Questions with Doug Vangundy

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Central Life Sciences

What is an insect growth regulator?

Insect growth regulators (IGRs) are unique and different molecules for use in pest control. They’re not a conventional insecticide where you spray the material and it kills insects. These disrupt the life cycle of the insect. They don’t provide an immediate kill but they prevent the next generation of pests from infesting your plant material.

How does Enstar^® AQ work as an IGR?

It mimics natural biochemicals within the insect. It interferes with normal development processes, as far as when pupation occurs. You have two types of growth in insects — insects that pupate, like whiteflies, and insects that have a gradual metamorphosis and go from the immature stage to the adult stage. In insects that pupate, Enstar^® AQ interferes with the normal pupation so the insect will go from molt to pupae stage, but that’s as far as it goes. It will not emerge as an adult. In the case of an aphid, they will move through the adult stage, but they will become sterile, or in some cases die in that molt, from nymphs into the adult stage.

What other insects does Enstar^® AQ work well on?

It’s a fairly broad-spectrum IGR. It will affect thrips and fungus gnats. When applied to the soil, it interrupts the life cycle of the larvae as they develop in the soil, thereby preventing the adults from emerging and causing a problem. Fungus gnats are primarily a nuisance pest, and in large numbers they can certainly be an annoying problem.

Enstar^® AQ is particularly effective on whiteflies in poinsettia production. When the plants start to bract, whiteflies attack the bracts and the damage reduces the plants’ value. Use Enstar^® AQ as a preventative approach for whiteflies.

How can growers apply Enstar^® AQ?

You can apply Enstar^® AQ by itself, diluted in water and applied through a power sprayer or compressed air sprayer, or backpack blower. Whiteflies and some other pests are often underneath the plants and stems, so apply to those areas where the pests are primarily attacking the plant.

Enstar^® AQ is also labeled for a tank mix. It can also be mixed with Mavrik Aquaflow^®. Just follow the use directions on both packages. The more stringent label will apply when making a tank mix.

How do you prevent insects from developing resistance?

An IGR can be beneficial in that regard because you’re providing two different modes of action on the insect. A pyrethroid insecticide is a sodium channel blocker. And a lot of those (insecticides) have been around for a while, so there is resistance in the field for certain insects. Mixing in an IGR gives you a different control method. So, if you have a resistant population, let’s say an application only kills 50% because of resistance, put an IGR in there, and those that survive the application will produce either dead pupae or sterile adults. It helps remediate that resistance that is building up in a population with conventional insecticides.

Should I be concerned about phytotoxicity in an IGR?

In general, most IGR products are low in phytotoxicity. Enstar^® AQ, being a water-based formulation, doesn’t have any of the oils or solvents that can sometimes cause a phytotoxicity issue. But as a general recommendation, if you’ve never used a particular product before I would take a small amount of plant material and spray that material and watch it for a couple days to see if you have any phytotoxicity before you spray the whole greenhouse with it. Look for browning of the margins of the leaves or spotting where the drops dried on the leaves or the flowers. Those are the two major signs of phytotoxicity.

For more: centralgrower.com