Cotton has made a lot of progress this week. Grain sorghum looks great in most areas with very little insect pest pressure. There are lots of natural enemies in sorghum now and these beneficials will be moving into cotton as the sorghum dries down. Fortunately, the sorghum has not needed an insecticide treatment so we conserved all those natural enemies.

Cotton aphids, cotton fleahoppers and bollworms are still present and causing some problems in several areas. With these insect pests and the cloudy cooler temperatures, it has been very difficult and challenging trying to load up this year's cotton crop. These are lots of cotton fields with square sets ranging from 65-80% and the growth stage is matchhead to 1/3 grown square stage. I would like to see the square sets in 85-95% range. Keep in mind our cotton crop is behind schedule, our plant stands are very erratic and growing conditions are good, making it difficult to manage, therefore, it's very important to set our crop as quickly as possible. We cannot rely on a fall like we had last year. Also, keep in mind insect pressure is usually much higher late in the season.

Cotton ranges in growth from 6th true leaf to bloom/boll stage. The vast majority is approaching 1/3 grown square stage or just past this stage. Square sets average 75-80%. Cotton fleahopper numbers range from 0-77 fleahoppers per 100 plants. Bollworm egg counts have dropped off from last week and range from 3-28 eggs per 100 plants. Bollworm larvae range from 0-28 treatable worms per 100 plants. Non-Bollgard® cotton planted on irrigated ground needs to be scouted closely for worms now as well as for fleahoppers, aphids and square retention. It's time to load it up. Bollgard® varieties are taking a small hit from this pest egg-lay as well. You can find a few small worms and see damage where they have fed on small squares. To date, worm damage has been minimal in the Bollgard® cotton. Non-Bollgard® varieties are certainly taking a hit from this past egg-lay. Scout your fields closely for small bollworm larvae feeding on plant terminals and small squares. Unfortunately, most of the infested cotton is pre-bloom pre-bloom complicating control decisions. I have a hard time recommending an insecticide treatment for bollworms prior to bloom.

In dryland situations, you must also consider your moisture situation. If your underground moisture is good, load it up now. If it is marginal, try to set and maintain an average of 4 to 5 squares per plant. I know this is a difficult time and turning your head and doing nothing may or may not be the right decision. It all depends on continued rainfall. If current conditions continue, it was the right decision; if hot-dry weather returns, not spraying was the right choice. Spraying now will protect the fruit set and the potential you have with current moisture and should give us sufficient time to see what the weather is going to do later.

I would not recommend the use of pyrethroid insecticides prior to bloom. Cotton aphid infestations are present in many fields and many fields have already required aphid treatments and the list of reasons could go on. Tracer, Steward and Larvin are all excellent larvicides and cause much fewer side effects. If a pyrethroid is used now, chances are very good that an aphid application will be needed within a couple of weeks. We are currently experiencing cool cloudy weather which is ideal for an aphid buildup. My philosophy is to clean it up now and allow natural enemies to build back up before the next egg-lay. Having to treat for aphids in two or three weeks could open yourself up for more worm pressure.

There have been a lot of questions about the use of Pix® and if it is needed. If you're in a dryland situation, use fruit (squares and bolls) as your Pix®. Applying 2-4 oz. of Pix® on dryland cotton with little to no additional fertility applied to the crop will do very little to help you set a crop. The best Pix® we can have is a boll. I have seen many times in the past, dryland cotton growing like it is now and in a week it's burning up.

Now on irrigated cotton, it's a different story. We have fertility under this crop, we can apply irrigation when needed and we are pushing the crop harder. Pix® is needed on much of the irrigated cotton and should be applied around first bloom.

The period of first bloom to open boll places the greatest demands on the plant. Any shortage of carbohydrates, water or nutrients at this time will reduce yield.

Through photosynthesis, plants produce the carbohydrates (sugars) that provide the energy for plant growth and development. Cotton leaves that produce more carbohydrates than they need are called "sources." These source leaves supply the carbohydrates for other plant parts, termed "sinks." Sinks include developing fruit, leaves, stems and roots.

