Posts Tagged ‘armyworm’

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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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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I had planned to write about rice stink bugs today, but something else came up during our field work. Yesterday, at the Simon field site tour stop, Mr. Eddie Eskew told me about a field of rice that was suffering from a severe infestation of armyworms. Up to this point in the season, I’ve had a few calls about armyworms, but nothing out of the ordinary. We wanted to collect caterpillars to add to our lab colonies on campus, so we headed to the field today. I thought you would like to see what can happen when armyworms march across a rice field.

Last week this field of XL729 was progressing nicely. You can see in this picture how nice the surrounding fields are looking.

Field suffering from armyworm infestation to the left of the levee and a healthy field to the right of the levee.

The grower called Eddie on Tuesday when he found armyworms infesting the field. They had marched in from the tree line on the edge of the field and quickly progressed across to the field road. No appreciable damage was observed in surrounding cuts, although we did notice birds in a neighboring field, which were probably feeding on armyworm caterpillars.

Cattle egrets (the white birds) and "trash birds" (the black birds) as they are called by my student worker. Birds are a good indication of an insect infestation.

When we pulled up to the field it was not hard to observe the significant injury the armyworms were causing to the plants.

Eddie Eskew (G&H) collecting armyworm caterpillars in an infested field.

This particular field was planted in late April with the intention to harvest a rice crop. It will also be stocked with crawfish for harvest next spring. This creates complications when it comes to pest management. Insecticides which would effectively control the armyworms will be toxic to crawfish. For this reason, we cannot recommend any insecticides for control. If the armyworms were younger (most were large and probably near pupation) we would consider using Bt to control the population. The only measure that can be used is to bring flood water and drown them out. In this field, water had been on the field for about 48 hours and many of the caterpillars were still feeding on plants. On the positive side, they no longer had access to the crown of the plant. This is important for a rice plant because the leaves arise from the crown. You can think of this as being similar to your lawn. You can hit it with a mower and it will regrow every week (if we get any rain). This is also true for rice. Ideally we would not be mowing the rice plants, the plants that survive will likely be stunted. We collected some caterpillars to add to our lab colony. There is a good chance that most are either parasitized or will die of disease. This is what we typically find in field-collected armyworms. Unfortunately, the naturally occuring pathogens and parasitoids that attack armyworms in the field usually do not act quickly enough in a rice field to provide natural control and prevent severe injury. Following is a series of pictures of the field injury and caterpillars in the rice.

Field of XL729 that is suffering from an armyworm infestatiohn. The armyworms have been in the field for about 72 hours. Flood was applied about 24 hours after the initial infestation.


Many armyworm caterpillars feeding on a rice plant.


The armyworms were clustered onto the stubs of the plants mowing them down to the surface of the water.
On our way to the field I received a call from Kent Guillory, a consultant in Evangeline Parish, who also was treating a field infested with armyworms. I’d deduce from these two calls, that it is now time to start keeping an eye out for armyworms. You can see from our observations at this field that they can move in and cause significant injury in as little as a day. If you can preserve the crown of the plant it should be able to recover.
Tomorrow we will discuss rice stink bug infestations and management recommendations.

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