What is the black stuff on my nasturtiums?

15 years ago

I have grown nasturtiums for about 3 seasons now, and this is the first time I encountered the black small specks coming on the leaves, seeds, stems. It is thick in places, and just separate black tiny (like small seeds) things in other places. It is very sticky if I get it on my fingers.

Is it from all the rain we had this summer? I'm growing these in z5b Massachusetts. What could it be and how do I

get rid of it? I hope it is not insect eggs, because all my plants will end up devoured when they hatch.

I haven't taken a photo of it, but if necessary I could do that. Any help or ideas will be appreciated.

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Comments (8)

pfhlad0
15 years ago
I also have tiny black "seeds" all around my vinca annuals (in pots). I have two on the front porch and two on the back and all have these little seed-looking things on the ground around them. I hope they're not rodent droppings.
tapla (mid-Michigan, USDA z5b-6a)
15 years ago
... probably sooty mold growing on honeydew from scale/aphids.

Al
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User
Original Author
15 years ago
I'll take my magnifying glass out to see if any aphids are there with the black stuff. It is GROSS!

I haven't seen anything crawling but I was focused on the black stuff and may have missed anything green.

I'm taking a photo in the morning and posting it here.
Thanks for your comments. I don't want anything bad happening to my beloved nasturtiums.

If it is sooty mold, do you spray for aphids, something like Sevin Dust? or what? This is extensive and spreading more every day.
User
Original Author
15 years ago
Here is the clearest picture I took today. The wind was blowing so the others did not turn out clear.

How do I get RID of this stuff?!!!!
{{gwi:24296}}
calliope
15 years ago
looking at the stems, they appear to be aphids
tapla (mid-Michigan, USDA z5b-6a)
15 years ago
I think so, too - and the black deposits are almost undoubtedly sooty mold growing on their excreta (honeydew). To tell you the truth, and given the time of year, I don't think the plants are worth the effort of trying to save them, but if you are intent on snatching the plants back from the brink - I would use something a little less harsh than Sevin. A sharp stream of water will dislodge them. Safer's Insecticidal Soap (or equal) is a good remedy for aphids, and cold-pressed neem oil in a 50/50 mix of rubbing alcohol/warm water will provide good knockdown and will sterilize the existing population.

Al
shapiro
15 years ago
I have heard of people growing nasturtiums on purpose to divert aphids away from other plants. We love to eat nasties in our salads. Whenever we get an aphid infestation, which happens maybe once in five years here, we just get rid of them with a brisk jet of water from a hose.
rhizo_1 (North AL) zone 7
15 years ago
Nice crop of black aphids, commonly called 'black bean aphids'. They are very attracted to nasturtiums, amongst a wide variety of other plants (annuals, perennials, shrubs, trees, grasses!)

The 'sticky' is caused by their excrement (called honey-dew), a by-product of all that sugary plant sap they ingest, as I mentioned in my email. Sometimes, a black mold will grow on that honey dew, but I don't see any sign of that in your pictures.