Northwest Plains
Pest Management News
Volume 1 Issue 8
Bailey and Parmer Counties
August 2, 2002

Current Crop Conditions

Most cotton is nearing cutout. Fields that do not have the irrigation capacity to produce maximum yields with out rain have already cutout. When accumulated heat units from the day of cutout reaches 450, bolls are relatively safe from pests. Square and small boll shed is increasing every day, some due to insect damage but most because of the plants inability to feed all fruit that was initiated. Factors that contribute to a cotton plants ability to sustain fruit include available moisture, adequate nutrients (N, P, & K etc.), heat, and pest damage.

Corn earworms as well as stink bugs have been found in black-eyed peas and pinto beans. Plant diseases continue to cause problems as well. Some are treatable with fungicides and or copper.

Spider mite colonies are expanding in some corn fields while other fields are just simmering. Fall armyworms and southwestern corn borers continue to be a concern in corn.

Daily Water Requirements

Crop
Inches Per Day
Cotton
.27-.30
Corn
.31
Grain Sorghum
.27

 
Heat Units
Current
2001
Corn (April 1st planting)
2349
2304
Cotton (April 20th planting)
1275
1247
Cotton (May 1st planting)
1247
1210
Cotton (May 15th planting)
1182
1152

Bollworms

Regular whole plant counts of bollworms are necessary to monitor the status of this pest. With a lot of cotton cutting out hard there will not be much to feed on other than fruit that has achance to fully mature. With the exception of a few fields in southern Bailey County egg lay has just started trickling in. Treatment may be justified when counts average 5,000 or more small worms per acre. However, if two or more key predators are found for each small worm, control measures may not be needed or a microbial insecticide may be used.

Beet Armyworms

Beet armyworms are being found in higher numbers east and southeast of Lubbock. Occasional BAW are being found in crops in Bailey and Parmer Counties.

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Hopefully they will not develop in high numbers here, but close tabs should be kept on them. The BAWs in Lubbock are acting similar to the outbreak here in 2000, they are hatching feeding for a short time on foliage before dispersing to squares and bolls. With this kind of feeding activity whole plant counts need to be made across the field to determine the infestation level. The threshold for foliage feeding BAW is 20,000 worms per acre with at least 10% of the examined plants infested. If feeding has shifted to squares, blooms, and bolls the threshold should be reduced toward the bollworm threshold of 5,000 small worms per acre. Beet armyworm eggs are laid on both leaf surfaces in masses covered by a whitish, velvety material. Caterpillars are overall green or marked in shades of green with stripes, grows up to about 1 1/4 inches long, and can best be identified by a characteristic small black spot on each side of the second body (thoracic) segment behind the head.

Headworms

Scouting for the headworm complex (corn earworm and fall armyworm) in sorghum should continue till the head is no longer susceptible to damage. Natural mortality of small corn earworm larvae is normally very high. The economic injury level is about 1 to 2 larvae per grain head of commercial sorghum. Fewer larvae per grain head may justify treatment on sorghum grown for seed because of the higher per-acre value.

Boll Weevil Eradication

No boll weevils were caught north of Hwy 145, 8454 traps inspected. One boll weevil was caught south of Hwy 145, 11524 traps inspected, 98.7 acres sprayed. Failed cotton must be kept non-hostable to avoid the TBWEF assessment.

Trapping
Beet Armyworm
North of Hwy 145 808 in 25 traps
South of Hwy 145 211 in 25 traps
Corn Earworm 249 in 6 traps

Sorghum Midge

The adult sorghum midge is a small, fragile looking, orange-red fly with a yellow head, brown antennae and legs and gray, membanous wings. Sorghum midge damages sorghum when the larva feeds on a newly fertilized ovary, preventing normal kernel development. Sorghum planted and flowering late is especially vulnerable to sorghum midge. Often grain sorghum in Bailey and Parmer Counties is finished blooming prior to the arrival of midge but don't assume this, as losses can be great.

Monti Vandiver
Extension Agent-Integrated Pest Management
Texas Cooperative Extension
401 3 rd Street
Farwell, Texas
806-481-3300
Educational programs conducted by Texas Cooperative Extension serve people of all ages regardless of socioeconomic level, race, color, sex, religion, handicap or national origin. The information given herein is for educational purposes only. References to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Texas Cooperative Extension is implied.
The Texas A&M University System, U.S. Department of Agriculture, and the Commissioners Courts of Texas Cooperating
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