery mildew on your roses, take a few minutes to learn why it’s there and what can be done about it.

Identifying Powdery Mildew on Roses

Powdery mildew looks a lot like it sounds – like a fine, soft powder sprinkled on your plant. It’s important to periodically inspect your rose bushes on both sides of the leaves, as well as the stems. This common fungus can spread from the leaves to the stems, and even to the buds themselves. Even worse, it can and will spread to other nearby plants.

Moisture is a friendly environment for rose powdery mildew. It helps the fungus travel from one part of the plant to the next. The powdery mildew fungus can be fairly destructive. Fresh new foliage on a rose bush is its favorite snack, and its presence can cause the bush’s leaves to become deformed.

Left untreated, rose powdery mildew will attack the rose buds, stunting and disfiguring them, and preventing them from opening. Warm, dry days followed by cool, humid nights are the perfect conditions for an outbreak of powdery mildew.

Powdery Mildew Rose Treatment

Be sure you trim away what you can of the powdery leaves and discard them. Make sure all dead leaves, stems and decaying matter are removed from the bush and around its base. Rose bushes need some air to pass through them, so if they’ve grown bushy and bunchy, you should do a bit of pruning.

If you’re seeing just a light case of powdery mildew, you can try spraying it off with water on a warm, dry day. However, it’s good to keep an eye on it, because it’s more than likely to return.

Perhaps the best way to stop the fungus in its tracks is to treat your roses with neem oil. Other organic products on the market that contain potassium bicarbonate are fairly effective as well. There are homemade remedy recipes available on the Internet, such as mixtures of dish soap, cooking oil and baking soda, but they can be harsh and present a fair amount of risk to the plant. Neem oil is probably the safest solution.

Always water your roses at ground level. Water from sprinklers will sit in and on the leaves and buds, which encourages powdery mildew. Also, remember when you’re planting your roses that they like sunshine. Try not to plant them in a crowded or shady environment.

Roses Resistant to Powdery Mildew

There are some varieties of roses that seem to attract powdery mildew. When you shop for roses, try to choose the types that are more disease resistant. Having this designation doesn’t mean your rose bush will never contract powdery mildew, but it will be less likely.

If you’re shopping from a catalog or a local garden nursery, ask an expert and look for notations about the plant’s resistance to disease.

How to Get Rid of Powdery Mildew on Rose Bushes

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Prevention is, of course, the best remedy when it comes to powdery mildew and roses (Rosa). In fact, the disease has probably already started infesting your rose bush even before you see the distinctive white powdery mat of fungus spreading over the leaves of your plant. That said, commercial fungicides and home treatments can be effective in keeping the fungus from spreading. With more than 14,000 different varieties, roses grow in all U.S. Department of Agriculture plant hardiness zones, 1 through 13, depending on the species.

How to Control Powdery Mildew

Keep Your Garden Clean: Powdery mildew spores can overwinter in your garden -- so remove all affected fallen leaves from your garden during and at the end of the season. If you see leaves that are just beginning to show the disease, pluck them off the plant and throw them away to help keep powdery mildew from spreading to healthy plants.

Encourage Air Flow: Powdery mildew loves still, humid conditions, so keep spaces between your plants for air to flow through. Divide perennials every few years to keep them loose and open and prune trees and shrubs so they don't get too thick. Also: Consider airflow when you choose spots for your plants. Avoid planting mildew-prone plants in especially sheltered spots.

Apply Fungicides: Fungicides can effectively control powdery mildew from spreading, but they're not as good at killing the disease once it's established. So use fungicides -- either traditional or organic -- in wet, humid periods before you see a problem or just as the plants first start to show symptoms. Look for these products at your local garden center, nursery, or online.

roses – other powdery mildews affect other plants


Prune out and bin (don’t compost) infected leaves or stems. When buying roses, choose varieties with good resistance to powdery mildew – a reputable grower will be able to advise. Keep the soil around the roots moist at all times. When planting roses, prepare the soil well by digging in generous amounts of well-rotted compost or farmyard manure into the planting hole. For established roses, a thick layer of mulch around the base of the plant will help.


Before symptoms appear, apply a fungicide containing flutriafol at the recommended intervals from early spring.

These fungal diseases can severely stress the plant and diminish its performance, resulting in fewer blooms and a sickly looking plant. However, there are natural treatments available to assist gardeners in fending off these fungal infestations.

What is powdery mildew

Powdery mildew appears on new foliage and buds, first as a series of small white spots, which later become a furry mass of mould. It causes the leaves to wilt and wither and eventually die.

What is black spot

Black spot shows on older leaves as dark, circular marks and eventually the foliage turns yellow and falls to the ground.

Natural treatments for powdery mildew and black spot on roses

Treatment 1: Lime Sulphur

Dilute lime sulphur with water to the manufacturer’s recommendations, and sprayed over the stems and trunk. Apply this in the winter when the plant is dormant.

Treatment 2: Milk and Baking Soda

Organic growers have used milk and baking soda with success. Simply mix half a litre of milk with two tablespoons of baking soda in five litres of water and spray liberally over foliage and stems. This formula can be applied at any time of the year.

Treatment 3: SeaMax® Fish & Kelp

Rose Growers love it so much that SeaMax® Fish & Kelp is officially endorsed by The Qld Rose Society . This BFA certified organic product not only prevents fungal disease, but also fertilise your plants at the same time. Simply mix in a watering can to the manufacturer’s recommendations, then liberally water over the foliage and stems.

Tips for decreasing rose fungal diseases

Tip 1: Spacing

When planting roses it is essential for them to be far enough apart to allow for good air circulation all round. They should be planted in full sun away from other plants that will smother their stems and compete for moisture and nutrients.

Tip 2: Hygiene

Practice good hygiene by cleaning secateurs with a solution of bleach and water between each rose bush never compost prunings and remove any fallen foliage, especially if it is diseased.

Powdery mildew

Powdery mildew disease is common on a wide range of plants. There are numerous forms of powdery mildew, which are specific to one plant or a group of plants, and won't spread to other plants. For instance, rose powdery mildew attacks roses, clematis powdery mildew attacks clematis - they won't spread to each other.


Powdery mildew, as the name suggests, is a powdery fungus that grows mostly on the upper surface of leaves. It is usually white in colour. It will occasionally spread to the underside of leaves and other parts of the plant, such as stems and sometimes flowers and fruit.

Powdery mildew prospers in dry soil conditions, but where the overhead conditions are somewhat humid or damp.


Leaves, particularly of young infected plants, may turn yellow and become distorted and finally turn brown. Infected areas and indeed whole leaves will gradually die back and dry off.

On rhododendrons, the fungal growth is still powdery but maybe beige in colour and may occur more frequently on the underside of the leaf.

Treatment and control

General tips

Remove and destroy all infected parts of the plant including any foliage on the ground.

Plants growing in dry soil/compost conditions that are under stress will be more prone to infection. So, keep susceptible plants well watered and mulch the soil with bark or similar mulching material. Only water the soil, not the foliage as the disease spores need a layer of moisture on the leaves to grow.

Spray with a suitable fungicide

Spray ornamental plants thoroughly with a systemic fungicide. Continue spraying throughout the season as recommended on the label.

Watch the video: How to get rid of plants fungus. Rose plants fungus. Rose powdery mildew


  1. Dorrance

    It's completely useless.

  2. Hirsh


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