BlackSpot on Roses

Blackspot on roses is caused by a similar fungus to potato blight and thrives in similar conditions – warm, moist & stagnant air. You might well ask how so many roses are affected by it so! , but effected they will be unless you treat it by spraying regularly - every week. The fungus (Diplocarpon Rosae for those that must know!) will not kill your roses but will cause them to weaken by loss of their leaves and to flower poorly as a result.

There are several chemical sprays available but I prefer to use the homemade greener sprays listed below as an alternative. If you alternate your spray each week or two I think it always works better. When spraying chose a dry day and make sure you also spray underneath the leaves as well. If there is any blackspot on the leaves, remove these leaves plus any fallen leaves and burn them, rather than composing them.

You could start spraying now as the leaves are starting to show and get in ahead of the fungus, and continue every two to three weeks until the weather warms up and then increase to every week.

Baking Soda Fungicide:

1 tablespoon of baking soda/potassium bicarbonate

1 tablespoon of either horticultural oil/molasses/citrus oil

1 gallon/4.5 litres water

Vinegar Fungicide:

3 tablespoons of cider vinegar

1 tablespoon of either horticultural oil/molasses/citrus oil

1 gallon/4.5 litres water

As always happy gardening!