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rice strain fall armyworm on soybean

Rice-Grass Strain of Fall Armyworm in Soybeans

Rice-Grass Strain of Fall Armyworm in Soybeans published on 2 Comments on Rice-Grass Strain of Fall Armyworm in Soybeans

I have been receiving phone calls regarding fall armyworms moving into late planted soybeans.  Most of these calls come after a producer has applied a Round up application to control grasses that may have been missed with previous applications. Fall armyworms moving off of these grass hosts are the “grass or rice strain” armyworms preferring grass hosts over legumes.

rice strain fall armyworm on soybean
T    Rice Strain of Fall Armyworm in Soybeans: Photo by Gus Lorenz

The problem is often exaggerated by the size of fall armyworm larvae moving off of grass into soybeans with large, late, instar worms causing severe foliage loss in a short time period.  Many lepidopteran insects will consume more foliage in the last 3 to 4 days of development than throughout their entire life cycle as a caterpillar. This means that once the grass hosts have been removed by a herbicide application, soybeans can experience severe defoliation from migrating armyworms.

Thus, grassy fields should be scouted before an herbicide application is applied. If fall armyworms are found, a pyrethroid can be added to effectively control these insects before they move into beans.

If you have any questions or concerns please contact Sebe Brown or Dr. David Kerns for more information.

Sebe Brown         Cell: 318-498-1283        Office: 318-435-2903

Dr. David Kerns          Cell: 318-439-4844        Office: 318-435-2157

 

Sorghum midge damage Photo by LSU agcenter

Sorghum Midge in Northeast Louisiana Sorghum

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I have received a few phone calls regarding sorghum midge in Northeast Louisiana.  Sorghum midge is small insect (1/8 inch or smaller) that has dark wings and an orange body.  The sorghum midge is primarily found on grain sorghum and Johnson grass with both hosts playing an important role in overwintering and reproduction.  Adult midges will emerge in the spring and often complete two generations on Johnson grass before moving into grain sorghum.

Sorghum midge females may lay as many as 50 eggs in the flowering spikelets of sorghum with resulting damage occuring during bloom. The developing larvae feed on fertilized grain ovaries preventing kernel development. Affected sorghum heads will have blanked or irregular grain patterns. Early planted sorghum will often have lower populations of sorghum midge than later plantings. Promoting crop uniformity will also help reduce the instance and severity of sorghum midge.  Johnson grass should be destroyed in and around field borders with all crop residue destroyed after sorghum harvest.

Sorghum midge damage Photo by LSU agcenter
Sorghum midge damage: Photo by LSU Agcenter

Scouting for sorghum midge can be difficult, especially in windy conditions. Additionally, sorghum midge only attack flowering sorghum, which occurs during the morning. Scouting sorghum for midge after 1 pm is almost always ineffective.  Also, sorghum midge adults live only 1 day so each day is a new brood of midge. Thus, flowering sorghum should be scouted daily if possible, twice weekly at minimum. Because midge are weak flyers, infestations will typically begin along field borders and spread downwind from alternative hosts (Johnson grass).

Sorghum midge adult Photo by Jerry Lenhard
Sorghum midge adult:Photo by Jerry Lenhard

The simplest and most efficient way to scout for sorghum midges is to carefully inspect all sides of randomly selected flowering grain heads. Handle grain heads carefully during inspection to avoid disturbing adult sorghum midges, and counting the adults present. Other sampling methods can be used, such as placing a clear plastic bag or jar over the sorghum grain head to trap adults. Scouting should begin once the plants are averaging 25-30% bloom.

The threshold for sorghum midge in Louisiana is 1 or more midge per head. Because new unprotected blooms emerge every day, additional insecticide applications at 5-7 day intervals may be needed. There are a number of pyrethoids that are effective towards sorghum midge as well as Lorsban/chlorpyrifos and Lannate.

If you have any questions or concerns please contact Sebe Brown or Dr. David Kerns for more information.

