Question
I live in North Carolina, she sandhills region.  I want to know what the best way to get rid of Blackspot on roses is.  I have about 10 roses in a bed of compost.  They do really well except for the fact that they have Blackspot.  I have heard that you must prune the leaves with the spots, and that you must rinse the pruning shears after every plant to keep the desease from spreading from plant to plant.  I was also told that you must keep the leaves picked up from the ground when they happen to fall off.  This is all very hard work, and I want to know the absolute best way to get rid of it, and prevent it from coming back.  Please help me, my roses are too beautiful and are doing too well to allow this disease to keep spreading.  This is their second year with the disease.

Thanks,

Jessica Stewart

Answer
Well first of all, you don't have to cut the leaves off that have spots on them, you don't have to clean the shears off either and you don't have to constantly pick up the fallen leaves with black spot on them.
The spores of black spot float around in the air and when it rains or is windy, they are forced to the ground. If they land on soil or fallen leaves, they soon die but if they land on a rose leaf then they start their life cycle by pushing their roots below the surface of the leaf. When they have killed that part of the leaf that is when you see a black spot. Too many spots on the leaves will kill the whole leaf. Good success has been attained by using a dormant oil spray in the spring before the roses leaf out. Then you kill the spores that have over wintered on the canes. The weather does have something to do with this disease as fungus like damp and humid condition to grow well.There are also certain colours which are far more prone to black spot than others, such as scarlet reds, apricots and yellow.  You can also start to spray with any rose fungicide just as the roses are starting to leaf out then you kill the spores that have over wintered on the canes. Spray weekly for a month and then just once a month and you will see a big difference in your roses. Spraying on leaves that already have black spots on them is useless The way current fungicides do help is by preventing new infections. The goal is to have new growth coated with the material before any attack, so that when a spore lands, it lands in a pile of fungicide, rather than on a clean and vulnerable leaf surface. So you can see that you can't get rid of this disease permenantly, you can only just keep it under control. Hope this helps. Lynnette