Question
I live in the north-east corner of Maryland, just south of the Pa state line. My black-eyed susans are coming in very nicely, big and healthy looking.

The underside of all the leaves are hundreds of small black
looking bugs (aphids). Is this a real problem, and what can I do.

Please Help,

Dino

Answer
Dino, Few growing garden plants have the good luck needed to escape the Attack of the Aphids you are experiencing with your flowers.

Aphids come in different colors and shapes, but they are all soft-bodied insects designed to suck the life out of plant parts.  They appear out of nowhere and suddenly overpopulate your garden.  Can I assume these are round black Aphids that have formed a dense groups under the leaves of your Sunflowers that barely seem to move when disturbed?  If they run for cover, it's a safe bet these are something other than aphids.

I am not sure what plant you are growing.  Is your Black-Eyed Susan the Rudbeckia shown at these links: www.bio.brandeis.edu/fieldbio/Wildflowers_Kimonis_Kramer/PAGES/BLACK-EYEDSUSAN_PAGE_FINAL.html or www.daytonnursery.com/encyclopedia/perennials/Rudbeckia.htm?  

In some parts of the country, a Black-Eyed Susan also refers to the Sunflower, which is an annual that comes in many varieties.  Presumably you are growing Rudbeckias.  Is that right?  

Most experts recommend that aphids be knocked out of commission with a blast of water under the leaves.  This to me does not always sound very practical -- I have tried it with roses, and although Rudbeckia does not have the thorns of a rose, turning every leaf and bud on every plant without missing a beat is not what I call an effective plan of attack.  

The University of Minnesota Extension Service has this to say about Rudbeckia aphids:

"Large aphid numbers cause discoloration of flower petals and leaves and result in general wilting. If you wish to control them, consider applying insecticidal soap to reduce aphid populations. This product is effective against aphids but has little effect on natural enemies, like ladybird beetles. However, this isn't necessary as even a severe infestation is not likely to kill the plant."

Hundreds of aphids would disturb any gardener, Dino, so I would not sleep at night despite what they say about aphids being "not likely to kill the plant".  You don't really want a plant that just survives, anyway; you want it to bloom, all summer, beautiful healthy flowers.  Right?

So march yourself over to Gardens Alive (www.gardensalive.com) and order a package of Stay-At-Home Lady Beetles or whatever they're calling them these days.  

I once had an awful case of scale (little black nonmoving dots under the leaves) on my indoor 15-year-old ficus plant.  For years, I tried removing things leaf by leaf.  They persisted.  Until one day I bought a house, moved the ficus outside, and unleashed Lady Beetles at the base and on the leaves.  The next day there was no sign of Scale Life on that Ficus.  They never, ever returned.  Ficus lasted until the pipes burst one frigid winter and all signs of life in the den ceased.  Orchids, ficus, orange trees, everything was lost.  

But I digress.

That is my best advice.  If I misunderstood your description of Black-Eyed Susan or Aphids, Dino, please let me know and we can re-consider your problem.  But I do believe this will work for you.  

Love those Black-Eyed Susans!