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Vol. XXIV, No. 9

Cotton has been standing up well against the hot dry conditions this past week. Scattered showers have not provided any widespread significant rainfall. Early planted cotton now has many blooms and quarter size bolls. Fields are still in the early bloom stage. A few late planted and replanted cotton fields are very close to bloom now.

Trap collections of beet armyworms have generally been low in the Cotton Center area, while one farm in the Kress area was up to 155 beet armyworms per day on July 13. Larvae of the beet armyworm have been found in many fields but populations have remained light.

Cotton fleahoppers and Lygus have been in most cotton fields this past week. Damage remains variable with square sets ranging from 72% to 98%. We have generally been very conservative on treating for plant bugs this year, because of the potential of creating secondary pest outbreaks and the beneficial populations have excellent in many fields sampled over the area. Crab spiders and damsel bugs remain prominent beneficials, but we are seeing a significant increase in pirate bugs and big eyed bugs.

Be very cautious about treating for this pest. We have never developed an economic threshold for the whitefly species that occurs on cotton in the Texas High Plains.

Cotton bollworm damage remains low as light populations have bee reported in an occasional field.

NOTE: We have established economic thresholds for many cotton pest in our cotton guide, but in general they were developed for cotton valued at 65 cents per lb. If we expect our final value to fall below this target we may occasionally opt to move toward the high end of a threshold range or adjust a static threshold up from what we have used in the past. While this may not be true for every pest, it will be for many.

Southwestern corn borer trap collections remain high and egg lays are proceeding. When scouting for southwestern corn borer eggs one should examine 2 leaves above the ear leaf to 4 leaves below the ear leaf for a total 7 leaves per plant. Look at both the top and bottom side of the leaf surfaces for eggs. Eggs are small and laid flat on the leaf surface and are overlapping each other like shingles on a roof or fish scales, when laid in clusters or masses. When eggs are first laid they are creamy white in color then at around 24 hours they develop 3 red stripes across the egg. This makes them much easier to detect on the leaf surface. After five days they hatch and move behind leaf collars to feed on secondary and primary ears. After seven to eleven days they begin to bore into the corn stalk.

With the hot dry weather Banks grass mites have been much easier to find in area corn fields. The following table developed by Dr. Tom Archer will help you determine a treatment threshold.