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Adult Spider Mites

Spider Mites Increasing in Cotton

Spider Mites Increasing in Cotton published on No Comments on Spider Mites Increasing in Cotton

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

Western Flower Thrips

Western Flower Thrips in Cotton

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Currently, Dr. David Kerns has been finding large numbers of western flower thrips in cotton trials located on the Macon Ridge Research Station. Western flower thrips were a problem in Louisiana cotton last year and it appears that this trend will continue for the 2012 season.

Western flower thrips are more difficult to control than other thrips species found in cotton. Insecticide seed treatments offer 10-14 days of control after plants emerge and western flower thrips can cause these treatments to give out sooner. The use of acephate, dimethoate, bidrin etc. will not give satisfactory control of established western flower thrips populations and will likely flare spider mites and cotton aphids.

Western Flower Thrips
Western Flower Thrips. Photo by David Kerns

LSU AgCenter research has demonstrated that Radiant, when used with an adjuvant, effectively controlled all species of thrips including western flower thrips in seedling cotton.  Radiant effectively kept thrips populations controlled for 7 days after application and did not flare spider mites or aphids.

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

For more information on early season thrips management in cotton please see the link below.

http://louisianacrops.com/2012/04/09/early-season-thrips-management-strategies-in-cotton/

Western Flower Thrips Photo courtesy of UC IPM and Jack Kelly Clark

Early Season Thrips Management Strategies in Cotton

Early Season Thrips Management Strategies in Cotton published on No Comments on Early Season Thrips Management Strategies in Cotton

By Sebe Brown, Dr. David Kerns, Dr. Rogers Leonard – LSU AgCenter Entomologists

Thrips are annual pests of cotton in Louisiana. Damage by these insects cause stunted growth, delayed plant maturity and plant death under heavy infestations.  Cotton is most susceptible to thrips from emergence to the 4 true leaf stage.  Once cotton has reached the 4 true leaf stage, root differentiation has increased, terminal bud growth is accelerated and plants become less susceptible to injury.

The most common thrips found in Louisiana cotton are tobacco thrips, eastern flower thrips, onion thrips and western flower thrips.  These insects overwinter on a variety of weed hosts.  Planting seasons with windy conditions can have considerable influence on the severity of thrips populations in early cotton.  Thrips are typically weak flyers and wind helps to distribute infestations across fields.

Cotton seedlings that experience cool, wet soils develop very slowly and remain susceptible to thrips injury much longer than cotton planted in a warmer, more optimum, environment.  This year has been very warm and wet with considerable alternate hosts around cotton fields to produce sources of thrips infestations.  With the loss of Temik for the 2012 growing season, insecticide seed treatments (ISTs) and over-sprays will be critically important for controlling thrips on seedling cotton.

Cotton seed comes with a variety of seed treatment options that may either be purchased through a seed company or applied by a dealer downstream.  Outlined below are a few of my thoughts with regards to insecticide seed treatment packages on cotton seed.

Dow’s Phytogen seed comes with a base package of thiamethoxam (Cruiser), with Avicta Complete Cotton available upon request.  Avicta Complete Cotton includes Cruiser for the IST, multiple fungicides and abamectin for nematode control.  Information on Phytogen seed treatment options can be found here.

http://www.dowagro.com/phytogen/varieties/seed_treatments.htm

Monsanto’s Deltapine cotton seed comes with a combination of products that fall within the Acceleron treatment umbrella. The base package in cotton includes imidacloprid (Gaucho) and several fungicides.  However there are several options within the Accereleron brand.  Be sure that your seed is treated with what was ordered.  These options are upgrades to Avicta Duo Cotton with Cruiser for insect control, several fungicides for disease control and abamectin for nematodes.  Beware: the Acceleron seed treatment label in other crops may contain other products.  More information on Acceleron seed treatment options can be found here.

https://www.acceleronsts.com/Cotton/Pages/Cotton.aspx

Bayer’s Stoneville/Fibermax cotton seed comes with a base package that includes Gaucho for insect control and thiodicarb for nematodes that falls under the Aeris treatment umbrella.  Producers also have the option to upgrade to Poncho/Votivo with clothianidin (Poncho) for insects and Bacillus firmus (Votivo) for nematodes. More information on Aeris seed treatment options can be found here.

http://www.bayercropscience.us/products/seed-treatments/aeris/

Western Flower Thrips Photo courtesy of UC IPM and Jack Kelly Clark
Western Flower Thrips Photo courtesy of UC IPM and Jack Kelly Clark

Another option is to buy the minimum insecticide treatment available, and have a dealer apply additional insecticides downstream after the seed is purchased.

IST’s offer limited early season protection from thrips. Effective residual efficacy usually offers 10-14 days of control after plants emerge. Unsatisfactory residual control can occur with these treatments and cotton should be frequently scouted for thrips until the four leaf stage and when cotton plants are actively growing.

During 2011, western flower thrips were a problem in many Louisiana cotton fields. Western flower thrips can be difficult to control with standard applications of acephate, dimethoate, bidrin, etc.  Producers also risk flaring spider mites and cotton aphids with repeated applications of broad-spectrum insecticides. Recent research conducted by the LSU AgCenter demonstrated satisfactory control of a complex of species including western flower thrips with Tracer and Radiant at 2 and 7 days after treatment.

The use of a nonionic surfactant with these insecticides can help increase efficacy against thrips. Rescue applications of foliar insecticides should be applied early in cotton development with applications at the 1-2 true leaf stage yielding significantly greater lint per acre than treatments applied at the 3-4 true leaf stage.  Do not wait for thrips treatment in an attempt to time an overtop herbicide application.

Insecticide seed treatment options get producers off to a good start when it comes to insect pest management in cotton. However, these treatments should not be relied upon for sole control of all early season pests. IST’s are one of the best management practices (BMP’s) recommended by the LSU AgCenter for cotton IPM.

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

Thrips-injured cotton. Photo: LSU AgCenter
Thrips-injured cotton. Photo: LSU AgCenter
Cotton without thrips injury. Photo: LSU AgCenter
Cotton without thrips injury. Photo: LSU AgCenterThrips-injured cotton. Photo: LSU AgCenter

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