Rice Stink Bug Update – July 22, 2022

Rice stink bug populations appear to be very high in a lot of areas of the Delta this year.  To make matters worse, we are getting numerous reports of poor control with pyrethroids.  There were several cases reported late last year and it appears pyrethroid resistance is spreading.  Our counterparts in Arkansas are reporting poor control in their state as well.  In fact, they experienced widespread failures last year and were able to get an emergency exemption to use Endigo ZC to manage rice stink bugs in rice.

Unfortunately, there are very few labeled products beyond pyrethroids.  The only options are Tenchu and malathion, but those products are extremely limited in the state.  In fact, I heard from one retailer in Bolivar County today that they used the last of their Tenchu earlier this week.  It also seems that a lot of retailers don’t have malathion available and have not for several years.

As more rice begins to head, hopefully the pressure will subside a little bit as the stink bugs get diluted across more acres.  Even when that occurs, I expect a lot of fields will need to be sprayed over the next 10 days to 2 weeks. One thing that is important to remember is that the greatest yield losses from rice stink bug occur within the first 10 days to 2 weeks of heading, so it is important to maximize control at that time. I know this is a difficult situation for growers with rising application costs due to fuel prices. I’m hearing fees for aerial application are considerably higher this year than last year (as would be expected). That is another reason why maximizing control is important.

Historically, the majority of rice in Mississippi has only needed one application with a mid-rate of a pyrethroid to control rice stink bug.  In previous years, we rarely needed to make 2 applications. That is likely to change this year as we have already heard of several fields needing 2 applications. Again, with high fees for aerial application, this is not an ideal situation.

So what do we need to do moving forward?

If you can get it, use malathion or Tenchu.  The rates are tricky in this situation.  Typically, I would suggest using the highest labeled rates in an attempt to extend residual control.  However, with limited supplies, you may be better off using lower rates to try to cover as many acres as possible.

If you are unable to get either of those products, use one of the labeled pyrethroids at its highest labeled rate.  Rice stink bugs will move down lower in the canopy during the hottest times of the day, so try to schedule applications early in the morning or late in the evening when stink bugs are up on the panicles actively feeding.

We are currently working with the Bureau of Plant Industries to try to find some alternatives, but that is going to take some time.  In the meantime, please let us know if you have failures.  We currently have a graduate student, Ms. Mary Jane Lytle, working on rice stink bug resistance and management. It will be beneficial for us moving forward if we can accurately determine the spatial distribution and levels of resistance in the state.