It’s the scourge every rose grower faces: black spots. The nasty fungal disease sees rose leaves develop dark, irregular spots that turn yellow and fall off. If left unchecked, it can kill your perfect rose bush so let’s see what can be done to treat and prevent those black spots to ensure you always have beautiful roses in the garden.
How to prevent black spots
The fungal disease thrives in warm, humid climates so make sure when planting place roses in breezy and sunny spots. Space bushes apart and limit other plants crowding around them. In particularly humid spells open up your rose bush to create air movement through the middle to minimise the risk of humidity. Avoid watering foliage, especially later in the day; instead water around the roots of the rose. Remove leaf litter and prune diseased canes back to healthy wood. Remember an ounce of prevention is worth a pound of cure so be vigilant in feeding, spraying and pruning your rose bushes.
How to treat black spots
Once your rose bush is attacked by black spots unfortunately the markings are there to stay until the spotted leaf drops. However, the fungus can still be killed so no further damage will be done to your rose bush. Remove diseased part from your bushes and clean up fallen spotted leaves. Do not use the leaves for compost, throw them in the bin so not to further infect your plants. Now you need to apply a preventative formula to minimise further attack. Use black spot fungicides to keep the spots at bay and increase disease resistance. A quarterly dose of sulphate of potash will help roses as well by thickening the cell wall. Also ensure roses are well fed with an organic rose fertiliser every six to eight weeks during the growing season as the better fed they are, the better they will be to resist disease.
Spraying diseased leafs with fungicide and feeding plants will help your roses but some bushes might still be beyond treatment. At these times the only things to do is remove the bush so they don’t infect any other rose bushes.
This article was written in partnership with Over60.