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Protect your roses from Blackspot |
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Diplocarpon rosae is the name of the fungus which causes the rose disease Blackspot. You must start taking corrective action as soon as you notice any sign or symptom which shows that your rose bush is being infected with Blackspot. If you don’t do this, your rose bush may not survive the winter cold and will produce lesser number of blooms.
You can not detect Blackspot in the initial phase. But later, the signs become visible. In fact, by the time the signs are noticeable, a good 3 to 10 days could have elapsed since the bush got infected. You notice black colored spots on the leaves. With the advancement of the infection, a yellow ring appears around the blackspot and it gradually spreads on the underside of the leaves. If you watch closely, you can see the spore-producing spots. These blackspots keep on growing till the leaves turn completely yellow and fall off.
Since blackspot is a kind of fungus infection, it spreads from one bush to another, if you leave it untreated. It can survive the bitter cold, while living on the fallen leaves. It also affects the cane of the rose bush. The harsh winter can not kill the fungus.
Like all fungal infections, the bacteria grows in warm, humid climates. Germination of the spores take place 7 hours after being in moist environment and the right temperature for this is between 65 F (18C) and 75F (24C). the disease spreads rapidly as the temperature gets higher and climate becomes warmer.
Taking proper care and corrective action is the only way you can prevent the disease from developing and spreading. You must clean your garden during the fall season, and clear all fallen or dead leaves and infected canes as spores find it very convenient to thrive on them. During spring, while your roses are still dormant, get some soluble sulphur and fungicidal soap. Spray your rose bushes thoroughly with this mixture. The sulphur covers the leaves and spores can not stick to the sulphur. Since the sulphur coating may get washed away in the rain, spray your rose bushes as often as you think fit.
Remember, any fungus needs a damp and wet environment for germination. So always keep the leaves dry and moisture-free. For instance, plant roses in a place where it gets maximum morning sun, so that the morning dew can rapidly evaporate. When watering, use sprinklers, and water only the roots but not the leaves. Choose early morning as your watering time, since then the plants get plenty of time to get dry. Keep the bushes well pruned so that there is plenty of fresh air circulation between the leaves. Likewise, keep a lot of empty space between the bushes.
The moment you spot the early symptoms of blackspot, cut off all the affected parts and throw them in the trash bin. Do not use the compost pile for this, as fungus thrive on dead leaves. Then spray adequate quantities of sulphur on all the leaves.
All that a rose bush needs is the right kind of care, attention and intervention at the right time. If you can ensure this, your roses will produce glorious blooms for many years to come.
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