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Perennials/Black mold on firebush



second pci
second pci  
I live in Fl. and just recently did a severe pruning on this firebush shrub.  It is just starting to grow back and I am noticing a lot of what looks like black mold.
Can you tell me what it is and how to kill it?

Hello again Mary. I am happy to help with this issue.

The black specks that you are seeing have nothing to do with your pruning, so please do not feel that you did anything to harm your plants.  The black mold you are seeing is in fact mold. It is sooty mold and it is typically caused by the secretions of aphids, which are particularly common as temperatures warm up and the little devils awaken from their winter slumber. I see it every spring on roses that I have overwintered in my garage. Your creatures are gone or you would have noticed hundreds of little crawling creatures on your plants. What you are seeing is the evidence of their presence.

The important things to understand about aphids (also fondly referred to as "plant lice") is that they are essentially born pregnant and can reproduce by the thousands in a matter of days. They excrete the substance that you are seeing, and then it turns black. It's not fatal.

The first step is to give the plants a thorough washing with a nice sharp spray of water. In fact, this is also the cure. You can use insecticidal soap, an organic and inexpensive remedy found in an immediate use spray or concentrated form in hardware stores and garden centers, but you can also alleviate the problem by simply spraying the plants - the insecticidal soap is not actually necessary. Aphids cannot fly - they crawl. The sharp spray of water knocks them to the ground where they become food for birds.

So both cure and prevention are the same. Go out every day with your hose and use a setting on your spray nozzle that is probably labeled "sharp spray". Make sure that you hit all surfaces, especially the underside of the leaves where they hide.

If you watch for their arrival early each year, you can prevent this problem by spraying every day as a matter of course.Their season is short, and you can stop spraying after a few days if they do not reappear.

Have I explained well enough? If you have any concerns or questions or need more clarification please feel free to write again.




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Donna Mack


I am a Master Gardener through the University of Illinois Extension.I can answer questions about pest control, especially voles, rabbits, chipmunks and slugs, and have done so on Dave's Garden Watchdog under the name DonnaMack since 2002. I have a lot of expertise with ornamental grass, hardy roses and old garden roses, minor bulbs such as ornigothalem, chionodoxa and allium as well as most types of lilies. I am knowledgeable about organic methods and I grow perennials, annuals and vegetables from seed.


I have been gardening since 1998 and have raised roses, peonies, annuals and perennials (the latter two from seed), and numerous shrubs and trees, many of which I have planted. I am familiar with many organic techniques and use as many as I can but know the chemical solutions, which are most benign and how to use them. I LOVE gardening, and I get great satisfaction with helping others so that they reach the state of joy that gardening can bring to those inclined to it.

The American Lily Society

I have numerous entries in Garden Watchdog under the name DonnaMack. I write three to four columns a year for the Kane County Chronicle.

I successfully completed the University of Illinois Master Gardening Program in March of 2013. I did this to augment extensive self study through books (I've probably read 100) and an arts degree, which helps with aesthetics. I am purely an amateur, but one who studies, reads, and documents extensively. My gardening log began in 2000, and has hundreds of entries, so that I can use my successes and failures to assist other gardeners.

Awards and Honors
The University of Illinois created a Team with Work Award for master gardeners who work together to create what they regard as an outstanding project. I won this award as part of a group that created "The Idea Garden", which suggests plants for home growers to attempt to grow. My personal contribution was salvias - ornamental and culinary hardy and tender perennials, which I grew from seed and tended through the season.

Past/Present Clients
I am currently overseeing and performing the maintenance of two large English style gardens in a suburb of Chicago, and recently acquired the management and redesign of a large estate garden(2015.)

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