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Archive for the ‘Insect alerts’ Category

This year EPA approved a section 24C approval to use Dermacor X-100 in water-seeded rice in Louisiana. [Click here for a blog post about the registration.] Quite a few producers used this insecticide option in water-seeded rice in Louisiana this season. Mike Stout had extensive research data to support the efficacy of Dermacor in water-seeded rice, but I felt it would be good to verify the activity in commercial fields. Dr. Saichuk used this treatment option at the Vermilion Parish LSU AgCenter rice verification field. According to Johnny, the Dermacor rate was 1.75 oz/A. The variety Cheniere was planted on 4/5/2012 at 120 lbs/A. A true pinpoint flood was applied to the field. Nick Colligan and Stuart Gauthier pulled ten core samples from the field 4 weeks after permanent flood to verify the activity of the insecticide. Nick reported that they did not find any rice water weevil larvae in the core samples gathered.

On another note, one of the field reps reported that they are starting to see armyworms in vegetable gardens in Grand Chenier. I have not received reports of armyworms  in Louisiana rice yet, but it would be good to be on the lookout for this pest. If you treated with Dermacor X-100, the rice should be protected from injury, but CruiserMaxx or NipsitInside will not control army worms. Click here to read about armyworms in rice.

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Pest alert: scout for armyworms in rice near wheat

Armyworms have recently been reported causing injury in Arkansas rice. Click here for a report I read in Oryza news this morning about the armyworm situation in Arkansas. I haven’t had calls about armyworms in Louisiana this season, but we should be aware of the situation with armyworms moving from wheat to rice. A similar situation could occur in Louisiana. The Louisiana wheat crop is maturing more quickly than usual and Sebe Brown recently reported  army worms in wheat in north Louisiana.

So, if you are scouting a rice field near a wheat field, you should watch out for armyworms in the wheat that may march over into the rice. Click here for a fact sheet on armyworms in rice. If you treated your rice with Dermacor X-100 seed treatment it should be protected from armyworm injury. If you used CruiserMaxx or NipsitInside seed treatment you will not have protection from armyworms. Keep this in mind as you make your scouting plans this season.

Rice water weevil sampling plans

Nick Colligan is resuming Karen Nix’s dissertation research studying the relationship between planting date and rice water weevil infestation levels in untreated rice fields. The first field he will sample is located in Vermilion Parish. The field went to flood on Saturday and we will pull core samples in 4 weeks. I’ll let you know what we find.

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Over the weekend Sebe Brown scouted a field in Concordia parish where the stand was being severely reduced by colaspis larvae feeding on seedlings. Problems with this field started on March 16 when the stand began to decline. The plants were described as yellow and stunted. This was a Dermacor X-100 treated hybrid rice field no-till drill-planted at a 23 lbs/acre seeding rate. Surrounding fields were growing nicely. When Sebe scouted the field on Saturday he confirmed that the injury was being caused by Colaspis larvae feeding on the roots of seedlings. The stand was reduced about 40% by this injury. The recommendation was made to establish a shallow permanent flood to avoid further injury. In a situation like this, where the rice isn’t quite ready for a flood, you may lose some injured plants to the flood. The alternative is to wait to establish flood, during which time the colaspis will continue to injure the seedlings and further reduce the stand. Establishment of a flood on the field will prevent further feeding injury by the colaspis larvae and eventually the larvae will die. Note: according to experts in Arkansas it may take up to a month for colaspis larvae to die in the permanent flood. Click here to read more about colaspis. You can watch a video on how to scout for colaspis here. The Dermacor X-100 should provide about 30% suppression of the colaspis infestation. Next season, they will consider using a CruiserMaxx or NipsitInside seed treatment to target control of colaspis. The use of pyrethroids will not provide control of colaspis because they are injuring the crop below the soil line.


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The Louisiana Department of Agriculture and Forestry reported that Mexican rice borer (MRB) male moths have now been collected in pheromone traps in Jeff Davis Parish. These traps were positioned near Iowa, Thornwell, and just south of Welsh. The list of parishes infested with MRB now includes Beauregard, Cameron, Calcasieu and Jeff Davis. So far larvae were confirmed only in Calcasieu parish west of Lake Charles. If you grow or scout cane or rice in any of these infested parishes I strongly urge you to spend time this winter studying the biology and management of the MRB. If you find a larvae or moth that resembles the MRB in rice, cane or other grasses, please get it to your local County Agent for confirmation of identification.

We have created a variety of resources to help in your training about the MRB.

LSU AgCenter scientists prepared a website: Early Management Considerations for Mexican Rice Borer in Louisiana Rice: Click here to read the article. Within the website you will find links to the MRB identification card and field notes and blog postings about the MRB.

We conducted an entomology training at the LSU AgCenter rice research station in Crowley on Sept 13, 2011. The MRB was the primary topic discussed at the training. The powerpoint files are posted at www.lsuagcenter.comClick here to open the website.

The speakers were also video recorded. Here are the video links. Click on the link to open the file.

·         Part 1

·         Part 2

If you have trouble opening any of these links or you need more information on MRB, please contact me. The MRB will be a topic of discussion at the LSU AgCenter winter production meetings.

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I apologize that I haven’t written in a while. We are moving into grant-writing “season”. We are writing a few proposals that address new rice pest problems. You’ll hear more about those projects if they are funded. Just a quick update on the latest news.

