That’s a rose bush?

Gardening is like a job. It’s something you really have to do every day.

If you do, you get big rewards. If you don’t you spend the rest of the summer playing catchup.

Some things are obvious. You know you have to pay attention to weeds if you ever want to find your plants. 21rose

But if you want to grow roses, they need to be on top of your list.

This photo should say it all. Yes, my hybrid tea got socked with  black spot – again.

Blackspot, “Diplocarpon rosae”, is a nasty fungus that manifests itself on rose bushes as black spots on leaves progressing to black spots fringed with yellow rings on both sides of the leaves. As they develop the spots enlarge. Eventually, as the disease spreads, the entire leaves will go from green to yellow and then drop to the ground. With time the entire rose bush may become defoliated. Leaves less than two weeks old are the most susceptible to this disease.

 

First the leaves get infected, then they all drop off.

To combat this, you need to do some prevention.

 While plants are dormant in spring, (too late for me) spray thoroughly with fungicidal soap or spray. Rose Magazine recommends chemical free wettable sulphur (both readily available at the local plant nursery). It definitely has a place in the chemical-free garden. Fungal spores cannot germinate in the sulphur film and thus cannot get a chance to attack the plant. To be effective the sulphur must be on the plant and leaves before the spores land on them. Sulphur washes off in rain and so must be reapplied repeatedly.

 

Here’s the tricky part. Remove all infected canes and get rid of them. Do not leave them on the ground. Do not compost them. These nasty spores can live forever.

Interesting to note. Right around the corner from my infected plant is a beautiful climbing white rose with no problems at all.

 

21tropicanaYes, it’s all about variety.  I used to think y0u had to forego hybrids if you wanted resistance to diseases. That’s not true.  The Ohio State Extension has a list of roses resistant to black spot.  Here’s one that’s definitely on my list. It’s an unusual orange one called Tropicana.  It sure doesn’t look anything like my rose bush.

 

There’s no question which one I’d rather have.

Tell me your favorites and your remedies for preventing black spot.  Send me an email at mgouger@poconorecord.com.

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