CURRENT CROP CONDITIONS
The area cotton crop is continuing on schedule with fields well past cutout and open bolls are a common site in program fields. The hot temperatures combined with little or no rain is sending this cotton speeding into cracked boll. Several program fields are wrapping up irrigation chores at this time but most fields will continue to be irrigated for the next 14 days. Insect pressure remains heavy this week, but most fields are now safe from worm feeding or have less than 20,000 worms per acre. The late planted June cotton is really taking a beating from worm pests this week. Control decisions are tough for this cotton due to the fact that I cannot guarantee that these fields will have enough time to obtain the magical 850 heat units past cutout which determines when the field can be defoliated. The late planted cotton must have an open Fall in order for the worm applications to pay off. The COTMAN computer model is still saying that fields can be defoliated starting on September 4 through September 24 for most of our program fields. However, COTMAN is saying that the projected date of 850 heat units after cutout cannot be determined for June planted cotton that has not cutout at this time. Keep in mind, these projections can change weekly due to temperature fluctuations.

WHAT THE SCOUTS ARE FINDING
Since last weeks writing of this newsletter, the pest pressure has let up in some aspects and has increased in others. Cotton aphids have crashed in all program fields. This crash has happened overnight without any real explanation. We had a test field that was averaging over 200 per leaf and in two days the field was clean. This crash in population has happened in all program fields even those that were treated with a pyrethroid late last week.

Bollworm eggs are still being found in most program fields but are down compared to last weeks numbers. Egg counts are ranging from zero to 8,000 per acre. Total larvae are ranging from 0 to 15,000 per acre. In fields that were completely cutout last week and were not treated, worm counts declined from over 20,000 to less than 5000 this week with little damage done to bolls larger than a quarter and no large larvae present. This indicates to me that cotton is mature enough to withstand a fairly large worm population.

Beet armyworms (BAW) are still being found in every program field and the numbers seem to be increasing. However, in fields that have reached total cutout, we are seeing leaf feeding with very little boll damage and are finding very few mature larvae. The only fields that still have a problem with BAW is the June planted cotton. We have one case, where the producer decided not to treat his late planted cotton and we ended up with an average of three very mature large bolls per plant.

Fall armyworms (FAW) are being found in every program field. Worm counts are ranging from 5,000 to over 20,000 per acre. I did learn something about the control of this pest last week. Just through observation, the 6oz. rate of Intrepid gave me better control than the high rates of Fury, Decis and Karate. The intrepid fields are virtually clean and the pyrethroid treated fields are averaging 4,000 larvae per acre over ½ inch in length and 8,000 larvae per acre smaller than ½ inch. This tells me that the pyrethroids gave me a decent initial kill but lack in residual compared to the Intrepid treated fields. Keep in mind that this is only observation and not a replicated trial.

I guess the take home message would be that if you have late planted cotton and you are below threshold on bollworms but have a treatable population of FAW, then I would use Intrepid. You will keep most of your beneficial insect population intact, will not flare aphids, and will control beet armyworms. If you are over threshold on bollworms, and FAW then I would use Karate and at a high rate. If you have economic infestations of bollworms, FAW, and BAW then you need to mix the pyrethroid with the Intrepid.

Suggested insecticides for beet armyworm control

Suggested Insecticides for control of bollworms.

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