Q. In a previous post you talked about whiteflies.
https://xtremehorticulture.blogspot.com/2015/02/how-to-control-whiteflies-on-tomato.html
https://xtremehorticulture.blogspot.com/2015/06/the-whiteflies-are-coming-whiteflies.html
What do they look like and how do I know if my plants have them?
A. Whiteflies are commonly found on many different
vegetables during summer months, like tomatoes, squash and melons. But they are
not as common to ornamental trees and shrubs. As far as ornamentals go, they
can be a problem for ash trees, citrus, pomegranate, gardenia, hibiscus, iris,
flowering annuals, gladiolus and some others. Whiteflies are small insects,
brilliant white in color as winged adults, that suck plant juices from leaves
and young stems much like aphids and leafhoppers.
If you
are observant and constantly tinkering around your plants, you will notice them
during the heat of the summer swarming in the air when disturbed from plant
leaves like white “dandruff”. This is an indicator to look at the undersides of
leaves where you will find a massive number of unwinged young’uns sucking
“juice” from the plants.
If you
are not as observant, you might notice sticky, sugary sap dropping on plant
leaves from the feeding just above it. Or you might see columns of ants
attracted to this sugary sap, going back and forth to their underground nest
carrying this sugary food. Sometimes a black mold will grow on this sugary sap
in more humid climates, just like it will with aphids. This black mold is
called “sooty mold” which can cause lots of plant damage if left unchecked.
The
adults can fly while the young-uns can’t.
So that swarm of white adults you see flying are adults only and a sure
sign that feeding damage is underway.
It’s
winter now so you will not see whiteflies on plants unless they are on plants
in warm spots like greenhouses. They are tough to control because they are
resistant to many chemical controls. If
you find them early enough, removing infested leaves might keep them in check.
Repeated soap and water sprays will kill them. Winter applications of dormant
oil to woody trees and shrubs in January will help suppress their numbers in
the summer from overwintering adults.