Roses and Black Spot

Caring for roses

One of the many diseases that attacks a large quantity of roses is blackspot. This infectious disease is caused by the fungus Diplocarpon rosae. When your rose bushes start to exhibit the symptoms of Black spot, you should take immediate action. If you do not, your plant will begin to produce less blooms. Another reason is that the plant might not have the strength to survive thru the winter.

Although black spot may be easy to distinguish in its more developed stages, it is sometimes hard to identify in the beginning. In fact, once the symptoms of black spot do become evident, it’s between 3 and 10 days after the fungus first developed. The first visible signs are usually black-colored spots that cover the leaves. As this fungus grows, these black spots start to grow a yellow ring around them and the spots develop through to the bottom of the leaves. When you look closely at the leaves, you will see spots that are able to produce spores.  As these black spots keep on to develop the, entire leaf may turn yellow. Once the leaves have turned yellowed, they will begin dropping off the bush.

Since it’s a fungus, black spot is easily spread. It will move from one plant to another if it is not treated. The fungus can endure the winter on leaves that have fallen to the ground. It is also able to live on the cane after the plant has been contaminated. This being the case, you cannot expect the harsher weather to kill it.

Living as a fungus, blackspot can flourish in warm, damp surroundings. When the spores get wet, they’ll germinate within 7 hours provided the ambient temperature is between 65 F (18 C) and 75 F (24 C). The disease can spread faster in warmer weather.

One of the best ways to keep this disease from germinating or dispersing amongst your rose plants is via correct care and feeding. The three steps that should be taken give you a better chance fo stoppng spread is to:

1. Rake up all dead leaves from around your plants
2. Cut away any infected canes on the plants.
3. Remove all of this refuse from the proximity of your plants.

This will help you reduce the chance that the spores will survive.

While roses are still inactive and before they begin their spring development, visit your local nursery and buy wettable sulfur and a fungicide soap. Apply these materials by spraying all your rose bushes soundly. As the spores can’t adhere to the sulfur, the leaves you treat are protected. Because rainfall will rinse the sulfur off, it is a very good practice to reapply on a regular basis.

One condition that helps the fungus germinate is a wet environs. A way of reducing infection is to make sure that the leaves are kept moisture-free. One way to achieve this is to place your bushes in sunny locations well drained. If they’re planted in shady spots, the morning dew won’t evaporate and this will furnish a fine spot for the fungus to develop. Another thing you can do is to use a soaker hose when watering. This will allow the roots to get watered but not the leaves. Also, by watering early in the day, you will provide lots of time for the water to evaporate. To sustain good air flow, prune the bushes on a regular basis. An additional way to allow for this is to provide plenty of distance between the bushes.

By checking your roses on a regular basis, you will be able to see first signs of Black spot. This will allow you to cut away affected parts and throw the clippings in the trash. The clippings do not get put in the compost pile ( the fungus will stay alive on the leaves). This will be a good time for spraying the leaves with sulfur.

The best way to help your roses to produce beautiful flowers year in and year out, is to give them a little bit of tender loving care.

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Tagged as: blackspot, caring for roses, dead leaves, rose bushes, rose plants