Weird pattern generated from Black Spot fungus?

I had given up on roses since my failure to keep a rose alive and disease free about a year ago.  What I later decided was that the garden centers in San Jose sell roses that are inappropriate for San Jose’s weather conditions.  My conclusion stemmed from the fact that at the end of the gardening season (late fall) the roses that remained in the stores had all this powdery mildew and brown leaves.  So this observation led me to decide, never again would I purchase a rose!

In December of 2011, I discovered Rosa Californica, the California Rose.  I had to add this rose to my native California plant collection and give roses another go.  I made sure to place it in the sunniest spot in my patio so as to create the best conditions for it to thrive in.  I have carefully built my garden specifically to attract beneficial insects to dine on the aphids would surface.  Sadly today I found many aphids (green, black, and purple) on my rose.  I also found that my plant has the Black Spot fungus.  This is a symptom of the plant being in humid/wet weather for too long.  Well it has been rainy and very humid.  But as a native plant, this rose has really disappointed me so far.  I mean, there’s no one spraying fungicides on California roses out in the wild!  What the heck!

Rose leaves with Black Spot fungus

Browning leaves caused by Black Spot fungus

According to http://www.RoseMagazine.com, “the fungus becomes active in a wet environment with a temperature of about 24 degrees Celsius (approximately 75 degrees Fahrenheit). It needs about 7 hours of these conditions to germinate and then symptoms will begin to appear on rose foliage within three to ten days. From then on spores are produced every three weeks. If unchecked, black spot can affect the entire rose garden leaving an unattractive appearance of many ‘bare-naked’ plants. Spores can over winter in the garden so autumn cleanup is crucial otherwise the entire cycle can repeat itself the following spring and summer.”

Black Spot fungus...a quite representative image

For the treatment Rose Magazine offers a solution:

” The worst case scenario can be avoided with some preventative measures, a keen eye and diligence. While plants are dormant in spring, spray thoroughly with fungicidal soap and wettable sulphur (both readily available at the local plant nursery). Sulphur is actually a historical remedy used for hundreds of years by farmers for their crops. 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. The product is sold in powder or liquid form and also works well against mildew and rust. Other preventative measures include keeping the leaves dry when watering (try soaker hoses or drip irrigation methods), water in the morning so that foliage has a chance to dry off throughout the day and pruning plants to improve air circulation.”

Greaaaat!  Where am I going to find Sulphur?!  I think for now, I’m just going to relocate the rose to the middle of the garden, and clip off the diseased leaves.  Then I’m going to have to coyly ask Henrik for my Fungicide back and I’m sure he’ll make fun of me since I sort of bashed his dudleya kind of recently…

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