Questions with JC Chong

Supplement - Cultivate ‘21

Learn about what make certain pests more likely to develop pesticide resistance and how to deal with them.

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June 7, 2021

Q: What can attendees expect to learn from your session?

A: There are a lot of myths out there about pesticide resistance. One of the big things I want to do is debunk some of those myths. The other thing would be to provide practical advice, or even some examples of how you can develop a rotation program.

Q: What are some of the myths you’ll cover in your talk?

A: One that is often heard is that insecticide resistance is eventually inevitable. There are actually a lot of things that we can do to stop that from happening. It’s not inevitable. We will have to get that across so people have somewhat of a ray of hope. Otherwise, the grower says ‘10 years from now, I won’t be able to manage any of my thrips population. I might as well give up now.’

Q: What pests do you plan to cover?

A: For the nursery operations, what I would cover mainly would be thrips and spider mites. Those are the two major ones I was thinking about because they are our major pests and also they have a nasty reputation for developing resistance pretty quickly.

While I am talking about those two pests, I will also bring up some examples to demonstrate to attendees how you can develop a program and some of the things that you need to consider when you’re developing your program.

Q: Why are some pests more likely to develop resistance to pesticides?

A: Generation time is one of the biggest considerations when it comes to trying to predict which pest population might become resistant faster. So the reason why resistance develops is because there is a particular gene that provides the insect population with the resistance. And if you have more generations that gene spreads through the population faster.

That’s why we keep seeing spider mites and thrips becoming resistant and whiteflies becoming resistant. Spider mites complete development in seven days and thrips and whiteflies in about two to three weeks. That means you have maybe six, eight to 10 generations per year. If you are using the same insecticide over and over again, the pest population basically has a lot more time to develop the resistance.

Q: What can be done once they’ve already developed resistance?

A: The first thing I would do is to figure out where there is really resistance. Another commonly misunderstood fact is that when you do not achieve the same level of control as you used to, it is not always resistance. Sometimes it is application issues. Maybe you’re not using the right application rate. Maybe you’re not achieving the right coverage, or you’re not applying at the right time against the right life stage. So the first thing I would do is to figure out if it is really resistance or not. If you’ve got to the point where you think ‘Surely, I’ve done everything right.’ Then I’m going to start thinking about resistance.

The next step is what did I use before? Is there something in there I keep using? And is that the one that I’m starting to lose efficacy on? And if that’s the case, that is the one product I need to pull out from my past management program. Just pick it out and then replace it with a different mode of action. And if it is a resistance issue, and if the pest population is still susceptible to the new mode of action, then you will see a reduction in your pest population again.

Q: What does the title mean – good things come in threes?

A: That’s basically a play on the whole process of rotating modes of action to build a rotation program because I often have folks ask me how many modes of action they should put in their program. If you have one, that’s not a rotation. If you have two, that’s not much of a rotation either. So you want to have at least three and more is even better.

Want to go?

Good Things Come in Threes (or more): Insecticide Resistance Management for Nurseries

Sunday, July 11, 4:15 p.m.-5:15 p.m., Union Station Ballroom B

JC Chong is a professor and extension specialist at Clemson University.