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Wheat Insect Update

Wheat Insect Update published on No Comments on Wheat Insect Update

by Sebe Brown, Extension Entomologist

All, I have been seeing more instances of true armyworms infesting wheat in the North Louisiana.  These include wheat plots at St. Joe and Winnsboro at various stages of growth.  Our threshold for armyworms is 5 worms per square foot with foliage loss occurring. If armyworms reach the flag leaf and the wheat has not headed an application should be made.  I have also encountered varying levels of stink bugs (primarily rice stink bug) in wheat. Populations of stink bugs have to be high for damage to occur and our threshold is 10% infested wheat heads in the milk stage and 25% infested heads in the soft dough stage.  Stink bug numbers  will usually be higher around the edges of a field with numbers falling off as you walk further toward the middle. This means you may reach threshold around the edges of a field, but may also be well below threshold 100 feet in.  Applications of pyrethroids can control both of these pests.

Rice stink bug  photo courtesy of Gus Lorenz

Armyworm larvae on wheat heads photo courtesy of Robert Bellm, University of Illinois Extension

 

 

Rice insecticide seed treatment considerations for 2012

Rice insecticide seed treatment considerations for 2012 published on No Comments on Rice insecticide seed treatment considerations for 2012

by Natalie Hummel

You can link to Dr. Natalie Hummel’s weblog by going to: http://louisianariceinsects.wordpress.com/

This article was originally published in Louisiana Farm and Ranch, February 2012. I’m reposting it here for your information. This is an important article to read as growers are making their decision about insecticide seed treatments in rice for the 2012 season.

Authors: Natalie Hummel, Associate Professor and Assistant to the Director & Mike Stout, Professor

We have had quite a few inquiries about using a combination of seed treatments, neonicotinoid and Dermacor X-100, in rice. While this practice is legal, using more than one seed treatment is not a practice that we encourage in most circumstances because it results in more insecticide use in rice production than may be necessary.

The rice industry is considering one of these combinations of seed treatments: 1) Dermacor X-100 and CruiserMaxx or 2) Dermacor X-100 and NipsitINSIDE. Typically, a combination of seed treatments is only being considered when planting rice at low seeding rates, primarily because of concerns about the lack of efficacy of CruiserMaxx and NipsitINSIDE at hybrid seeding rates (25 lbs/acre or less) that we have observed in our rice water weevil demonstration trials and small plot trials. The second scenario is where Dermacor X-100 is being used for rice water weevil management and there is a history of stand reduction because of a sporadic pest infestation, usually chinch bugs or armyworms. Combining seed treatments provides a benefit of protecting the crop from injury by some primary and sporadic crop pests.

As the rice industry moves toward a more sustainable crop production profile, the LSU AgCenter strongly encourages rice producers to be good stewards of these insecticide seed treatments. Stewardship of these seed treatments means avoiding the use of insecticides not needed in the crop. For this reason, we discourage the widespread use of a combination of insecticide seed treatments in rice. We instead encourage the person making the seed treatment decision to consider the spectrum of pests that each insecticide can control, the seeding rate, and the history of crop pests in that field.

It is important to remember that each of the seed treatments controls a different group of insects. Dermacor X-100 belongs to a class of insecticides called anthranilic diamides, which target a specific receptor in the muscle of the insect. Dermacor X-100 is registered to control rice water weevil larvae, borers (Mexican rice borer, Rice stalk borer, Sugarcane borer), armyworms and colaspis (2ee registration for suppression). CruiserMaxx and NipsitINSIDE are both neonicotinoid insecticides that affect the nervous system of target insects. CruiserMaxx is labeled to control rice water weevils (larvae and adults), chinch bugs, colaspis and thrips. NipsitINSIDE is labeled to control rice water weevils and colaspis. We do not have data to support the ability of CruiserMaxx or NipsitINSIDE to control chinch bugs, colaspis or thrips in Louisiana, but we anticipate that they will control these pests based on observations from other crops and from rice in other parts of the world. As you study these seed treatments, you can see how a combination of these products can control most of the insects that attack rice in Louisiana. This is part of the reason why there is an inclination toward using a combination of treatments.

