IN THIS ISSUE

· TPMA Website
· Cotton Insect Situation
· Stink Bugs
· Tarnished Plant Bugs (Lygus) and Creontiades
· 2001 Cotton Varieties
· South Texas/Winter Garden BWEP Trap Line

TPMA Website

This newsletter as well as other Extension IPM newsletters from across the state can be viewed at the Texas Pest Management Association website at www.tpma.org.

These newsletters are a cooperative effort of the Texas Pest Management Association, Texas Agricultural Extension Service and the Texas A&M University Department of Entomology.

Cotton Insect Situation

Cotton maturity ranges from the third week of bloom through three weeks past cutout in the Tri-County area of Wharton, Jackson and Matagorda counties. Bollworm and budworm numbers have increased during the past week to ten days in Matagorda and Wharton Counties. At this time, a significant percentage of larvae that are found appear to be budworm. Boll weevil numbers and punctured square counts during the past week to ten days haven risen in parts of all three counties.

In Jackson County, aphid numbers were light and boll weevil punctured square counts ranged from 0 to 3%. Higher boll weevil punctured square counts can be found in some fields along their margins and borders. Bollworm/budworm egg, larvae and damaged square counts were 0 to 4%, 0 to 2%, and 0 to 1.5%, respectively.

Stink bugs were found in over 60% of fields that were monitored during the past week. Loopers, salt-marsh caterpillar and beet armyworms were found in low numbers in approximately 10% of the fields.

In Matagorda County, aphid numbers were light and boll weevil punctured square counts averaged 9.9% while individual fields ranged from 0 to 30%. Bollworm/budworm egg, larvae and damaged square counts averaged 1.13%, 5.10% and 5%, respectively. Individual field counts for egg, larvae and damaged square counts ranged from 0 to 6%, 2 to 16%, and 0 to 24%, respectively.

Also, stink bugs were found in 30% of the fields that were monitored during the past week. Salt-marsh caterpillars were found in 60% of the fields, while looper, creontiades and lygus were found in 20 to 30% of the fields as well.

In Wharton County, aphid numbers were light and boll weevil punctured square counts ranged from 0 to 6% in the fields that were monitored. Bollworm/budworm egg, larvae, and damaged square counts averaged 2.39%, 2.59% and 2.38%, respectively. Individual field counts for egg, larvae and damaged square counts ranged from 0 to 7%, 0 to 11%, and 0 to 8%, respectively.

Stink bugs, lygus, creontiades and salt-marsh caterpillars were found in 30% of the fields that were monitored during the past week.

Stink Bug Tests

Brown stink bugs and Southern green stink bugs are being found in cotton fields. So far, brown stink bugs seem to be the most prevalent in cotton fields at this time. Feeding on bolls may cause boll shed and/or seed damage, lint staining and yield reductions. Stink bugs can damage bolls that are less than 18-19 days old or have not reached 350 heat units. To determine if an insecticide application is warranted, examine 6 row feet of cotton in several locations in the field. When there is an average of one or more stink bugs per 6 feet of row, feeding can cause a reduction of economic returns. Stink bugs often are clumped near field margins. Second through fifth instar stink bug nymphs and adults can damage bolls. Fourth and fifth instars can cause the same level of damage as adults.

The following three tables summarize the work that was done in 2000 on the Glenn Emshoff farm in determining how much damage can be done to different age bolls by the brown stink bug.

Table four compares the percent control of different insecticides on the brown stink bug at three days after treatment. This work was done by Dr. Jeremy Greene from the University of Georgia.

Table 1. Damage caused by adult brown stink bugs caged on 4 days with bolls of different ages.

Tarnished Plant Bug (Lygus) Tests

At this time, blooms and young bolls are susceptible to tarnished plant bug feeding injury. Heavy feeding causes abnormal petal development and can result in crinkled and cupped blooms. Deep probing and feeding by these piercing and sucking insects causes internal damage on the anthers and stamens. Small bolls often exhibit black sunken lesions and may become desiccated and abort from the plant.

An insecticide treatment is warranted when 15 to 20 tarnished plant bugs per 100 plants is found. This same threshold should also be used for Creontiades. These plant bugs can cause small bolls up to 8 days old to be shed. They can cause a yield reduction in bolls that are less than 14 days old.

The following information in Table five is the summary of two tests that were conducted by Burris and Leonard who are researchers for the Louisiana State University. This work was conducted in northeast Louisiana.

2001 Cotton Varieties

The information in the table below list the cotton varieties that were planted as well as the percentage of acres of each variety accounted for in the territory of the Corpus Christi Classing office.

This information was compiled by T.J. Proske, Area Director for the USDA Marketing Service at Corpus Christi.

South Texas/Winter Garden BWEP Trap Line

Each year a 40 mile boll weevil trap line is monitored by the Boll Weevil Eradication Program. The trap line begins in Victoria County and continues through Jackson and Matagorda Counties. The traps begin below Placedo in Victoria county and proceeds to Vanderbilt and LaWard in Jackson County and continues on up to near Blessing which is located in Matagorda County. The first ten miles or the first ten traps are located in Victoria County which is located in the South Texas/Winter Garden zone of the BWEP.