Question:

I’m on my fourth fungicide spray, and my scout has recommended adding bifenthrin to my spray. I sprayed Bisiege about two weeks ago, and I’m concerned about potentially flaring spider mites. My understanding is that once you start spraying bifenthrin, you may have to continue using it, and I don’t want to create a spider mite problem if I don’t need to.

For this spray, I’m planning to use Miravis and Elatus. Do you think I should add bifenthrin to this application, or would you recommend leaving it out?

Jordan:

You need 8 worms per foot of row using a beat cloth to be at threshold. Generally, the later we go in the season, especially now to harvest that number could be a little higher. I’d ask what the numbers are before I sprayed bifenthrin. Are you dry or have you had moisture? That affects the spider mite risk. Bifenthrin will miss tobacco budworm and kill about half of the corn earworm in most fields. If you have a population at or above threshold, consider spraying a product that is not a pyrethroid and one that gets the entire complex.

Dominic is our peanut extension specialist working with peanuts. I’ve copied him here for more details.

Reisig:

Bifenthrin isn’t particularly strong on much of the caterpillar complex we see in peanuts. It has also become less reliable for spider mite suppression, and adding it when you don’t need it could ultimately do more harm than good.

I would suggest talking to your scout or doing a little scouting yourself before adding anything. That could pay dividends either way. If caterpillars are below threshold, you may be able to leave the insecticide out altogether. If they are at threshold, you may be better off spending the money on a caterpillar-specific material that will give you better control. Our NC Ag Chem manual has recommendations, but I'm happy to talk through any questions about whether you need to spray or what to spray. 

It would be good to identify caterpillars if they are there. I haven't gotten around to it yet in peanuts, but I have created some pages for soybeans that are useful. There are similar caterpillars in both crops with photos that should help you ID.

Please let me know if you have any questions.