Sebe Brown      Cell: 318-498-1283        Office: 318-435-2903

Dr. David Kerns        Cell: 318-439-4844         Office: 318-435-2157

Transform WG Section 18 Approval for Louisiana Cotton

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Transform WG Section 18 Approval for Cotton

Transform, a new insecticide containing the active ingredient sulfoxaflor, has received an emergency use exemption for SOME parishes in Louisiana for the control of tarnished plant bug in cotton. This product represents a new mode of action and has excellent activity on tarnished plant bug. It also provides excellent control of cotton aphids, but this pest is NOT included on the Section 18 label. Typical application rates will range from 1.5 – 2.0 oz of Transform WG per acre. There is a substantial limitation on the Section 18 label … a 360 day plant back restriction for all crops except cotton. It is likely that this restriction would be lifted if a full label is granted later this year, as expected. However, there is no guarantee that a full label will be granted prior to 2013. Strongly consider using this product only in fields where cotton will be grown year! The details quoted below are directly from the Section 18 label.

This Section 18 only applies to the following parishes in Louisiana: Avoyelles, Bossier, Caddo, Caldwell, Catahoula, Concordia, DeSoto, East Carroll, Evangeline, Franklin, Grant, LaSalle, Madison, Morehouse, Natchitoches, Ouachita, Pointe Coupee, Rapides, Red River, Richland, St. Landry, Tensas and West Carroll.

  • This Specific Exemption is effective June 24, 2012 through September 30, 2012.
  • The labeling must be in the possession of the user at the time of application.
  • Read the label affixed to the container for Transform WG insecticide before applying. Carefully follow all precautionary statements and applicable use directions.
  • Use of Transform WG according to this supplemental labeling is subject to all use precautions and limitations imposed by the label affixed to the container for Transform WG.

Rotational Crop Restrictions: The following rotational crops may be planted at intervals defined below following the final application of Transform WG at specified rates for a registered use. Crop Re-Planting Interval:

  • Cotton – no restrictions
  • All other food and feed crops – 360 days

Application Restrictions and Rates: This product cannot be used without a valid state-specific Section 18 label. The label must be in the possession of the user at the time of application. The Section 18 label can be obtained from state and/or county authorities where it is valid.

  • Do not apply within 14 days of harvest
  • Do not make applications less than 5 days apart
  • Do not make more than two applications per acre per crop
  • Do not make more than one application in pre-bloom cotton
  • Return any unopened, unused container of this unregistered product to the manufacturer or distributor, or dispose of it in accordance with Resource Conservation and Recovery Act regulations following the expiration of the emergency exemption
    • Transform WG may only be used on Louisiana cotton acres that have been previously treated with two consecutive applications of recommended registered insecticides and tarnished plant bug infestations in the insecticide-treated field has exceeded the treatment action threshold for this pest.

Environmental Hazards: Transform is highly toxic to bee. In order to protect managed bees, also native pollinators in the treatment area, avoid making application under conditions where uniform coverage cannot be obtained or where excessive drift may occur. Morning or late afternoon applications should be encouraged.  The LDAF shall notify commercial beekeepers in the treatment area in connection with this program.

Cotton Aphids in Louisiana Cotton

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by Sebe Brown, Dr. David Kerns, LSU AgCenter Entomologists,

Dr. John Kruse, Cotton and Feed Grain Specialist

Cotton aphids can be a persistent problem in Louisiana cotton throughout the growing season. The cotton aphid is considerably variable in size and color with adults and nymphs ranging from yellow to green to black with winged and wingless forms appearing in mixed populations throughout a field. Cotton aphids have piercing-sucking mouth parts that allow them to feed on the phloem of developing cotton plants. Phloem is primarily composed of carbohydrates and contains little amino acids requiring aphids to continuously feed to satisfy their amino acid requirements. As a result of constant feeding, aphids must excrete large amounts of waste termed “honey dew” that has a very high sugar content and facilitates the growth of sooty mold fungi. Large amounts of sooty mold can coat the surface of leaves blocking sunlight and interfering with photosynthesis. Honey dew, when deposited on open bolls, can also cause sticky cotton resulting in ginning problems.