Here are criteria for you to consider as you make your seed treatment decision. The first is the seeding rate. This needs to be considered because neonicotinoids don’t always provide good control of rice water weevils at low seeding rates. Dermacor X-100 does provide control of rice water weevils at all seeding rates, but it will not control chinch bugs or thrips. According to the chemical manufacturers, neonicotinoids do control other early season pests including chinch bugs, thrips and colaspis. Another challenge at low seeding rates is that the plant stand is thin and is less tolerant to any insects that reduce the stand by killing seedlings. Insects that can reduce the plant stand count include armyworms, chinch bugs, colaspis and thrips. Borers can infest fields after the plant is at the green ring growth stage and reduce yields by causing deadhearts and whiteheads. Remember that if you put out a combination of seed treatments for a sporadic pest and that pest doesn’t infest your field, then you didn’t need to use a combination of seed treatments. We have data that indicate that rice water weevils infest more than 90% of rice fields in Louisiana. This justifies the use of a seed treatment to control rice water weevils as part of a good IPM program. That is not the case for many of our sporadic pests (armyworms, chinch bugs, colaspis, borers, etc.), which rarely occur at levels that justify treatment. Also, keep in mind that we rarely recommend an insecticide treatment for thrips in rice; usually the damage is not severe enough to require an insecticide.

Here are a couple of situations where a combination of seed treatments may be a good management decision. If you are planting rice at a low seeding rate and you anticipate that you will have an infestation of chinch bugs that would justify a pyrethroid treatment, then a combination of seed treatments would be a good option. In this situation, you would be using Dermacor X-100 to control rice water weevils, borers and armyworms and adding a neonicotinoid to control chinch bugs or thrips. Also, if you are planting rice at conventional seeding rates and you are using a neonicotinoid seed treatment to control rice water weevils and colaspis, but you typically have problems with armyworms or borers, then you may want to apply Dermacor X-100 to your seed.

There is one more thing to consider as you make your seed treatment decisions for the 2012 season. The EPA recently approved a Section 24C (special local need) registration for use of Dermacor X-100 in water-seeded rice. If you are interested in this option, a certified seed treater can provide more information. Remember that you CANNOT use the other seed treatments (CruiserMaxx or NipsitINSIDE) in water-seeded rice. The use of CruiserMaxx and NipsitINSIDE in water-seeded rice is illegal and will not provide control of the target pests.

If you have any questions about the seed treatment options registered for use in rice, please contact your local County Agent, or Natalie Hummel (nhummel@agcenter.lsu.edu) for more information.

 

Corn Insecticide Seed Treatment Options

Corn Insecticide Seed Treatment Options published on No Comments on Corn Insecticide Seed Treatment Options

Sebe Brown, Extension Entomologist

 Selecting corn seed treatments can be a challenging and expensive undertaking faced by many producers across Louisiana.  Corn seed treatments target three spectrums of pests: nematodes, fungal seedling diseases and insects.  This article will address insecticide seed treatment options available for corn.

Insecticide seed treatments are usually the main component of a seed treatment package.  Most corn seed available today comes with a base package that includes a fungicide and insecticide.  The insecticide options for seed treatments include Poncho (clothianidin), Cruiser/Cruiser Extreme (thiamethoxam) and Gaucho (Imidacloprid).  All three of these products are neonicotinoid chemistries.  Cruiser and Poncho at the 250 (.25 mg AI/seed) rate are the most common base options available for corn.  These insecticides are a good foundation; however, do not expect these treatments to give you extended protection from all below ground pests. If sugarcane beetles have been a problem in the past, Cruiser at the 250 or 500 rate will not provide adequate control; consider using Poncho at the 500 rate with 1250 providing better protection.  None of these products provide adequate control of cutworms.  Each company offers treatments that provide differing levels of early season insect protection, outlined below are some options available to producers with regards to insecticide seed treatments.

Pioneer’s base insecticide seed treatment package consists of Cruiser 250 with Poncho/Votivo 1250 available upon request.  Votivo is a biological agent that protects against nematodes.

Monsanto’s products including corn, soybeans and cotton fall under the Acceleron treatment umbrella.  Dekalb corn seed comes standard with Poncho 250.  Producers also have the option to upgrade to Poncho/Votivo, with Poncho applied at the 500 rate.

Agrisure, Golden Harvest and Garst have a base package with a fungicide and Cruiser 250.  Avicta complete corn is also available; this includes Cruiser 500, fungicide, and nematode protection.

Another option is to buy the minimum insecticide treatment available, and have a dealer treat the seed downstream.

Avipel was re-issued a section 18 for field and sweet corn seed in Louisiana.  The exemption is effective from February 24, 2012 through February 24, 2013.  Avipel can only be applied at the dealer and is used as a humane bird repellent.

It is important to note that below ground Bt traits available for western corn rootworm will not work on our strain of root worm in Louisiana.  Look at using in-furrow applications of Counter (organophosphate) or Force (pyrethroid) to help keep rootworms under control.  If an ALS herbicide was used in burndown applications or is anticipated, organophosphate insecticides should not be used.

Insecticide seed treatments are a valuable tool that allows producers a head start on early season protection from a variety of pests.  Minimizing damage below ground will help get this year’s corn crop off to a promising start.

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