Sooty Mold

Asked August 9, 2016, 9:43 AM EDT

We have been dealing with black stuff all over our house, sidewalks, driveways, camper, deck, trees, shrubs, well, anything outside in our front yard. This started last year and it is really hard to get clean. I did an internet search and am wondering if this is sooty mold and if it is, how do you identify what type of insect is causing this, in fact, where do you even look for this insect? There are a lot of trees in our yard and both of our neighbors yards where all the leaves are covered in this black stuff.

Wright County Minnesota

1 Response

Hi,

It sounds like your trees have been attacked by sucking insects which produce a honeydew which in turn grows a sooty mold. Sooty mold is a fungus which grows on the honeydew. As the name implies, it is sooty in color and the honeydew can be produced so heavily that it drops from the leaves to objects below the trees, where the fungus can grow and look like pitch.

Control of the insects would be necessary to prevent sooty mold. Control of sooty mold is targeted at preventing or reducing insect populations. Scales and aphids are usually the culprits in sooty mold infestations. It's important to identify the species of insect present by checking your trees and see if you see aphids or scale. After finding which insect is doing the damage, you can then determine what control measures to apply and when. Check your trees and see if you see aphids or scale.

The following sites have more information on both aphids and scales:

http://www.na.fs.fed.us/spfo/pubs/howtos/ht_sooty/ht_sooty.htm

http://learningstore.uwex.edu/assets/pdfs/A3123.pdf

http://msue.anr.msu.edu/news/using_horticultural_oils_on_landscape_plants