The Cotton Foundation
 
PEST/DISEASE MANAGEMENT
 
 

Developing Dynamic Action Levels During Flowering for Control of Tarnished Plant Bug in Cotton With Insecticides

Previous work in this ongoing project at the Louisiana State University AgCenter suggests that squares should be examined on fruiting branches located between plant main stem nodes four and seven from the plant terminal. Another series of studies found tarnished plant bug nymphs consistently preferred squares above other reproductive structures during the flowering and boll maturation stages of plant development.

In 2007 tests, researchers found that an action threshold of 10-20 percent squares with feeding evidence could be effective in reducing insecticide applications targeting tarnished plant bug without sacrificing cotton yield.

Scientists will continue to relate squares (flower bud) injury to cotton yield losses during discrete flowering periods. Current and new classes of insecticides will continue to be evaluated for their effectiveness using square injury and insect density. These results will support the efforts of the Mid-South entomologists in establishing effective triggers for tarnished plant bug management with new insecticide chemistries.

 
Glyphosate-Resistant Palmer Amaranth Screen and Management in Arkansas and Tennessee

University of Tennessee and University of Arkansas scientists continue to work with farmers and county extension agents who have identified Palmer pigweed they feel is glyphosate-resistant and examine random Palmer populations in cotton for their overall sensitivity level to glyphosate. Field and greenhouse experiments have identified two very distinct responses to glyphosate.

This project’s objectives are to: 1) identify new glyphosate-resistant Palmer biotypes 2) examine management strategies to control confirmed glyphosate-resistant Palmer pigweed and then 3) educate producers on best management practices to control this weed.

 
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Spider mites are transferred onto cotton by stapling green bean leaves, which are infested with mites, onto the cotton plant’s cotyledons.

Spider Mite Management: Identification of Wild Hosts and Their Role in Seasonal Population Growth of the Spider Mites

In this ongoing effort, a Mississippi State University doctoral student is determining which weeds are major hosts of spider mites in the Mississippi Delta and how they contribute to seasonal population increases of spider mites.This research will be conducted over multiple years and will address several issues in mite management. Initially, a comprehensive host list will be developed and determinations made on how these plants contribute to spider mite population increases in cotton over the season.

In 2007, several important hosts of the two-spotted (TSSM) spider mite were identified. Henbit is proving to be the most common host and the TSSM is remaining active and reproducing throughout the winter on that weed. Researchers also observed that Brazilian verbane, cutleaf evening primrose and several other weeds served as hosts – along with corn which they suspect could contribute to late-season mites’ population growth.

Other southern states also experienced increases in mite densities, well above those seen in previous years. It is probable that spider mite management will continue to be a frequent cost of cotton production in southern states so effective management of the pest will be very valuable.

 

Susceptibility of Southwestern Pink Bollworm to Bt Toxins


A program to eradicate pink bollworm from the Southwest is based foremost on high levels of use of Bt cotton. It also utilizes the complementary technologies of pheromone-based mating disruption, releases of sterile pink bollworms and limited use of conventional insecticides. It is particularly critical at this time that the susceptibility of pink bollworm to Bt toxins be documented both in and out of the eradication zones.

 

In 2007, University of Arizona researchers established pink bollworm strains from nine sites in the southwestern United States and completed bioassays for seven with the other two in progress. To date, no survivors have been found at diagnostic concentrations of 10 micrograms Cry1Ac or Cry2Ab per ml. diet. Numbers tested to date are ca. 2200 for Cry1Ac and 1000 for Cry2Ab.

 

The will now use bioassays to test for susceptibility to Bt toxins Cry1Ac and Cry2Ab of pink bollworm strains derived from cotton fields in 2008.


 

Pink Bollworm Eradication Technical Support, Systems Development, Program Evaluation and Onsite Support

This ongoing project is providing an expert to give much-needed technical support for the Pink Bollworm Eradication Program in such areas as major pheromone system development, sterile insect control system and program evaluation, execution and quality control.

Among key activities in 2007-2008 were: providing leadership/advice to the principle grower leadership and find workable options which would facilitate program expansion into Yuma, AZ, and the Mexicali, Mexico area; helping provide a coordinated and organized set of possible field tests to test the best new formulation of pheromone disruptant for the program; conducting a meeting of key field and rearing facility program managers involved in daily sterile moth handling to address moth quality concerns; reviewing the entire Chihuahua program during a 1,200-plus mile field trip; and helping temper “nationalistic” prejudices with U.S. and Mexican personnel when problems arose in fields adjacent to the Rio Grande/Rio Bravo River.

