Rose Black Spot – Diplocarpon Rosae
Have you been noticing small spots on the leaves of your favorite roses?
It’s officially known as Diplocarpon Rosae, but more commonly Rose Black Spot or just Black Spot. This is one of the most common issues that we will see when tending to roses, although, it can also show up on many other plants as well.
First, they will just appear as a few small black spots on the tops of some of the leaves. But over time, they will increase both in size and quantity. Usually they will first show up towards the bottom of the plant, and then it will work it’s way up. But it’s also worth noting that they really can start anywhere on the plant. It really just depends on the specific conditions that they are living in.
Leaves are the most vulnerable when they are wet for five to six hours or longer depending on the climate, time of year, and geographical location. Black spot also likes to show up after those longer periods of wet weather. The most severe infections will actually cause the leaves to turn yellow and die.
Rose Black Spot will spore during the winter months in the fallen leaves on the ground. This is why it is so important to keep the base of the plant free of dead leaves, branches, and other plant matter.
A Few Tips
Make sure to plant your roses in a quality soil with good drainage.
Keep the ground around the base of the plant clean and free of any fallen leaves or debris.
Throw all infected leaves into the garbage and not into the compost bin. Yes it matters!
Disinfect your clippers or pruners after each use, especially after dealing with infected plants. This is going to help prevent the spread of any diseases that you come in contact with. There could easily be a problem on an existing plant that you aren’t even aware of so it makes it that much more important to keep your tools clean.
Water just the base of the plant, not the leaves. This is petty self explanatory here. Keep that water at just the base of the plant. Water around the stem and the soil, but try not to splash onto the leaves, stems, or branches.
Feed with a quality rose fertilizer consistently
Read the manufacturers instructions on exactly how much fertilizer to give to your roses and how often you need to give it to them. This will slightly vary from one brand to another and you do not want to overfeed. You will severely damage the plant if you overfeed and could possibly kill them so it’s always better to error on the side of caution and give them a little less when you are starting out or trying a new brand of fertilizer.