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Posts Tagged ‘vermilion’

We have finally concluded all of the core sampling for our demonstration test this production season.  We have gathered all the data and Anna conducted a statistical analysis.  In this analysis each location is treated as a replicate.  

Our demonstration test was conducted in all the Louisiana parishes highlighted in purple.

 

We had a total of 15 sites included in our test this year.  We started this season with 5 locations designed to evaluate rww management tactics.  An additional 5 sites were set up to evaluate colaspis management.  We did not have any colaspis infestations in the test sites.  We gained three more weevil test sites that had been planted out either by seed companies or a cooperator, who requested we take samples.  We wound up with a total of 10 locations that were included in the overall data analysis.  More than 500 core samples were processed to generate this dataset – that’s a lot of backbreaking work to pull all the cores and then to wash all that mud from the  roots!  Thanks to our cheerful, hardworking crew for completing this task without complaint.  

We collected weevil cores from all sites 4 weeks post flood.  Our standard method is to take 10 cores per treatment, in a zig-zag pattern across the field, making sure to pull cores from the edge and middle of the cut.  

   

A few trends broke out in the dataset.  In Acadia and Jeff Davis Parishes, we had a relatively light infestation with weevils, except at one location (Lawson Farm) where we had about 10 larvae per core in the untreated check.  In Vermilion Parish we had low to moderate infestations.  In Concordia Parish we had an average of 10 larvae per core in the untreated check.  In Evangeline Parish we had a relatively severe infestation with untreated counts averaging from 10.8 rww larvae per core at the LaHaye farm to 15 larvae per core at the Morein farm site. Our highest population was in St. Landry Parish where we had an average of 21.9 larvae per core in the untreated check.  While, in Tensas Parish (our most northern location) we had an extremely light infestation with zero larvae per core in the untreated check and the highest count of 0.15 larvae per core in the Dermacor X-100 treated cut.  Interestingly at this location, we had a fairly severe infestation in the 2008 production season.  The  graph that follows summarizes the average number of rww larvae per core when we analyzed the entire dataset.  

Average number of rice water weevil larvae per core (calculated from 10 cores per field or cut). Different letters indicate a significant difference in the treatment effectiveness.

 

Overall, Dermacor X-100 provided the best level of weevil control, followed by pyrethroid (either Karate pre,Karate pre + mustangMax on fertilizer post, or Karate post) and CruiserMaxx.  Dermacor X-100 provided significantly better control than the other two treatments.  There was no signficant difference in the core sample average between the pyrethroid and the CruiserMaxx seed treatment. 

Unfortunately, the results from the Hybrid test plots (25 pound or less seeding rate) did not provide any more clarity about the ability of CruiserMaxx to provide effective weevil control at the low seeding rates.  We plan to repeat the demonstration test again next season, particularly focusing on the low seeding rate question.  Mike Stout has some small plot replicated research that may also clarify the question of effectiveness of CruiserMaxx at low seeding rates as currently labeled.  

This was certainly an interesting weevil season, and we learned a lot about weevil management, and just how difficult it can be to scout for adults and properly time insecticide applications.    

We greatly appreciate the support and cooperation of all who are involved with the demonstration test.  Please contact your local county agent, or me, if you have any questions about our observations this season. 

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Yesterday, County Agent Stuart Gauthier pulled core samples at the test site farmed by Alden Horton.  Alden wanted to really study the management of rice water weevils in a water-seeded system.  In this case, the only option for pesticide management is the use of pyrethroids.  The first step was to spend the time to scout properly before and after permanent flood for the presence of rice water weevil adults.  Stuart worked closely with Dr. Saichuk, myself and Alden to check the field on a regular basis – at least weekly, but often times more frequently.   It was a tough decision to decide on weevil management at this site. 

Permanent flood was applied on April 23, 2010. We scouted before flood, did not find weevils, so we decided to hold off on spraying.

On May 6, 2010, Stuart scouted the fields with Johnny and Alden.  At this time, the rice was at mid-tillering and rice water weevil adults (including mating pairs) were found in the field.  The population was sparse, but there are often many more that you don’t see.  We recommended an application of 2.0 fl oz of KarateZ.  Two small cuts that were separated by levees from the treated fields were left untreated for comparison.