During the first sixteen days after a leaf unfurls, the carbohydrates produced by that leaf are used for its own growth. Between days 16 to 25, the leaf reaches its prime as a source and exports its carbohydrates to other developing plant parts, such as bolls. At four weeks old, a leaf's carbohydrate production begins to slow until about day sixty, when the leaf can no longer export sugars. During the bloom period, the most active main stem leaf is five nodes below the terminal. At this time, the leaf 13 nodes below the terminal is nonfunctional.

Young squares can support themselves with carbohydrates from the bracts (triangular leaves immediately surrounding the flower bud). However, once the boll reaches ten days old, it demands a tremendous amount of nutrients and carbohydrates. It becomes a very strong sink.

A young boll derives most of its food from the leaf immediately below it, which is termed the subtending leaf (Table 1). If the subtending leaf of a 4- to 7-day-old boll is shaded - for example, because of cloudy weather or a thick stand - the boll may shed from lack of carbohydrate supply.

Of the final weight of the boll, the subtending leaf contributes 50 percent and the nearest main sten leaf 35 percent. The remaining 15 percent comes from leaves elsewhere on the plant.

Table 1. Carbohydrate sources to a first-position fruit.

Source: D. Oosterhuis et al. 1990. Leaf Physiology and Management. Cotton Physiology Today. National Cotton Council Physiology Education Program Newsletter 1 (8):1-6.l

Important Terms and Concepts in IPM

Economic Injury Level (EIL)- the lowest level of a pest that will cause economic damage, ie. The level of pests where the dollar loss caused by the pest exceed the cost of control.

Economic Threshold (ET)- the level of pest infestation when control should be applied to keep an increasing pest population from causing economical losses. The ET is also called the action threshold because it is the pest level where action should be taken so that economic losses are avoided.

The economic threshold is a key IPM decision-making tool. Thresholds are based on considerable amounts of research and/or field experience. If the economic threshold is approached, but not reached, do not apply a pesticide at that time. Instead, re-scout the field within a few days to determine the status of the infestation. Pest populations can decline naturally due to mortality from natural enemies and unfavorable weather conditions. Also, many pests, such as caterpillars, change from an active feeding (larva) to a non-feeding stage (pupa) during their development. Such changes will often produce a natural decline in infestations as pupation occurs.

The "IPM Updates" have begun. The telephone number to call is 365-2642. This update will give producers a general insect and crop report for the different areas in Runnels, Tom Green and Concho Counties that is being monitored by the cotton scouts. I would encourage you to use this service. This allows you access to the information at your convenience. If it is not used this year, we will discontinue it next year.

"Field Bindweed"

Field bindweed, sometimes called possession vine, is a viny, deep rooted, persistent, perennial weed that is a member of the morning-glory family. Field bindweed is easily recognized by its arrow-shaped leaves and its profuse 3/4 to 1-inch white to pink trumpet-shaped flowers.

How It Is Spread
Bindweed is spread both by seed and roots. Bindweed is usually spread to fields in contaminated
seed grain from dirty combines. Samples of seed grain have contained up to 26,000 bindweed seed per bushel. Seed are also scattered in manure by animals grazing on bindweed-infested land.

Once introduced to a field, new plants are produced from buds on lateral roots and, within on season, a single plant may spread up to 10 feet in diameter.

Cultivation can give rise to new plants from roots or rhizomes, if rain falls shortly after plowing. The seed are extremely hard, impervious to water, and can remain dormant and viable in the soil for more than 30 years.

Economics
Field bindweed covers about 600,000 acres of farm land in Texas and decreases crop yield 50 percent. Total loss from the 600,000 acres is over 50 million dollars annually.

County Tom Green BUDWORM/BOLLWORM MOTH TRAPS

Traps were baited May 16, 2002 - rebait every two weeks

County Runnels BUDWORM/BOLLWORM MOTH TRAPS

Traps were baited May 16, 2002 - rebait every two weeks

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