GENERAL SITUATION

Scattered showers fell again this past weekend depositing from 0.25 to over 2.5 inches of rain across the Southern Blacklands. Corn and sorghum are maturing rapidly. Cotton ranges from pinhead square to peak bloom.

CORN AND SORGHUM SOIL INSECT PESTS

A few late fields of sorghum have not completed bloom and are heavily infested with sorghum midge. Fortunately this only applies to a few fields and these fields will soon be past bloom stage.

COTTON INSECTS

Cotton ranges from pinhead square to having medium-size bolls. Fleahopper pressure continues to remain light in all fields, especially in fields of replanted cotton that are just beginning to square good.

Aphids pressure is variable across the area. For the most part, aphid pressure is very light. There are some fields where aphids are increasing and need to be closely monitored. At this time, no fields are requiring any treatments for aphids but that could change fast, especially after fields are sprayed for other pests which will cause a reduction in beneficial levels.

Cotton bollworm/tobacco budworm (CBW/TBW) pressure is on the increase across the area. Egg counts are ranging from 0 - 30 per 100 plants and larval counts are ranging from 0 - 18 per 100 plants. Most fields are averaging 4 - 8 eggs and 4 - 8 larvae per 100 plants checked.

This increase in worm pressure is expected to continue for at least another week. Currently, high levels of CBW moths are emerging out of local fields of corn. Fortunately, high levels of moths do not always translate into cotton fields being infested with high levels of eggs and worms. It is still to early to try to predict what will happen. But what is assured is that fields that have recently been treated with broader spectrum insecticides for other insects, for example, boll weevils, are more likely to run into worm problems than fields that have not been recently treated with an insecticide.

Thresholds for bollworm/budworm are 10 to 15 small larvae per 100 plants and 10 to 15 percent of the fruit is damaged. In cotton, recently sprayed with an insecticide and beneficials eliminated, the threshold can be lowered.

Bts, Spinosad and ovicides/larvacides labeled for bollworm/budworm control are products of choice this stage of the season. There have been a few pyrethroids that have already been used. Be sure to reserve these types of products until absolutely necessary.

Boll weevil damage is increasing rapidly across the Southern Blacklands. Punctured square counts range from 0 - 50 per 100 squares checked. Currently, most fields are averaging 6 - 12 punctured squares per 100 squares checked which has about doubled from last week.

Growers should be prepared to treat for weevils if they continue to increase at such a rapid rate. Many fields are triggering weevil applications and some are being put on a 4 to 5 day spray schedule.

Some insecticides for boll weevil control include: Guithion 2L at 1 pt./ac., Vydate C-LV at 1 gal./15 ac., Thiodan 3E at 1.33 pt./ac., Phaser 3E at 1.3 pt./ac., Thiodan 2CO at 1.5 to 4 pts./ac., MPT (methyl parathion 2 plus Thiodan 3EC) at 1.5 pts./ac., Penncap M 2F at 1 pt./ac. Generic Azinphosmethyl may also be used at 1 pt./ac.

Many of the synthetic pyrethroid insecticides that control bollworms also will provide some boll weevil control. However, application intervals similar to the traditional phosphate insecticides (3 to 5 days under heavy pressure) may be necessary to provide adequate control. When treatments are to be made for a bollworm-weevil complex, a suggested treatment regime is to use a pyrethroid followed 3 to 5 days later by a phosphate boll weevil insecticide. Since pyrethroids are not more effective than phosphates for boll weevil control, but are more effective for bollworm control, they should be saved for bollworm management. In addition, the use of synthetic pyrethroid insecticides may increase cotton aphid numbers.