With the eradication program again increasing in both the United States and Mexico, the principal investigator/consultant will continue to provide support throughout the 2009 growing season. EffortPink Bollworm Eradication Technical Support, Systems Development, Program Evaluation and Onsite Supports also will be focused on ensuring that sterile moths are used as effectively as possible.

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The susceptibility of pink bollworm to Bt toxins is being documented both in and out of the eradication zones.

 
Use of Hyperspectral Imagery and Soil Electrical Conductivity for Site-Specific Reniform Nematode Evaluations and Economical Management

The reniform nematode is rapidly spreading across the Cotton Belt’s southeast region and has become the most economically serious cotton pest in Alabama, Louisiana and Mississippi  -- where this ongoing project is being conducted. The target is to increase the effectiveness of nematicide applications using a combination of methods to improve the prediction of economic damage resulting from the nematode and to maximize an economic yield response.

To implement a successful reniform management program, producers must first identify that the nematode is present in a field and determine populations present in each location. In Mississippi, remotely sensed hyperspectral imagery has been correlated with reniform nematode population levels to obtain an accurate estimation of the infield nematode distribution without taking a soil sample. Alabama is working with the Greenseeker technology.

Merging technologies can provide information for maximizing reniform management options and preserving cotton yields. Resulting data will be applicable to other regions where the reniform is becoming a problem.

Analysis on the data collected from the selected infested fields and was begun in 2007 and continued in 2008. Yield data from all plots will be collected in 2008 and analyzed prior to reporting the information at state and national meetings and publishing in various scientific, Extension and popular journals.

The specific objectives are: 1) determining the accuracy of estimating reniform nematode numbers based on remote sensing reflectance data to provide an economical means of predicting nematode numbers without soil sampling, 2) evaluating the effectiveness of nematicides for reniform nematode management as influenced by soil electrical conductivity (EC) zones and 3) correlating the utility of these techniques in combination with real-time NDVI for predicting nematode numbers in specific EC zones to optimize nematicide use and maximize yields.

 

Introgression of Reniform Nematode Resistance

Reniform nematode has been detected in at least 187 counties and parishes of the southeastern United States. In this new project, researchers are working to identify cotton plants with the resistant gene with the aim of releasing reniform resistant breeding lines adapted to the Mid-South.

Specific objectives include: 1) transfer reniform nematode immunity/resistance from the LONREN-1 cotton line into six Mid-South Upland breeding lines via conventional plant breeding protocols; 2) use marker-assisted selection (public domain marker BNL 3279) to identify reniform immune plants within segregating populations; 3) evaluate reniform immune breeding lines for yield, fiber quality and areas of adaptation; and 4) release high yielding, high quality reniform immune breeding lines adapted to the Mid-South cotton production region.

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The reniform nematode has increasingly infected cotton across the Belt over the past decade.

 
Developing Sensor-Based Technology for Remote Detection of Stink Bugs in Cotton

Sucking bugs have become a major problem in current Bt cotton varieties because of reductions in insecticides that provided coincidental control of these bugs. Stink bug control costs have escalated in particular, especially in the Southeast. In fact, in a 2002 survey by the South Carolina Cotton Board, producers ranked stink bug as number one out of 60 production problems.

Clemson University scientists are 1) evaluating volatile emissions from stink bugs and cotton bolls injured by stink bugs and 2) developing/refining chemical and/or physical sensor tools for growers and consultants to improve management decisions and enable site-specific insecticide applications.

 
Establishing a Boll Weevil Population Monitoring Program for the U.S. Cotton Belt

The boll weevil has been functionally eradicated from most Cotton Belt regions but some areas have been re-infested -- with the origin always impossible to determine.

In this new project, USDA Agricultural Research Service scientists will try to determine if a library of baseline population patterns can be identified and maintained at the USDA-ARS station in Weslaco, Texas. The ultimate goal is to provide a service of identifying the origin of boll weevils collected from previously eradicated zones to help identify sources of re-introduction. They will use a state-of-the-art molecular technique developed specifically for this origin determination.



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