Cotton aphids prefer cooler temperatures and outbreaks of this pest are often associated with cool snaps. They are most often considered a secondary pest because natural enemies such as green lacewings and lady beetles often keep populations below damaging levels. However, insecticide applications for other pests often remove many of these natural enemies allowing populations to rapidly increase. Pyrethroids are notorious for causing cotton aphid outbreaks due to natural enemy destruction. Cotton aphids are also controlled by a naturally occurring fungus Neozygites fresenii. Epizootics of this fungus often cause aphid populations to crash and remained suppressed for the duration of the season.

Cotton aphids can cause significant reductions in yield, especially if the cotton is stressed, i.e. water stressed or during boll filling. Under non-stressed conditions, treatments may be considered when populations approach 50 per leaf, but stressed cotton should be treated earlier. Although most outbreaks of cotton aphid are controlled by fungal epizootics, these may not occur soon enough to prevent yield loss. Adequate control of cotton aphids with insecticides can be difficult due to this pest’s biology.

Aphids reproduce parthenogenetically, this is where unmated females will give birth to live female offspring. These nymphs are born pregnant and will begin to reproduce in about 5 days. Thus, a population of 20 aphids per leaf can explode into hundreds per leaf in a matter of days. Insecticide resistance and rebounding populations can occur very quickly, with resistance to neonicotinoid insecticides becoming common. Cotton aphid infestations will typically begin in the terminal and quickly spread throughout the plant canopy with feeding primarily taking place on the underside of leaves. This behavior necessitates the use of a translaminar or systemic insecticide limiting the options producers have for control. Intruder tends to be one of the most commonly used insecticides for cotton aphid control, but do not use less than 1 oz per acre and the addition of MSO will often enhance control. If neonicotinoid insecticides fail to provide effective control, producers should switch to Carbine 50WP.

Tarnished Plant Bug

Tarnished Plant Bug Numbers Increasing

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With cotton moving along throughout North Louisiana, tarnished plant bugs have begun to migrate into fields.  As a result, Dr. Kerns and I been receiving more calls relating to TPB thresholds and treatments in early bloom cotton.

Tarnished plant bugs are ¼ inch long insects that vary in color from yellowish brown to green with black markings and a conspicuous triangle located on the dorsal (back) side.  Nymphs resemble the adults in general body shape and color but do not have wings.  Tarnished plant bugs damage cotton from pinhead square to final boll set.  Larger square damage affecting anthers, stigma, and styles can cause fertilization problems and fruit shed.

Tarnished Plant Bug
Tarnished Plant Bug: Photo by LSU AgCenter

The Louisiana threshold for bloom to harvest is 2-3 TPB per 5 ft of black drop cloth, 10 TPB per 100 or sweeps or 10% dirty squares.  Pre-bloom threshold levels are 10 -25 TPB per 100 sweeps.  Tarnished plant bugs are a difficult pest to control with constant insecticide rotation essential to attaining satisfactory control and prolonging the life of our current insecticide chemistries.  An initial application of imidacloprid, at high label rates, gives suppression of TPB. If cotton is beginning to bloom, an application of Diamond tank mixed with a neonicotinoid should be strongly considered. Diamond is an insect growth regulator and will not control adult TPB, an adulticide needs to be added in with the application to control adults.  Diamond has excellent activity on large nymphs while also causing egg sterility. Additionally, Diamond offers good residual activity and nymphal populations may be suppressed 7-14 days after application.

Once an initial Diamond application has been used, producers should rotate away from Diamond and  rely on its residual activity for eggs and hatching nymphs. However, producers should also target migrating adults with something that will offer good adult control. Insecticide choice at this time may likely be dictated by the presence of aphids, mites or bollworms. Diamond may be good for a follow up after this application.

If you have questions or concerns feel free to contact Dr. David Kerns or Sebe Brown for more information.

