Garden Q&A: Controlling mealy bugs and testing the soil
By Ellen Nibali
Jan 09, 2020 | 7:00 AM
I have a gardenia that I keep indoors during cold weather. For a long time it has not bloomed and I see a white powder where it is supposed to form buds.
Inside that waxy fluff are mealybugs. They are tough to control and if you have valuable plants near the gardenia, the mealybugs can move to them. It’s usually easier to simply toss inexpensive plants than try to eliminate the mealybugs. This is because their eggs are enmeshed in waxy fluff and thus relatively water proof. Likewise adults and nymphs can be covered in wax and obscured in plant nooks and crannies where it is difficult to get thorough pesticide coverage.
For this reason systemic insecticides may offer the most reliable control because they make the plant toxic to feed on rather than relying on a contact insecticide. If a contact insecticide is used be prepared to repeat the applications two or more times to kill nymphs that hatch from protected eggs and adults or nymphs hiding in plant tissue. If an infestation is discovered early enough on a few cherished house plants, the mealybugs may be removed by a cotton swab dipped in alcohol or fingernail polish remover. Keep an eye on the plants for a few weeks to make sure no mealybugs are overlooked.
Putting houseplants outside over the summer where predatory insects can attack a pest insect on your plant sometimes provides the best pest control.
Gardenia’s can be finicky bloomers, and insect infestation lowers the plants’ vigor, but there are many reasons why they don’t bloom. Bud drop is the most frequent complaint. Some contributing factors are: lack of uniform or adequate soil moisture, low humidity, too warm or too cold, insufficient light and rapid temperature fluctuations. The last can result from bringing a plant in from cool outdoors to hot indoors. Search “mealybugs – houseplants” on the Home and Garden Information Centerwebsite.
How do I determine what type of soil I have in my new garden?
The three major mineral soil classes are: sand, silt, and clay. They are based on particle size. Imagine the relative sizes being comparable to a basketball, a golf ball and the head of a pin respectively. Soil type —known as “texture” — is determined mostly by the relative percentages of sand, silt and clay. For example, a “silty clay loam” will have more silt and clay than sand.
You can determine the type using your fingers. When you rub soil between your fingers, the sand feels gritty, the silt feels like flour or talcum powder, and the clay feels sticky or greasy when wet.
All soils can be productive. To improve them, add organic matter on a regular basis. A soil test will tell you nutrient levels in your soils, not soil type. However, some soil test labs will perform a mechanical analysis, for an added fee, to determine soil texture. It’s a good idea to get a soil test done before you start using your garden, and now is a good time. Search “soil testing” on the Home and Garden Information Centerwebsite for a video of how to collect the soil sample, what to test for, and how and where to send it.
University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.