All roses are not equal
A few days ago, as I was doing my morning walk-about. I passed by the rose bush, Mary Rose. For the first time this season there was a black spot infection on the leaves.
I like roses. Once I had dozens of roses in the borders and there was a bed devoted to roses. The only selection criteria was the way they looked. Their need for attention and a busy work schedule was not a good combination.
Gradually tea roses disappeared from the garden. Then most of the floribundas followed the tea roses into oblivion. . Black spot is a rose destroyer I didn’t want to give up roses and I didn’t want to be tied to a schedule of preventative spraying. The solution seemed to be black spot-resistant roses.
There where roses that had survived for years in the borders. Gruss an Achen, a multiflora, and Alba Meidiland, a shrub rose had been in the garden longer than any other rose. I added a second Gruss an Achan and six Alba Meidiland to the borders. I was convinced there were roses tough enough to survive on their own. Bonica and Royal Bonica were added to the list of survivors. Scarlet Meidiland soon joined the others.
To my knowledge there are no roses that are 100-percent resistant to black spot. Some that resist the fungus at first later become susceptible. This may be caused by the fungus mutating, a new strain invading or a weakening of the plants immune system.
You can reduce the damage caused by black spot. All effective measures are preventative. Once an infection is established it cannot be cured. Remove the infected parts and destroy them.
Sanitation is the first defense. Clean up all infected leaves that fall from the plant. Burn them or bag and trash them. Do the same with all the canes that die.
Provide plenty of room for air movement around the bushes. Foliage that remains wet for extended periods is vulnerable to infection.
Water roses early in the day so plants are dry by nightfall.
Keep your roses healthy. Water them regularly during dry spells. Fertilize them during spring and early summer. Fertilizing in late summer and fall causes new growth that cannot harden before winter.
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