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Dealing With Black Spot Disease on Roses...

Be on the look out for Black Spots on Roses - Blackspot disease is a common and serious fungal disease affecting rose plants.

Written by Cheryl Lewis. © 2004 Electronic Perceptions

Rose gardens can be a center of your landscape, or you can spread roses through out the various positions in your landscape. No matter how hard you try, disease and problems can occur while growing roses. Black spot is a disease that you will notice right away. Black spot is common on hybrid roses.

Some gardeners feel that black spot is how roses ‘look’ when mature because this problem is such a common one. If you really want to grow roses that will not have black spot, you will need to find roses for your garden that are not hybrids.

Black spot is really a fungus growing in spots measuring from small dots to larger circles that measure about half an inch. Before you see the actual black color of the fungus, the spots, dots, and circles will appear a yellow color.

Around the outer edges of the spots and dots, you will see little portions of the fungus actually lifting off the leaf. Sometimes the lifting of the fungus is so small that you need a good magnifier to notice this. You cannot get the fungus off the leaf without destroying the leaf.

As this fungus attacks more leaves covering your rose bush, the rose bush will start to lose its leaves. Using some chemicals can hold the fungus at bay or prolong the life of your rose, but in the end, the fungus will win. The fungus becomes resistant to the chemicals and stronger killing off the leaves.

What will you do if you see the beginning of black spot in your rose garden?
If you find black spot starting in your rose garden, you need to act quickly and clean up your garden. Pick off all the leaves that have yellow spots and the starting of yellow staining.

Dispose of leaves in the dump or by burning them. Do not put these leaves in your composting pile. This fungus will survive the coldest of winters. If you have a plant that is heavily infected you will have to dispose of it so it cannot continue to breed.

To protect your plants further, in the fall months, cut your roses back to about six inches out of the ground. The fungus will live in the branches, the canes, of the rose bush over the winter months. Disposing of the plant will keep the fungus from surviving the winter months.

Using dormant oil and a sulfur spray to coat what is left of your rose bushes, you can protect your roses during the winter months from infections from the black fungus again. Mulching around the rose bush and piling the mulch up around the rose branches that you have cut back will prevent the fungus from breeding and surviving.

In the spring, be sure to sprinkle a lime and sulfur mixture through out your rose gardens. This prevents the black fungus from starting and killing it while it is in the very early stages in case you missed any. After each rain, you will need to sprinkle this mixture around your roses again.
 

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