We continue to receive reports of rice stink bugs in second crop rice, in some cases with very severe pressure. You can read about this by clicking here. I also received a call today asking what the Re-entry interval for Tenchu 20SG is. The answer is 12 hours – so this means you can safely enter the field 12 hours after the insecticide application.

We have also had some reports of armyworms in crawfish rice – this is in the Evangeline Parish area. Remember that the only thing registered is BT type products, which are really only effective controlling smaller caterpillars. Any other insecticides have the possibility of killing crawfish stocked in the pond.

The LSU AgCenter Extension Entomology program has a couple of trainings this month.

Next week we have the annual advanced entomology training at the Rice Research Station in Crowley on Tuesday, Sept 13 from 9 am to noon. I hope you can join us. I’ll start off by talking about early season pest problems (chinch bugs, bill bugs, sugarcane beetles, etc.). Then we will spend the rest of the training talking about Mexican rice borer management recommendations. Click here for a link to the agenda. We will have three speakers. Speakers will include Mo Way from Texas A&M AgriLife. Mo has studied the MRB for more than 20 years and has graciously agreed to share his insights with us. Dr. Julien Beuzelin (recent graduate of LSU) will talk about his research studying the biology, behavior and secondary host plants (weeds) of MRB. Finally, I will give a presentation on management recommendations and opportunities for cooperators to help us expand the pheromone trapping program. We will have plenty of time for questions from the audience.

Later this month, Gene Reagan and Mo Way are co-hosting their annual MRB site visit in Beaumont, Texas on September 27 to 28, 2011. This is an excellent opportunity to gain first-hand experience scouting for MRB in the field. You will also have the opportunity to learn about the latest research on this pest.

If you are using social media, you are welcome to join the LSU AgCenter Rice Entomology Facebook group page. This is a great place to keep up to date on the latest observations from the field and to share your knowledge with others. Click here to join the group. If you don’t have a Facebook account, you’ll need to create an account first and then request to join the group.

I look forward to seeing many of you at the meetings this month.

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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?

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It’s funny how when you work a field crop, life eventually moves in a pretty predictable cycle. Well, it’s that time of year again. Time to start scouting for rice stink bugs in headed rice, although it does seem to be coming a little bit earlier than usual. This is probably a result of very early planting of rice in some parts of south Louisiana. Unfortunately, field conditions are favoring a bad year for stink bugs. The drought conditions have killed off grasses that would normally serve as a host/reservoir for stink bugs, so there is a chance they will move more readily into heading rice. Recent reports from Arkansas and Mississippi indicate that large populations of rice stink bugs are present in the mid-south. We are already finding them in headed rice fields at the rice research station in Crowley, La.

Last Friday, Johnny Saichuk and I scouted a variety trial in Vermilion Parish where the CL111 was heading first and was already infested with rice stink bugs.

Rice stinkbugs are light tan in color with points on the corners of the pronotum.

I received a call about the field because they noticed quite a bit of blanking in the panicles. They also found a high population of grasshoppers and suspected they may have been causing injury.

Longhorned grasshopper adult in heading rice. You can tell it is an adult because of the wings.

When we assessed the situation, Johnny determined that the blanking was most likely physiological, some sort of effect of weather conditions when the rice was at panicle development (pd). You can read more about it in his field notes. If you don’t receive Johnny Saichuk’s Field Notes via e-mail, please send Johnny an e-mail to be added to his list: jsaichuk@agcenter.lsu.edu. As we examined the grasshopper situation, we found that the grasshoppers were long-horned grasshoppers, which are typically predators. We would not recommend treating for grasshoppers unless they are causing excessive defoliation. Click here to read more about long-horned grasshoppers in rice. Odds are that they were attracted by the rice stink bugs, which we did find to be abundant in the field. We advised holding off on an insecticide application until the rice reached 50% heading. It is very tempting to put out a pyrethroid with the fungicide application at early-heading, but research has shown that this is too early to prevent injury. Putting out an early application will probably just add to the number of times you need to spray the field, while not providing any additional protection. To learn more about rice stink bug management click here.

We have a graduate student, Bryce Blackman, who is currently studying rice stink bugs for his dissertation research. One aspect of his work is to re-evaluate treatment thresholds. At the moment, we continue to use the standard recommendations. To scout for rice stink bugs in the field, use a 15-inch diameter sweep net, take 10 sweeps at 10 different areas around each field. Count the number of bugs collected after every 10 sweeps. In the first two weeks of heading, treat fields when there are 30 or more bugs per 100 sweeps. Pesticides that can be used include malathion, methyl parathion and a variety of pyrethroids including Declare, Karate Z, Mustang Max, Prolex and a number of generics. From the dough stage until two weeks before harvest, treat fields when there are 100 bugs per 100 sweeps. When approaching two weeks before harvest, you can treat with any of the chemicals listed above with the exception of Karate Z and Prolex, which have 21 day pre-harvest intervals. You can learn more about rice stink bug biology by clicking here.

Resistance to pyrethroids has been increasing in Texas, and there is a chance that we could have some issues with resistance developing in Louisiana also. If you have a field where you are finding it particularly difficult to control the rice stink bugs with your traditional control strategies, please contact me so we can sample the insect population. If you have further questions about rice stink bug management, please contact your local County Agent.

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