GENERAL SITUATION

Scattered thunderstorms have delivered between 3 to 8 inches of rain over the last 2 weeks across the Southern Blacklands. Along with the rain came some barely noticeable hail damage which was evident in fields following the storms. Some of the earliest planted corn and grain sorghum is really putting out a lot of new foliage. Cotton is up to a stand and is making good progress.

CORN AND SORGHUM SOIL INSECT PESTS

It is time for populations of adult Mexican Corn Rootworm (MCRW) to begin emerging from fields of continuous corn soon. MCRWs are among the most economically important pests of corn in the Southern Blacklands. They are generally only a problem in fields that have been in corn for three or more consecutive years. Many conventional soil insecticides provide partial control of MCRW.

Chinch bugs continue to be found hurting corn in a few isolated fields throughout the area. Corn leaf aphids have almost been non-existent in corn and grain sorghum this season.

In grain sorghum, corn leaf aphids, greenbugs, and yellow sugarcane aphids have been light thus far this season. There are some areas where the sorghum crop looks like it is in great shape considering when it was planted and others that are just the opposite.

COTTON

Cotton ranges from just being planted to pinhead square with most fields at the 3rd -4th true leaf stage. For the most part, fields of cotton are in good shape with good stands and moisture.

Producers with Roundup Ready® cotton need to keep up with the plant stage very carefully right now and be sure that if you want to apply a Roundup® product over the top that it needs to be sprayed before the cotton reaches the fifth true leaf stage. The majority the cotton will be at fifth true leaf stage before May 21. After the fifth true leaf stage, Roundup Ready® cotton can be sprayed with a hooded sprayer or post-directed to clean up any remaining weeds in the cotton.

Currently, thrips levels are very variable, with averages ranging from 1 to over 2 thrips per plant. Heavy infestations of thrips may destroy a high percentage of terminal buds, causing excessive branching. Therefore, really look at the cotton and your insect counts to determine what level of thrips are present, how much damage is being sustained, the stage of the crop before making any management decision. Many times early symptoms of damage will be deformed true leaves, which can be used in conjunction with insect counts to base management decision from. Heavy thrips numbers can stunt plants, delay fruiting and reduce stands. Thrips can cause damage from the cotyledon stage up to about the 6th true leaf stage.

Some insecticides for thrips include Bidrin at 1 gal/60 ac, dimethoate 4E at 5 to 8 oz./ac, Moniter 4E at 3.2 oz/ac, and Methylparathion 7.5 E @ 1 gal/ac. Producers should closely monitor pre-squaring cotton for thrips. Treatment should be made when slight terminal leaf curling is observed and thrips are readily found on plants.

Aphid levels are relatively light in fields. Levels run from none to 8-10 infested plant per 100 plants checked.

Fleahopper levels are jumping up quickly in area fields. Fleahopper counts in the oldest fields have jumped up to 28 fleahoppers per 100 plants checked. There are just as many nymphs that cotton already as there are adults. From everything that we have seen, this will be a heavy fleahopper season. Some fields have already been sprayed for fleahoppers and others will be sprayed by the beginning of next week. Fleahopper levels will undoubtedly increase over the next few weeks in fields of cotton.

It is not uncommon to see noticeable levels of adult fleahoppers in fields of cotton prior to squaring. There is one field of cotton that is between cotyledon and 4 true leaves and is loaded with fleahopper nymphs already. It appears that the fleahoppers moved off of weeds in the field following an early shot of Roundup® and onto the cotton where they are feeding in the terminal, similar to how thrips would feed. It is really unclear if the damage being seen is from in part the result of the fleahoppers or just thrips. But it is very odd to see so many nymphs in cotton of this stage.

When deciding on whether or not to make a fleahopper insecticide application, consider number of fleahoppers present, and percent square retention or percent blasted squares. Do not just spray because your cotton is beginning to square, scout it first. If numbers of fleahoppers are high and the cotton is just beginning to square, you will not have any square counts to make and have to then make your management decision based strictly on number of fleahoppers present.

During most years, I would say that if the cotton is just starting to square with less than one fruiting node per plant, more damage may be tolerated to allow a large percentage of plants in fields to begin squaring. However, giving the lateness of our crop, we cannot afford to allow early season fruit loss. We have to try to aggressively set a good fruit load early

During the first three weeks of squaring, 10 -15 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 1gal/40 ac, Dimethoate 4E at 1 gal, 1/16 Othene (90S) at 4 oz/ac, Provado at 3.75 oz/ac, and Vydate CLV at 8 oz/ac.

Boll weevil traps were run for the first time this week. You can see on the table above that the number of weevils caught during roughly the second week of May in 2001 was considerably lower than last year and lower than in 1999 which was a relatively light boll weevil year, especially early, as well.