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Posts Tagged ‘grasshopper’

If you reach way back in your memory, some of you may remember completing the 2009 Louisiana rice insects survey at one of the winter production meetings back in January or February of this year.  The surveys were distributed in Louisiana, Texas, Missouri, Mississippi and Arkansas this year.  Anna and I have recently completed a summary of the responses and I’ll use this series of posts to provide an overview of a few observations.  Keep in mind that the trends reported in this posting relate to the 2009 production season, not the 2010 production season.  We will distribute a survey about the 2010 production season at the winter meetings in January.

Participants from the circled Louisiana parishes completed our survey.

184 survey sheets were processed from the following states: Louisiana (146), Texas (47), Missouri (5), Mississippi (2), and Arkansas (1).  In Louisiana, respondents from the following parishes completed surveys: Acadia, Avoyelles, Beauregard, Calcasieu, Caldwell, Cameron, Catahoula, Concordia, East Carroll, Evangeline, Franklin, Jefferson Davis, Lafayette, Madison, Morehouse, Ouachita, Point Coupee, Rapides, Richland, St. Landry, and Vermilion (see map above).  

We would like to thank all rice industry members who participated in this survey and helped to distribute the survey sheets. This survey was supported in part by the Louisiana Rice Research Board and the Southern Region Integrated Pest Management Program.

My comments will mostly be confined to the Louisiana responses at this time.  The demographics of the participants in Louisiana was broken down as follows: rice farmers (79%), consultants (12%), dealers (7%), and others (10%, e.g. county agents, researchers, manufacturer representatives, marketing managers and land owners).  The length of time that repondents have been involved with rice production varied from less than five to more than forty years, with the greatest percentage (18%) with 26 to 30 years of experience.  Approximately 76% of the survey respondents farmed or consulted on less than 2500 acres of rice in the 2009 production season.

The first series of questions related to insect infestations which were severe enough to warrant an insecticide treatment.  92% of Louisiana respondents reported that they had some fields that required treatment for rice water weevils.  88% of the respondents reported problems with rice stink bugs.  While fewer people reported infestations of grasshoppers (24%), armyworms (24%), and chinch bugs (23%).  The next most commonly reported insects were the rice leafminer (12%), stalkborers (11%) and colaspis (11%).  Less than 10% of repsondents reported infestations of rice seed midge, aphids, rice levee bill bug, or south American rice miner that warranted an insecticide treatment. 

We asked more detailed questions about rice water weevil management strategies.  A large portion of our time is dedicated to rice water weevil management because this insect traditionally causes the most significant damage to Louisiana rice production from season to season.

In both the 2008 and the 2009 production season survey, we asked the following question:

If rice water weevils were a problem in your rice field(s), which method did you use to control or prevent a rice water weevil infestation? Note that respondents could choose more than one answer since they are completing a survey that relates to more than one production field.  That will explain why the total response does not equal 100%.

In 2008, among 163 respondents in Louisiana, the most common method used to control or prevent rice water weevil was drained field (43%).

In 2009 among 130 respondents in Louisiana, the most common method used to control or prevent rice water weevil was Dermacor X-100 seed treatment (52%).  In 2009, this was the only seed treatment available for use in rice.

Method used to control rice water weevil in Louisiana rice fields

2008 Percentage (%) 2009 Percentage (%)
Drained field 43 34
Post-flood treatment with a foliar spray of pyrethroid 39 44
Pre-flood treatment with a foliar spray of pyrethroid 36 37
Pre-flood treatment with a pyrethroid impregnated on fertilizer 21 22
Post-flood treatment with Trebon 20 10
Early planting to avoid infestation 18 31
Dermacor X-100 Seed Treatment 17 52
Pre-flood and Post-flood treatment with a pyrethroid 13 N/A
Delayed application of permanent flood 13 27
Pre-flood treatment with Trebon 9 7
Nothing 6 7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

There was a decrease in the percentage of respondents who reported that they drained a field for weevil management while their was a substantial increase in the adoption of seed treatments and cultural practices (early planting and delayed application of permanent flood) which should result in decreased weevil injury.

