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Black Spot on Roses - Treatment and Prevention

By Edited May 15, 2015 1 2

Many homeowners and gardeners plant black-rose bushes to set the garden awash with color. Roses come in a wide array of bright and vibrant colors all of the way to gorgeous pastels. Some black-roses have very little or no scent, while some are highly fragrant. Some rose bushes produce a few large blooms at a time and some will produce tons of tiny flowers. Choosing colors, sizes, fragrances and types of black-rose bushes is all a matter of choice for the gardener. Caring for and maintaining a rose garden can present a few problems and issues aside from the obvious – being poked with thorns – such as black-spot.

black-spot is a type of fungus named Diplocarpon rosae. As the name suggests black-spot causes the black-rose bushes to develop black-spots on the leaves. Affected rose bushes will develop the tell tale black-spots on the leaves that progress to yellow rings around the black-spots. Eventually, as the black-spot progresses, the entire leaf will turn yellow and fall off. Within days or weeks of black-spot’s first appearance, the rose bush will have lost all of its leaves.

How Does black-spot Spread and How to Control it?

black-spot is a fungus that spreads from black-rose bush to rose bush through water. The spores travel in water droplet, rain drops and can become airborne if the humidity is very high. Typically, whatever remedy you choose to prevent black-spot gets washed away after a rainfall or after regular watering. If you water your roses from the base of the plant it will not only help to slow or stop the spread of black-spot, but will also save you from having to reapply the treatment to the roses.

A great part of controlling black-spot is to create a hostile environment that the fungus cannot live. There are many remedies available to treat and prevent black-spot, some of which are commercially available and some can be made from household ingredients.  If you choose to use a commercially available preparation be sure it is specifically intended to treat black-spot.

When black-spot First Appears on Your Roses

Trim the affected leaves away and dispose of them. Do not put the leaves in a compost pile because you will foster the growth of black-spot and contaminate your compost pile.

After trimming away infected leaves, always wash your trimmers and other gardening tools that came in contact with the black-spot in an antibacterial soap and hot water.

Wash gardening gloves in antibacterial soap and hot water.

black-spot can and will spread quickly. The fungal spores will attach themselves to tools, gloves and clothing, making you the carrier.

Highly Effective Treatments

Bayer All in One black-rose and Flower Care Concentrate is a multi purpose spray for roses. Bayer spray not only is effective against black-spot, but also helps to kill and control black-rose rust, powdery mildew and southern blight. Bayer is also an insecticide that deters a variety of pests including Japanese beetles and caterpillars. While working as both an effective fungicide and insecticide it is also a fertilizer that boosts root growth and big, beautiful buds and blooms. Comes as a granular preparation that requires dilution in water. The spray is applied via pump sprayer or spray bottle.

Ortho  Rose Pride Rose & Shrub Disease Control is endorsed and approved by the American Rose =-Society for its effectiveness against harmful fungi. Ortho black-rose Pride not only fights black-spot, Powdery Mildew and Rust, it helps to prevent it from infecting your roses in the first place. Ortho is used as both a preventative treatment and works well to kill fungi. Ortho comes as a concentrated liquid that is diluted with water and applied to the roses.

Homemade Treatment

Add 1 gallon of distilled water to a bucket and stir in the following ingredients: 2 tablespoons of baking soda, 1 1 /2 tablespoons of summer weight horticultural oil and 2 tablespoons of liquid dish washing soap. If you have a large rose garden, you can double or even triple the amounts to make enough to spray all of the roses and prevent all of your roses from getting black-spot. If you have only one to two rose bushes cut the ingredient amounts in half.

If you have a large rose garden, pour the black-spot treatment into a pump sprayer and spray the rose bushes with a light coating, begin at the top and work your way down. Make sure you spray the undersides of the rose leaves. Walk around the entire rose bush to ensure you coat it completely with the treatment. If you have a few rose bushes or don’t own a pump sprayer, pour the mixture into a spray bottle and spray the rose bushes.

Tips for Treating black-spot

Treat the rose bushes every other day with the black-spot remedy until the roses have had no sign of black-spot for at least two weeks. During the treatment time, only water the roses from the base of the plant. If it should rain, wait for the rain water to dry and spray the treatment onto the rose bushes.

 Use all of the spray when you treat the black-spot. The spray cannot be store because it will lose its effect.

 Only treat the roses in the early morning. If you treat the roses during the day, when the sun is hot you will burn the leaves. If you spray them late afternoon or early evening the spray will not dry properly and will not work.

Spray the Soil surrounding the roses because the black-spot fungus will live in the soil and cause a second wave of black-spot.

Keep your garden clear of dead leaves and debris because they can also harbor the fungus.

If the Homemade Spray Does Not Work

If the homemade black-spot treatment is ineffective – you will have to use a commercially available treatment or run the risk of losing your rose bushes.

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Comments

Apr 10, 2012 1:08pm
Deborah-Diane
We have several rose plants in our courtyard, and I have found these products to be very helpful in caring for them. Thanks for the helpful article!
Apr 10, 2012 1:13pm
Jack_Luca
Yes, they really do work. Good luck with your roses.
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