GENERAL SITUATION

Heavy thunderstorms rolled through much of the area on Sunday evening resulting in as little as 0.1 to over 3 inches of rain. Most of the rain fell in a 30 minute period and was accompanied by very high winds and hail. The area hardest hit was the area on the Northeastern edge of Travis county. The storms came at a critical time for the corn, but also resulted in some damage due to the high winds and hail. The cool front that blew in on Tuesday morning is ideal for the corn crop, but the cotton does not respond well to the cool nighttime temperatures.

Much of the earliest planted corn is tasseling. The earliest planted grain sorghum is making good growth, and even the later planted sorghum is starting to make progress. Cotton ranges from still be planted to nearly one-third grown square with the majority around pinhead square.

CORN AND SORGHUM SOIL INSECT PESTS

Currently, populations of adult Mexican Corn Rootworm (MCRW) are being found in fields of continuous corn. Corn rootworms, of course, are among the most economically important pests of corn in the Southern Blacklands. Conventional soil insecticides provide only partial control of MCRW. Many fields where full label rates of soil insecticides were used are currently infested with this pest. Crop rotation is key to keeping this pest under control.

Everyone who has continuous corn for two (2) consecutive years or more needs to inspect their fields for mexican corn rootworm adults when the corn just begins to tassel. Much of the continuous corn shows the characteristic "goose-necking" caused by mexican corn rootworm feeding on the roots. The adult MCRW looks like the adult southern corn rootworm (spotted cucumber Beetle) except without the spots. The adult beetles lay eggs at the base of the corn plants (around the root) when the corn silks. The eggs will remain dormant until next Spring (April). They will then hatch and attempt to find roots of corn to feed on. By April, soil-applied insecticides and seed treatments are expected to be depleted and the larvae can feed on the roots, potentially causing reduced yield and can lead to lodging. Therefore, it you see the adults in the field now, you can expect to have viable eggs that hatch next spring into whatever crop is there. High levels can cause enough damage to the corn to cause a reduction in yield potential. This is a result of the root pruning caused by the population of MCRWs.

I had the opportunity to see some fields of one grower in Southern Williamson county that has third year corn and where a full rate of soil insecticide was used. There was one field in particular where the insecticides boxes on the outside row of the planter must of choked up and the corn in the two rows was completely on the ground. The rest of the field had evidence of insect injury which can be expected from areas where heavy populations of corn rootworm persist, but not near the extent were the insecticide was used.

COTTON

Thrips numbers are variable as is usual for this time of the year. Some fields have recently show considerable injury from thrips. Although much of the cotton is approaching the stage where thrips will no longer be a concern. Fields that have cotton that is smaller than pinhead square need to continued to be monitored for thrips until the cotton reaches the pinhead square stage.

Aphids levels are remain relatively low. As mentioned in the last newsletter, expect to see an increase in aphid populations following fleahopper and overwintered weevil insecticide applications.

Fleahopper levels remain high in area fields. Currently, fleahopper counts range from 4 to 45 per 100 plants. Most fields which are at pinhead square are averaging between 15 to 30 per 100 plants. Many of these fields were treated last week for fleahoppers and the numbers remained relatively light until about Tuesday, which is due to migration into cotton form nearby host plants.

During the first three weeks of squaring, 10 fleahoppers per 100 terminals may cause economic damage. Be sure and carefully monitor fields for adult and nymph fleahoppers.

Some recommended insecticides to manage fleahoppers include Bidrin at 1 gal/40ac, Dimethoate 4E at 1 gal, 1/16 Othene (90S) at 4 oz/ac, Provado at 3.75 oz/ac, and Vydate CLV at 8oz/ac.

Boll Weevil trap catches remain low this week. 1999 was a year when boll weevils levels were relatively light until late June. By this point in the season, we normally find an adult or two in fields of cotton, but we have not found any as of now.

The trap catches thus far this year would suggest that weevil levels could be lower this season than in . 99. Lets hope this trend continues across the entire season.

Some suggested insecticides labeled for overwintered boll weevil include Guthion 2L @ 1pt/ac, Phasar 3E at 1pt/ac, Vydate CLV at 8.5 oz/ac, and Penncap-M 2F @ 1pt/ac. For products such as Guthion that do not control fleahoppers, it may be necessary to tank mix Bidrin, dimethoate, or Provado to achieve fleahopper suppression.

We saw a few signs of bollworms/budworms, loopers and beet armyworms over the previous two weeks, but there numbers have dropped to very low numbers as well over the past 7 days.

Grasshoppers are increasing in size, are causing more damage and thereby becoming more of a problem. There are areas where I have observed numbers as high or higher than that of last year. It is important to try to protect smaller crops from major grasshopper injury.

The next section on grasshoppers is from Glen Moore's, EA-IPM, Pest Profile Newsletter, Vol XXVI No. 3.

Grasshopper Management

Producers are encouraged to inspect border rows of fields near pastures, tree lines and road side ditches for grasshoppers. Heavy numbers of newly hatched nymphs are readily being observed in these areas. Hot and dry conditions are most favorable for survival of young hoppers. As these small hoppers increase in size and number, expect to experience potentially heavy feeding to row crop borders and desirable plants. The economic threshold for treating grasshoppers in field margins is 20 or more grasshoppers for square yard. Within a field, treatment should be made when 10 or more grasshoppers are present per 3 row ft. Some insecticides labeled for crops, pastures and homestead sites are listed.

Cotton

Orthene 75S at 1/3 to 2/3 lbs./ac., Orthene 97S at 4 to 8 ozs./ac., Sevin 80S at 0.5 to 1.5 lbs./ac., Sevin XLR Plus at 1 to 3 pts./ac. and dimethoate 4E at 1 pt./ac.

Corn

Warrior T at 2.56 to 3.84 ozs./ac., Asana XL at 1 gal./20acs., Sevin XLR Plus 1 to 3 pts./ac., Sevin 80S at 2/3 to 1 7/8 lbs./ac. and dimethoate 4E at 1 pt./ac.

Sorghum

Baythroid 2 at 1 gal./64 acs., Warrior T 2.56 to 3.84 ozs./ac. Sevin XLR Plus at 1 to 3 pts. /ac., Sevin 80S at 2/3 to 1 7/8 lbs./ac. and dimethoate 4E at 1 pt./ac.

Pasture

Malathion 57 EC at 1 ½ to 2 pts./ac. (no grazing restrictions), Sevin 4F and Sevin XLR at ½ to 1 qt./ac., Sevin WPS 2/3 to 1 1/4 lbs./ac. (14 day interval between application and grazing), Orthene 75 WSP at 2 to 2 2/3 oz./ac. (Beef cattle may graze treated pasture on the same day of application, but must be removed from treated area at least one day before slaughtering).

Lawns & Homestead Sites

Bayer Advanced, Tempo, Orthene, Sevin 80 WSP, Sevin XLR Plus, malathion and Neem. Also for those who prefer not to apply pesticides, now is an excellent time (while nymphs are small) to apply a biological control product, Nolo Bait or Grasshopper attack. These products contain spores of the disease agent, Nosema locustae