Dr. David Kerns                Cell: 318-439-4844                          Office: 318-435-2157

Sebe Brown                       Cell: 318-498-1283                          Office: 318-435-2903

Adult and Immature Chinch Bugs

Chinch Bugs in Late Corn and Grain Sorghum

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With the lack of rainfall in much of Louisiana, Dr. David Kerns and I have been receiving more calls regarding chinch bugs in late corn and grain sorghum. Chinch bugs are small insects 1/5 to 1/6 inch in length, with a black body and white front wings creating a white X when viewed from above. Immature chinch bugs resemble the adults only smaller and lacking wings.  Nymphs range in color from reddish brown to black in later instars.

Chinch bugs are typically active on grasses in and around fields and movement to seedling corn and grain sorghum is common. Damage by both adults and nymphs causes corn to have a reddish appearance on the stem and leaves.

Chinch Bug Damage in Grain Sorghum
Chinch Bug Damage in Grain Sorghum : Photo Courtesy of LSU AgCenter

Continued feeding can cause plants to wilt and eventually die.  Corn is most susceptible in the seedling stage when plant growth is slow and conditions are dry.  Seed treatments and soil insecticides will typically give an 18 day window of protection after emergence. However, during dry conditions water stressed plants are more susceptible to injury and seed treatments may not provide as long of protection as under adequate moisture conditions. Once plants have surpassed the most susceptible stage, chinch bug damage becomes less of an issue.

Adult and Immature Chinch Bugs
Adult and Immature Chinch Bugs: Photo Courtesy of Bart Drees TAMU Agrilife

If plant growth is slow and chinch bug numbers have reached 5 or more on 20% of plants 6 inches tall or less, a foliar rescue treatment should be applied to stop injury.

When using ground equipment, a high volume, high pressure sprayer delivering a minimum of 20 gpa should be used.  Aerial applications should only be used if ground equipment cannot make it across a field.

If you have any questions or concerns feel free to contact Dr. David Kerns or Sebe Brown for more information.

Dr. David Kerns                Cell: 318-439-4844                          Office: 318-435-2157

Sebe Brown                       Cell: 318-498-1283                          Office: 318-435-2903

Adult Spider Mites

Spider Mites Increasing in Cotton

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Dr. David Kerns and I have been receiving more phone calls regarding spider mites in cotton.  Mite problems are exacerbated by hot, dry weather and applications of broad-spectrum insecticides for early season pests. With little or no rainfall in many parts of the state, mite populations can increase rapidly.

Do not wait for spider mite treatments in early cotton if populations are found scattered throughout the field or if mites are moving in from field borders. When making applications, correct nozzles and high water volumes are essential for adequate coverage and application rates should reflect mite severity. Pyrethroid and acephate applications should be saved, if possible, to avoid flaring mite populations.

Adult Spider Mites
Adult Spider Mites: Photo by David Kerns

Acaricide application rates should be adjusted for population severity with higher rates used for more severe infestations; however, producers and consultants have been getting good results with abamectin at 6 oz/acre. Rates below 6 oz/ac are not recommended. Zeal has provided excellent control of mites in our region, but be aware that only 1.0 oz/acre of Zeal miticide can be applied per cropping season. Therefore it may be best to save your Zeal application for more critical situations.

If you have any questions or concerns, do not hesitate to contact Dr. David Kerns or Sebe Brown for more information.

Dr. David Kerns    Cell: 318-439-4844    Office: 318-435-2157

Sebe Brown     Cell: 318-498-1283      Office: 318-435-2903

Cotton Fleahopper Adult

Cotton Fleahopper Numbers Increasing

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Currently, Dr. David Kerns has been finding increasing numbers of cotton fleahoppers in cotton on the Macon Ridge Research Station. Fleahoppers are small, 1/8 inch, insects that have an oval shaped, elongated body. These insects are yellow to green and resemble other Hemipteran true bugs. They essentially look like a very small, green tarnished plant bug.