The next installation in this series of blog posts will focus on questions related to rice stink bug management.  Do these observations reflect what you experienced in the 2009 or 2010 production seasons?

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I’ve had a few calls about grasshoppers in rice – particularly in the south-central Louisiana.  I called Mo Way (Texas rice extension entomologist) to discuss this with him.  I know they had some trouble with grasshoppers in Texas earlier this season.  As Mo said this is an odd year, so we are seeing some out of the ordinary insect problems.  Here’s a little information about grasshoppers.     

Possible damage: Grasshoppers can cause defoliation, but unless you exceed 20% defoliation of rice that is actively growing and past the boot stage, then we would not generally recommend a treatment.  Grasshoppers can also feed on grains as they develop in the panicle and this can cause blanking as grains mature – you might see a white, empty hull on a panicle.  The grasshoppers cause this damage by feeding near the bract at the base of the grain.  This damage is usually not severe enough to warrant a treatment.    

Long-horned grasshopper adult - this insect could damage the rice, or actually help out by eating rice stink bugs.

Beneficial insect: Long-horned grasshoppers in particular (bright green with long antennae) are omnivores – they will feed on vegetation and also other insects.  In some cases they can help to manage your rice stink bug infestation by eating the rice stink bugs.     

Recommendation: We do not recommend applying an insecticide for grasshoppers unless you are certain they are causing enough of a reduction in yield to cover the cost of a spray.  It is possible that a pyrethroid application for rice stink bug or stem borer will also control grasshoppers.    

Please contact your local county agent, or me, if you have a severe infestation of grasshoppers and you feel it is causing damage to your rice.

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County Agent Donna Lee (East Carrol Parish) hosted a field meeting at the farm of Mr. Garrett Marsh in Madison Parish in cooperation with County Agents RL Frazier (Madison Parish) and Dennis Burns (Tensas Parish).  We started bright in the morning and the rice was busy shedding water in the heat.  Dr. Johnny Saichuk described this in a field note a few weeks back.  (in case you didn’t already know this – you can click on the pictures to enlarge the image size on your computer screen)  

These droplets of water are called guttation - the rice is releasing excess water in the morning. This is what causes high humidity around rice fields in the early morning hours.

 

These high humidity conditions pose a bit of a challenge when taking pictures, but there were way too many critters to miss the chance.  The rice is just starting to head and the rice stink bugs were poised and ready to strike.  

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

 

Remember that the threshold for treatment in the first two weeks of heading is 30 per 100 sweeps, and after the first two weeks of heading to hard dough is 100/100 sweeps.  Be sure to observe preharvest interval restrictions.  Mike Stout and I are co-advising a graduate student who is studying rice stink bugs.  We may be revising thresholds in the future.  

We had walked out in the field to look at some suspect red rice – this is easy to spot because it usually has a light yellow color, pubescent (hairy) leaves, and awns when the panicle emerges.  Johnny recommended rouging the weedy red rice out of the field before it has the chance to go to seed.  A big problem can grow from a small patch of plants.  

Patch of red rice in a conventional rice variety.

 

As we were examining the red rice I couldn’t help but notice an abundance of long-horned grasshoppers in the field.  This included adults and immatures.  In most cases, even if the grasshoppers feed on rice they won’t do enough damage to warrant a spray, but sometimes they can be severe.  This is a good thing to be on the look-out for as your are scouting your rice.  

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

 

Longhorned grasshopper nymph - notice the long antennae.

 

Before we had even driven to the field, the farmer – Mr. Garrett Marsh had mentioned some small black and white insects on the Johnsongrass at the edge of the field.  As I had suspected, these were chinch bugs.  Chinch bugs can be sneaky pests that prefer to hide down inside the sheath of plants.  As we examined the weeds, we found a variety of life stages from nymphs to adults.  

