Episode: #10 4/11/06
Presenter: Judy Horton

It is no wonder that roses are such favourites as their flowers are breathtakingly beautiful. Ask any rose grower about their number one problem though and they are sure to mention black spot.

Take a look at the leaves and you will see where the name comes from. The disease starts off with small black circles on the leaves. Once the leaf is infected it ages much faster than it should. The whole leaf gradually turns yellow and then eventually it drops off the twig.

Now that is a problem for two reasons. First of all, every leaf that falls makes the plant weaker because leaves are a plant?s food factory, so the rose starts to get weak and hungry. As well, the disease spores that stay on the leaf while it is on the ground can then be splashed back up or fly upwards to attack more leaves.

So straight away you can see that one of the most important things you can do is to get rid of all the affected leaves. Because the disease can stay in the stems as well, when you are cutting roses it is a good idea to wipe your secateurs with disinfectant after each cut.

The spores can only infect a leaf if it stays moist for at least seven hours. So that gives you another clue to controlling your black spot problem. Keep the leaves dry.

You can do this by watering at the base of the plant, never over the leaves, and by watering in the morning so the leaves dry as quickly as possible. Of course, if you live in a dry climate, you will be ahead to start with.

The other thing you can do to control this horrible disease is to spray rose bushes regularly with Yates Rose Gun, which contains a very effective fungicide and has the bonus of controlling insect pests as well.

No matter how hard you try you will probably still get some black spot in late summer but by following these hints you will keep it at a minimum.

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