Cotton Fleahopper Adult
Cotton Fleahopper Adult. Photo by David Kerns

Cotton should be scouted for fleahoppers the first three weeks of squaring.  Detection can be difficult due to the flighty nature of these insects. Simply casting a shadow over the pest will often make them take flight. Louisiana pre-bloom thresholds for fleahoppers are 10 to 25 insects per 100 sweeps with adjusted pre-bloom treatment levels to maintain between 70 and 85% first position square retention.

However, scouting small cotton with a sweep net is difficult and produces questionable results.  Additionally, detecting small fleahopper nymphs in a sweep net is difficult as well.  A better technique is to simply examine the terminal of plants watching for adults taking flight and then examining the terminal very closely for small nymphs.  Morning is the best time to scout for fleahoppers and if the wind is blowing, they take shelter in the plant canopy.

Control of cotton fleahoppers can often be obtained with lower label rates of insecticides than rates used for other plant bug insect pests. Fleahoppers are typically fairly easy to control with insecticides.  Insecticides that are commonly used include Acephate at 4 oz/ac, Centric at 1.5 oz/ac and Bidrin at 3.2 fl-oz/ac.

If you have any questions or concerns feel free to contact Dr. David Kerns or Sebe Brown for more information.

Dr. David Kerns    Cell: 318-439-4844    Office: 318-435-2157          Sebe Brown     Cell: 318-498-1283      Office: 318-435-2903

Section 18 approved for Tenchu 20SG to control rice stink bugs in Louisiana – 2012 season

Section 18 approved for Tenchu 20SG to control rice stink bugs in Louisiana – 2012 season published on No Comments on Section 18 approved for Tenchu 20SG to control rice stink bugs in Louisiana – 2012 season

This blog was originally post at the Louisiana rice insects blog.

A Section 18 request has been approved by EPA for the use of Tenchu 20SG on up to 100,000 acres of Louisiana rice to control rice stink bugs. Click here to read about biology and management of rice stink bugs. This product will provide an alternative mode of action to the pyrethroids that are currently registered for use in Louisiana. The exemption expires October 31, 2012. The distributor in Louisiana is Mr. Michael Hensgens with G&H in Crowley. According to Mr. Hensgens, the suggested retail price is $24.30 lb at ½#per acre = $12.15/ac.

Rate and restrictions: Please contact your local County Agent for a copy of the Section 18 registration before using this product. Remember that the label is the law! The registered rate is from 7.5 to 10.5 oz of product per acre. A maximum of two applications can be made per acre per season. A seven day pre-harvest interval must be observed. Be aware that this product is toxic to honeybees – read the Section 18 registration for precautions to avoid bee injury.

Treatment threshold:We do not recommend treating until you exceed the recommended thresholds as described on the Section 18 label (the current label reads that you should follow the Texas guideline – this has been amended to reflect LSU AgCenter recommendations in pub 2270). 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 and then treat if they exceed the threshold as described in LSU AgCenter Publication 2270. During the first two weeks of heading, treat when there are 30 or more stink bugs per 100 sweeps. From the dough stage until 2 weeks before harvest, treat fields when there are 100 stink bugs per 100 sweeps.

Before we consider applying for an emergency exemption next field season (should we feel it is warranted) we need to gather some specific data. We need your assistance gathering this information.

1. Resistance. Please notify us if you believe that you have a stink bug population that is resistant to pyrethoids. We will gather insect samples to run laboratory bioassays to screen for insecticide resistance.

2. Efficacy. If you use Tenchu 20SG we would appreciate any data you gather on residual efficacy of the product. Data from Texas has indicated that it provides a longer window of activity than pyrethoids. This will potentially result in a reduction of the number of insecticide applications to a field in one season. We will be conducting efficacy trials in Louisiana to measure residual efficacy when compared to pyrethoids. If you’d like to participate in a field demo, please contact your local County Agent and they can work with me to make arrangements.