Notice the difference in coloration from the nymph to adult stages. Nymphs molt (shed their skin) to go from orange, to orange with tan band, dark brown with tan band, to finally the black adult with a white hourglass.

 

This is what chinch bugs often look like when you are scouting for them in grasses - this is the rear view of an adult hiding out in the leaf sheath to avoid the heat.

 

Notice the distinct hour glass that you can just barely make out from the rear view of the chinch bug adult.  At this stage of the game, there is no need to treat for chinch bugs even if they were in the field.  Although, I have had some reports of chinch bugs causing damage to panicles in headed rice – Johnny Saichuk featured this damage in his field notes.  It is good to remember that insects do not follow rules and will many times surprise us with what and when they decide to damage the crop.  

This week we have field meetings in Vermilion Parish (Tuesday afternoon) and Richland Parish (Wednesday morning).  Please contact county agents Stuart Gauthier or Keith Collins for more information.

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This is a guest post from Acadia Parish county agent Barrett Courville.  Barrett sent out this report to his e-mail list and I thought you would be interested.  Please keep in mind that all chemical recommendations are specific to Louisiana.

Monday was the official first day of summer and the temperatures sure are reflecting that.  Daytime temperatures getting to the mid 90’s and nighttime temperatures in the upper 70’s.  With the high temperatures, we are seeing an increase in insect and disease activity.   

Rice stink bug adult.

This week with the early rice starting to head we are seeing a large population of rice stink bugs.  In the verification field (with Dr. Saichuk) we were catching almost 1 stink bug per sweep.  Very high numbers are being reported throughout the parishes.   The rice stink bug is the second most important rice pest in Louisiana.  They overwinter as adults in grass clumps, ground trash and woods.  They emerge early in the spring and several generations can develop on grasses in and around rice fields.

As the rice begins heading, they move to the rice and begin feeding on the developing kernels.  Adult rice stink bugs are shield-shaped, metallic brown insects about one-half inch long.  Both nymphs and adults puncture the grain with their stylets and suck the juices.  Grain fed on in the early milk stage fail to develop normally and empty glumes or shriveled grain results.  Grains fed on in the dough stage may be weakened structurally and break in the filling process or if infected with a fungus, develop a black spot or pecky rice.  Damage can result in reduced yield, reduced milling quality and lower grade.

Rice stink bug first instar nymphs (photo by J. Saichuk).

Rice fields should be monitored weekly beginning immediately after pollination until kernels begin to harden.  Random sweep net samples should be taken in each field, and the total number of rice stink bugs collected should be recorded.  During the first two weeks of heading, fields where 30 or more stink bugs are taken per 100 sweeps should be treated.  In the later stages of heading, fields should be treated when 100 or more stink bugs are taken per 100 sweeps until two weeks before harvest.  Scout in the morning for best results.

Chemicals recommended for rice stink bug control in Louisiana includes:

Insecticide                                          Dosage Per Acre Active Ingredient

Penncap-M                                         .75 – .5 lbs A.I./Acre

ProAxis                                                .0125 – .02 lb A.I./Acre

Prolex                                                  .0125 – .02 lb A.I./Acre

Mustang Max                                     .0165 – .025 lb A.I./Acre

Malathion 57% EC                              .6 – .9 lb A.I./Acre

Sevin 805                                            1 1/4 – 1 7/8 lb product per acre

Sevin 4F                                              1 – 1 ½ qts. Product per acre

Methyl Parathion 4EC                                    3/4 lb. A.I./Acre

Karate Z                                              .025 – .04 lb. A.I./Acre

Declare                                                .0125 – .02 lb. A.I./Acre

 Remember, as always, follow label instructions.                                              

I am also seeing some grasshopper damage on the rice that is just heading.  The grasshoppers are feeding on the developing grain.  The kernels that are being fed on will abort and not fill.  Very rarely do we need to treat just for grasshoppers but if they are severe a treatment may be necessary.  All of the insecticides listed above except for Malathion and Sevin are labeled for grasshoppers, however; some of the rates are different.  Please be sure to read the label for the correct rates.

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