Ouch!
Horticulture Hotline 12/04/23
By Bill Lamson-Scribner
Last week, I wrote about the explosion of Large Patch, Brown Patch, and Zoysia Patch. Over Thanksgiving weekend, the conditions were perfect for the disease triangle, and the disease flourished! If you missed the article and want to read it, you can go to possumsupply.com and look under the Horticulture Hotline tab.
The extended warm weather we have had has kept an insect that attacks our beloved Sweetgrass active as well. Sweetgrass is being attacked by an unarmored, soft body, scale insect called a mealybug. Mealybugs are like aphids, scale, white flies, the “nasty rascal, the chinch bug,” lace bugs, and other sucking bugs in that they suck plant juices or sap from the host plant.
I was surprised when I first saw mealybugs on Sweetgrass. I usually associate mealybugs with plants grown inside buildings, homes (interior plantscapes) or greenhouses. I usually think of ornamental grasses as being pest free – wrong!
As with any sucking bug, you want to get the situation under control fast, or you will have the secondary problem that looks way worse than the fuzzy, airy mealybugs. The secondary problem is the dreaded sooty mold.
Sooty mold is the black mold that grows on the excrement (poop) of certain sucking bugs. Have you ever seen a black gardenia (from white fly poop) or crepe myrtle (from aphid poop)? Certain insects have a very short digestive track and they are drinking sap from a plant that is pressurized. The sap goes in their mouth and out their behind very rapidly covering the plant with a sugary substance (often called honey dew) that this mold grows.
In human terms, if you could connect your mouth to, let us say, a keg of beer or maybe a soft serve ice cream machine at some point the beer or ice cream would be coming out of somewhere (nose, ears, …) leaving a mess. Insects have hardly any digestive tract to slow things down, so the sugary plant juices come out of their butt. On this substrate grows the unattractive black sooty mold.
A very effective way to control these mealybugs, while not hurting the beneficial insects, is to use an insecticidal soap. Also drench the area around the Sweetgrass with Dominion.
Dominion is a long-term systemic insecticide that will give you more time to do something else.
Check your local temperatures to see if it is a good time to apply Neem Oil or Horticulture oil for over wintering insects. Armored scale (like you see on camellias – aka tea scale), unarmored scale (mealybugs, cottony cushion scale), aphids, and others.
Always read, understand, and follow product label. The product label is a Federal Law.
