IN THIS ISSUE

· TPMA Website
· Cotton Insect Situation
· Bollworms versus Budworms
· Mexican Corn Rootworm Scouting Program
· Did You Know

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 one-third grown square through the second week of bloom throughout the Tri-County area of Wharton, Jackson and Matagorda counties.

Aphid numbers remained light during the past week. Ninety-four percent of the fields monitored were considered to have light infestations.

Boll weevil punctured square counts were low during the past week. Boll punctured square counts ranged from 0 to 3%, 0 to 2%, and 0 to 4% for the fields that were monitored in Jackson, Matagorda and Wharton Counties, respectively.

Bollworm numbers and damage square counts remained light for the Upper Coast area.

Bollworm egg, larvae and damaged square counts ranged from 0 to 6%, 0 to 1%, and 0 to 2%, respectively for the fields that were monitored in Jackson county.

In Matagorda county, field counts for egg, larvae and damaged square counts ranged from 0 to 2%, 0 to 3% and 0 to 3%, respectively.

In Wharton county, field counts for egg, larvae and damaged square counts ranged from 0 to 4%, 0 to 2% and 0 to 4%, respectively.

For determining if an insecticide treatment is required, fields should be carefully scouted at least once a week and twice weekly during peak periods of egg deposition. Eggs and newly hatched worms are usually found in the plant terminals and indicate possible outbreaks. Frequently, examination of the upper third (terminal) of the plant (leaves, stems, squares, blooms and bolls) for eggs and small larvae is all that is needed to make sound management decisions. However, moths sometimes deposit eggs on the fruit and stems lower on the plant. This may occur when cotton plants are stressed and making little new growth.

Carefully scout fields for eggs, newly hatched worms and damage. Examine 25 plant terminals selected at random from at least four sites in fields for eggs and small larvae. Also examine the same number of one-half and larger green squares for bollworms and damage. These squares should be selected at random and flared or yellow squares should not be included in the count. Once blooms are present, an insecticide application may be justified when 8-12 or more small larvae are present per 100 plant terminals and 5-15% of the squares and bolls are worm damaged. If worm numbers are high, it may not be appropriate to wait until the damaged square threshold is reached. If insecticides have already been applied that kill beneficial arthropods, treatment may be justified when infestations reach or exceed 4-5 small worms plus eggs per 100 terminals and 5% of the squares and small bolls have been damaged by worms.

Saltmarsh caterpillars (SMC) continue to be found in fields. Sixty-three percent of the fields that were monitored during the past week contained salt marsh caterpillars. All of the fields with the exception of one contained SMC in low numbers.

Loopers were found in very low numbers in 14% of the fields that were monitored during the past week. Also, tarnished plant bugs or lygus and brown stink bugs were found in low numbers in 5% and 3% of fields, respectively.

Beneficial insects that could be found readily during the past week included lady beetles, minute pirate bugs, lacewings, and syrphid flies. Spiders were found as well.

Bollworms versus Budworms

Moth trap catches for first week of June show that about 87% of moths that were caught are bollworm. (See Chart 1)

Also included is a five-year comparison of the percent number of bollworm and budworm moths caught for the first week of June. (See Chart 2)

Mexican Corn Rootworm Scouting Program

Numbers of Adult Mexican corn rootworm beetles have begun to decline in the fields that are being scouted. Corn silks in most of the fields have begun to dry. As this years scouting program is winding down, about 35% of fields required one insecticide application based on the economic thresholds that were set. Appreciation is expressed to the Texas Corn Producers Board for funding this program.

Did You Know

Wireworms

The term wireworm describes the larvae of adult click beetles (Family Elateridae). Because the various genera of plant-feeding elaterids are widespread, wireworms are also cosmopolitan and are found in almost any kind of soil.

Wireworms are polyphagous and feed readily on numerous hosts while in larval form. They injure crops by devouring seeds in the soil, cutting off small underground stems and roots, and boring into larger stems, roots, and tubers.

Adult click beetles are hard-shelled, 7 to 25 mm long (depending on species), brown to black to gray, with a tapered body at each end. The name click beetle refers to the clicking sound emitted by adults as they flip their body to right themselves. Larvae (wireworms) are slender, cylindrical, 7 to 35 mm long, hardened, and yellow to brown. Adults and larvae vary in details of appearance, depending on species.

Wireworms have varied life histories depending on species, but some aspects of development are similar. Adult females lay eggs singly in the soil, 2 to 15 cm deep during the spring. Hatching occurs in 14 to 30 days, and young larvae move within the soil to locate a food source. Larvae feed in the soil for 1 to 6 years, with much overlap of generations.