Mildew on roses … also frequently referred to as ‘roses powdery mildew is a fungal disease caused by Podosphaera annosa. The signs that this problem is having an impact on your roses are obvious.
The signs of mildew
Mildew on roses results in a very obvious white growth affecting leaves, flowers and stems. This type of mildew can also show up as yellow, reddish or purple discolouration on leaves. This type of mildew can also show up as yellow, reddish or purple discolouration on leaves.
Young leaves can also be distorted or curled and if the mildew can also affect buds and prevent them from fully opening.
High humidity and dry soil can encourage the growth and spread of mildew on roses.
There are a number of things you can do to prevent mildew from forming on your roses. Planting your roses in full sun and in places with good air circulation is perhaps the most important thing you can do.
Don’t plant your roses in areas where they are sheltered or where there is little air circulation and don’t plant them close together. If you allow plenty of room for the air to circulate between them you will reduce the humidity level between the plants and that makes it much harder for the fungus to take hold.
Plant your roses in well-drained soil but keep the water up to them and don’t be afraid to add mulch to the garden around your roses.
Watering your roses while holding the hose nozzle over the top of the roses can help the fungus and mildew to grow. It’s best to water your roses around the base of the plant and try and avoid getting water on the leaves because that can encourage the growth of the mildew.
Treating infected plants
Remove affected shoots as soon as the mildew begins to appear.
At pruning time prune the bush is such a way that the bush is opened up and air can circulate through it.
There are a number of chemicals you can use to control mildew on roses and your local nursery will know what works best for your local climate. They will also be able to advise you on how many applications you will need to make to get the best results.