8/30/2011 7:34:10 PM
This week I’ve received a few calls from consultants about high rice stink bug counts in late-planted rice and second crop. We don’t have recommendations for second-crop rice in our publications, largely because this crop has not historically been important enough (economically) to protect. With advances in variety yield potential and improvements in second crop management, the second crop may be valuable enough to warrant protection (in some situations). This is an area where we need to spend more time on research. We would recommend that if the thresholds for first crop (30 per 100 in first two weeks of heading and 100 per 100 after first two weeks of heading) are exceeded in second crop, then you should consider using an insecticide. Click here to read more about rice stink bug biology and management.
There are a variety of pyrethroid insecticides registered for stink bug management in rice and these can be used in second crop rice – as long as you observe the pre-harvest interval and any restrictions on the total amount of product applied during a single season. This season, we also have a Section 18 approval for Tenchu 20SG – a neonicotinoid chemistry that I discussed in a blog posting you can view by clicking here. If you have severe pressure in your rice field, or you anticipate you will have to make a second pyrethroid application (because you are applying a little early in the heading of the crop), you may want to try the Tenchu. We have had one field location in north Louisiana where Tenchu was put out side-by-side with Karate. The infestation was severe with between 10 and 20 stink bugs per sweep. You could smell them when you walked across the field. 48 hours after treatment, the count was down to 3 per 100 sweeps in the Tenchu-treated area and more than 30 in the Karate-treated portion. The pyrethroid-treated portion was retreated. This is an example of where this new chemistry might fit in certain situations. It appears to be a good fit in fields with high populations, if you anticipate an ongoing infestation (perhaps nearby fields are being harvested – making your second cropped rice one of the only places for rice stink bugs to infest), or if you are applying early in heading and expect to put out a second pyrethroid application.
Remember that after hard dough the rice is no longer vulnerable to stink bug injury. And while it is disconcerting to see rice stink bugs in the hopper when you are harvesting, they are not harming the crop. Of course, they will probably leave that harvested field and infest surrounding fields.
Are you finding severe stink bug infestations in your region?