3. Milling. We also need your assistance in gathering data on milling quality of rice. Specifically, we need more data on reductions taken at the mill in the form of peck and broken grains which is attributed to Rice stink bug feeding injury. Any information you can provide on grade reductions attributed to rice stink bug feeding injury will be appreciated.

For more information, please contact Natalie Hummel, Associate Professor, LSU AgCenter at nhummel@agcenter.lsu.edu or 225-223-3373.

Insecticide Seed Treatments and Early Season Insects in Soybeans

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Thrips Damage to Soybeans (Photo by Angus Catchot)Girdled Soybean Stems from Threecornerd Alfalfa Hoppers. Photo by David AdamsColaspis Beetle Photo by Natalie HummelBean Leaf Beetle Damage to Soybeans Photo by Lee Jenkins

by Sebe Brown, Dr. David Kerns, Dr. Rogers Leonard LSU AgCenter Entomologists, Dr. Ronnie Levy, Soybean Specialist

 Soybeans are affected by a number of insect pests from emergence to harvest in Louisiana. Damage by these pests can cause reduced stand, foliage damage, stem girdling, and ultimately yield losses if extensive injury is incurred early in soybean seedling development.

 With most soybean production practices involving some level of reduced tillage, soil dwelling insects have a favorable environment for overwintering and reproduction. Increased production costs and high soybean prices have made getting the soybean crop off to a healthy start an important consideration for growers. Planting in late March to early April exposes seedling soybeans to cool weather that can stall plant growth and increase susceptibility to insect pests. Actively growing plants can sustain considerable insect populations without any evidence of injury.  Insecticide seed treatments (ISTs) have been documented to help control threecornered alfalfa hoppers, colaspis, thrips and suppress bean leaf beetles in seedling soybeans.

 During dry weather conditions, when soybeans grow slowly, thrips populations can build to damaging levels and occasionally cause significant injury with some seedling mortality. Plant stress caused by herbicide injury can compound thrips injury causing plants to appear very poor. However, thrips rarely justify the use of an overspray except in cases where severe stand loss and defoliation are a possibility.

Threecornered alfalfa hoppers are small, wedge-shaped insects that damage young soybeans by puncturing the main stem resulting in a girdle near the soil surface. Girdling in soybeans 12 to 15 inches in height will result in some stand loss but rarely reduces yield. Early season damage in often compensated for by adjacent plants.

Colaspis beetles are small, oval shaped insects that can injury soybean roots as larvae and defoliate leaf tissue as adults. Larvae appear as small c-shaped grubs that can be found near the soil surface. Colaspis beetles rarely contribute to any appreciable damage; however, with large populations of larvae consuming lateral roots and soft portions of underground stems soybean plants may exhibit symptoms similar to nematode infestations.

 Bean leaf beetles are small, (1/5 inch) in length, insects that are characterized by four large quadrangular markings on the elytra (wing covers) with a black triangle located centrally on the thorax behind the head.  Bean leaf beetles overwinter in litter adjacent to soybean fields and damage to emerging seedlings can be extensive. Adult damage is characterized by round holes chewed into new leaves and the transmission of bean pod mottle virus is also a concern.

 Producers have a variety of options with regard soybean ISTs. Monsanto and Pioneer’s base IST package utilizes imidacloprid with an upgrade to Poncho (clothianidin)/Votivo upon request. Syngenta’s Avicta Complete Beans and CruiserMaxx soybeans utilize thiamethoxam for the IST and Valent’s Inovate is based around clothianidin.

 Research from the Mid-South has demonstrated an average yield increase of 3.5 bu/a with ISTs; while early season soybeans resulted in a 6 bu/a average increase in yield.

 ISTs are effective in suppressing bean leaf beetles and controlling a number of early season soybean insect pests including thrips, colaspis and threecornered alfalfa hopper. ISTs are one of the BMPs recommended by the LSU AgCenter for soybean integrated pest management.

 For more information concerning insect pest management, contact your local LSU AgCenter parish agent, LSU AgCenter specialist, or Louisiana independent agricultural consultant.