Q. This past year our pomegranate bush had a lot of
whiteflies. I know they do damage to the bush and so I want to control them
organically and naturally. How would you suggest doing that?
A. Whiteflies are a bad insect problem for any plant. I
would rank them with the “hard to control” list of insects. In small numbers
they can be tolerated but their populations grow so quickly that small numbers
lead to large numbers very fast. For this reason, it’s important to get them
under control early, as soon as you see them, in late spring and early summer.
Don’t wait.
Damage
is associated with their feeding. Their feeding supports a quick growth in
their population as summer temperatures get hotter. They love the heat and so
they’re not seen around much until June or July. Once you see them and it’s
hot, watch out! You are behind the curve and they are way ahead of you!
In late
May begin weekly inspections of the leaf undersides for whitefly adults. The
adults look like living dandruff. You probably won’t see the eggs or immature
forms because they are so small, but you will see the adult females preparing
to lay eggs or protecting their young so that they can build their populations
as quickly as possible. Pull these leaves off when you see them infested and
dispose of them or vacuum them with a Dust Buster. This practice slows their
populations way down.
Control is two-pronged. First, spray pomegranate bushes on a warm day in December and then again in January with a dormant oil. You can use the commercial brands of dormant oils and horticultural oils or you can use soybean oil, canola oil, rosemary oil or cinnamon oil.
Spray all the branches after pruning, top to bottom, and spray a little extra shot at the base of each tree. This spray suffocates insects that might be hiding out during the winter months. It is the most important spray for controlling insects that will be problems in 2020.
At the
beginning of June, hang bright yellow or bright blue thick construction paper
in the tree smeared with Vaseline. Whiteflies fly toward bright yellow and
bright blue objects and the Vaseline causes them to get stuck. As these traps
begin to fill, replace them with new ones. It might look a little funny, but
light reflected from aluminum foil repels them.
If
populations are totally out of control, spray with an insecticide to get their
populations back under control. As a homeowner, use pesticides when all other
attempts fail. Spraying with insecticides, however, have other consequences and
should be a last resort.