We gathered 10 cores per field 4 weeks after permanent flood.  This is when you will see a peak in the population.  We processed the cores at the rice station yesterday – 10 cores per field – untreated and Karate treated.  In the untreated check, the average number of larvae per core was 4.8.  By comparison, the Karate treated field had a population of 0.9 larvae per core.  Much research has led us to conclude that each larvae can cause 0.5 to 1.5% yield loss.  Based on this estimate, we would predict that a yield loss from 2.4 to 7.2% may be experienced at this field site.  It appears that a treatment was called for at this location.

We’ll let you know how it looks as the season progresses.  We will probably have a stop here at the Vermilion Parish rice tour on July 6, 2010.

Our sincere thanks go to Mr. Alden Horton for cooperating in this demonstration test.

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This morning I met with County Agent Stuart Gauthier, Rice producer Richard Hardee and Consultant Chuck Greene at the demonstration site in Vermilion Parish just outside of Gueydan. 

Meeting with cooperators Chuck Greene, Richard Hardee and County Agent Stuart Gauthier near Gueydan, La.

This part of the state is really hurting for water – I read the local paper where the headline was the extreme need for water.  Some parts of the parish had less than 1/2 inch of rain in April, and other areas had no measurable rain.  Compounding the lack of rain is the lack of fresh surface-water available.  The parish is still suffering from the effects of salt water intrusion caused by the hurricanes. 

Fortunately, Richard has access to a well, and we are completing the application of permanent flood on this site.  Mr. Greene walked the field with Richard last week to make the decision about a pyrethroid application before permanent flood.  Weevil scarring was not abundant in the field and he was hard-pressed to find an adult weevil.  The decision was made to wait for a pyrethroid application until after permanent flood.  Permanent flood is the trigger for rice water weevil adult oviposition (egg laying).  

Today we scouted the field that was slated to receive a pyrethroid application – if scouting determined it to be necessary.  We were able to find about 10 rww adults, 2 of which were a mating pair.  

Rice water weevil adult.

 

We also found an abundance of fresh feeding scars.  

Rice water weevil scars on a rice plant leaf.

 

Stuart also noted that many of the rww adults he found were below the surface of the water – these are probably females laying eggs.  

Chuck Greene and I discussed our options and decided a weevil treatment was needed.

 

Chuck and I discussed the situation with Richard and decided that a pyrethroid spray is now warranted.  We recommended between 1.7 and 2 fl oz per acre of Karate be applied sometime this week when the wind is calm (today was pretty windy).  We plan to go back in and scout in one week to make the decision about the need for a second application. 

Also at this site, we will possibly evaluate draining a cut to look at the effect of draining on rww population in an infested field.  I’ll keep you updated on how that goes.  We will take core samples in approximately 4 weeks to evaluate the insecticide treatments.(Photo credits: all photos taken by Anna Meszaros, LSU AgCenter.)

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Rice Farmer Alden Horton and County Agent Stuart Gauthier discuss plans for the rice water weevil demonstration test.

Today I drove to Kaplan, Louisiana (Vermilion Parish) to meet with cooperators for the rice water weevil demonstration.  Stuart Gauthier (County Agent) and I met at the G&H store in Kaplan, and then headed out to meet Mr. Alden Horton – rice farmer in Vermilion Parish.  I had mentioned at the winter production meetings that I wanted to look at some water-seeded rice fields to get a feeling for what the weevil populations were like in these situations.  Alden volunteered to discuss this with us.  This series of cuts is located on Highway 14, not far from Kaplan and Gueydan, LA.  I’ll send out a map at a future date.

At Alden’s farm we will be comparing an untreated cut to fields that receive a Karate application with the second application on Newpath herbicide.

Rice water weevil feeding scars.

A second application of Karate will go out if we find rice water weevil adults or fresh feeding scars one week after flood.  We will possibly have a meeting at  the field when we make the treatment decision. I’ll keep you posted.

After meeting with Mr. Horton we headed over to Gueydan to meet with Mr. Richard Hardee.  If the weather cooperates, Richard’s rice will be drill-planted, or broadcast and covered.  We will be comparing Dermacor X-100, CruiserMaxx, Pyrethroid, Drained, and an untreated check.  I’ll be posting the field map soon after the fields are planted.

When I stepped out of the truck in Kaplan this afternoon, I was greeted by the familiar smell of boiled crawfish.  Maybe spring has finally arrived in southwest Louisiana???

I’ll be visiting cooperators in Evangeline, St. Landry, and Acadia Parish in the next couple of days.  I’ll keep you posted on progress as we lay plans for the demonstration work this summer.

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