Fire ants can harm vegetable gardens
September 8, 2005
RON GILLIG
Victoria County Master Gardener
One of the primary responsibilities of master gardeners is
to assist in providing answers to questions received via telephone calls at the
Soil preparation should be taking place now - and even some
vegetables should already be planted by now. But just digging in the soil gets
my blood boiling when fire ants find me. Fire ants are just about in every
county in the state now - and while we can't eliminate them, there are some things
we can do, even in our vegetable gardens, to minimize damage and pain caused by
these pests. The information contained in this article will serve for both fall
and spring vegetable gardens......
Vegetable gardens attract many different insects because
gardens are well watered and contain oily seed pods or plant materials - and
even other insects that fire ants feed on. These conditions are just what the
fire ant is looking for. Once in the garden, the fire ant has been known to
tunnel into potatoes underground, tomatoes above ground and feed on okra buds
and developing pods. Insects found in the garden are usually considered prey by
the fire ant. The aphid is one exception. Fire ants will protect aphids from
their natural enemies for the sugary liquid waste they secrete called honeydew.
As we all know, some of us are especially vulnerable to the
sting of the fire ant. The stings are painful and you can lose valuable
gardening time trying to remove several hundred ants from your shoes, much less
the pain and itching that lasts up to a week. How can you get so many bites so
quickly? According to Nathan Riggs, extension agent-Integrated Pest Management
(IPM) in San Antonio, we need to realize that along with the queen laying as
many as 800 eggs a day, each mound can have about 200,000 workers protecting
the mound and bringing in food. Once disturbed, they communicate quickly among
themselves saying, "Somebody is about to get us, let's go
get them first."
What can we do in our gardens ... places where we raise our
food to feed our families?
Let's look at some options. According to Riggs, the only
fire ant bait approved for use in the garden is Extinguish, which contains s-methoprene. It is an insect growth regulator and considered
safe for all mammals. Other baits, containing products such as hydramethylnon, abamectin, fenoxycarb or pyriproxyfen, are
not approved for vegetable garden use and should only be applied to the
perimeter of the garden. Baits are attractive to worker ants inside and outside
the garden; however, it will be six to eight weeks for effects to begin.
Pyrethroid insecticides, including
esfenvalerate and cyfluthrin,
are approved for use against fire ants in the garden if the wording for this
use is found on the label. Not all companies making these products apply for approval, even though it is the same pesticides others get
approved. These two pesticides will kill foraging ants on contact.
Carbamate insecticides containing carbaryl are effective against fire ants. You must read the
label to determine if these products can be used against fire ants in the
vegetable garden.
The latest in organic fire ant control is spinosid. This new organic product works quick and well
according to the
Organic methods for fire ant control in the garden, using pyrethrins plus diatomaceous earth as a mound drench, will
also provide a quick kill with short-term residues. I have used this method
myself with good results. Diatomaceous earth applied alone as
a dust or water suspension to the mound may kill a few ants and will probably
cause the colony to move but will probably not eliminate them. Other
organic plant-derived products containing d-limonene (citrus oil extract), rotenone or pine oil extracts are approved against fire
ants and may provide some relief.
The last method of managing fire ants to be addressed here
is non-chemical. One or 2 gallons of very hot to boiling water poured on new
fire ant mounds will kill the mound 60 percent of the time. You must be careful
not to cook your plants or your feet.
By now, you are probably wondering why I did not provide
many product names in this article. There are quite a few differently named
products containing the same active ingredients I have discussed. Again, these
products may or may not be approved for vegetable garden use against fire ants
depending on the company's approval granted through the Environmental
Protection Agency (EPA). When purchasing pesticides, shop by active ingredient
and approved use to keep ourselves, our environment and others safe. Remember:
READ THE LABEL, FOLLOW INSTRUCTIONS AND HEED WARNINGS.
If you are interested in fall vegetable garden plant lists
and timeline guides by date for direct seeding and transplanting fall vegetable
plants, refer to a previous article in this column archived at the Master
Gardener Web site http://www.vcmga.org/2004_Aug19.html
"Dig in Now: Get Ready for Fall Gardening."
And speaking of fall, don't forget to sign up for the Fall
Gardening Symposium and plan to shop the Master Gardener Fall Plant Sale on
Saturday, Sept. 24 at the 4-H Activity Center and Officer's Club at