HEAT UNIT ACCUMULATION UPDATE

As of August 8, 2002:

Cotton continues to flourish with strong irrigation capabilities. Most irrigated cotton is at the 5 to 7 nodes above white flower (NAWF) stage, weaker irrigated is 2 to 4 NAWF and semi-irrigated or dryland is "bloomed out". Bolls are still very soft and vulnerable in most fields and will require close monitoring throughout the month of August. Drier fields are shedding squares and dime to nickel-size bolls, insect-damaged and seemingly healthy, to maintain the plant. Boll maturation, depending upon available moisture, needs 18 to 45 days to establish fiber length and an additional 20 to 60 days to determine micronaire and fiber strength. Heat units are plentiful this year and are not excessive as 2001 experienced.

Insect problems with bollworms in cotton are causing concern in neighboring counties of Lubbock and Hale. Egg lay has begun in spots in Crosby County with no treatable levels of worms, as of this writing, in program cotton ; there certainly may be some out there that needs chemical intervention at this time. This problem will need to be pondered over the next week to ten days as the possibility of another bollworm fight is potentially imminent.
Beet armyworm flare-ups have been reported in Lubbock and Hale Counties, as well. This particular pest infestation is exhibiting bollworm-like

characteristics of feeding on squares and bolls rather than acting as a leaf-feeder which is their usual nature in pigweed host plants. No problems currently exist with "beets" in Crosby/Floyd program cotton fields even though program moth traps have shown an increase in activity over the last two week period that usually precedes such an egg lay and worm infestation.

Aphid problems are imminent in program fields as populations are being found in almost any field in the plant terminals (top and bottom sides of leaves), in flowers, on main stems, leaf petioles and within square bracts with honeydew very evident to the most casual observer. The threshold of fifty per leaf is easy to find in spots with entire fields usually averaging much less. As these spots grow and intensify in density, chemical intervention will be necessary. I think we would all like to wait on bollworm populations to treat for aphids, but don't think this approach can be practiced in most cases this year.

Bollworm, aphid and beet armyworm treatment choices, as well as other pests, can be obtained from Texas Cooperative Extension's Cotton Guide. Several treatment choices are available this year for single or multi-pest applications with ground, aerial and chemigation applicability. This chemical guide or "menu" is available on-line or at your local county Extension Office.

Bollworm, budworm and beet armyworm moth catches as of August 8th are:

Moth flight trends (bollworm/budworm) are up slightly over the last few weeks with corresponding egg-lay just becoming evident. BAW moth trap catches have risen overall with Site 2 exhibiting the largest change in the last two week trapping period.

Pumpkin and ornamental gourd production is doing very well. Insect problems requiring recent pesticide intervention have been few but necessary where squash bugs have established in older, closed-canopy program fields. Fresh eggs and newly-hatched nymphs are the easiest sign of an infestation as the adults are extremely cautious and elusive especially in the heat of the day. Early morning is the opportune time to find adults, especially with the large leaf surface-area of these crops. There is no immediate threshold of this insect in cucurbits, but one must develop a "feel" for the infestation and treat accordingly. Infestations of adults may kill individual plants within 3 to 5 days due to the Cucurbit Yellow Vine Disease bacterium that they transmit. Scouting on at least a three-day schedule for all life stages of squash bugs and their affinity with yellowed, wilted plants is currently the best method for approaching this problem. Through continued research we hope to develop a better handle on this pest.

Boll weevil trapping data (Texas Boll Weevil Eradication Foundation) has remained at a low level in both the Southern Plains/Caprock and in the Northern Plains Zones with 0.001 weevils/trap. The Southern High Plains/Caprock and the Northern High Plains Zones have treated approximately 362,000 acres of cotton for boll weevils as of July 28, 2002. Patrick Burson, Southern High Plains/Caprock Zone Manager for Texas Boll Weevil Eradication Foundation, indicates that treated acres currently are 1 to 1½ % of total acres in his zone, whereas previously, the routine involved 3 to 4 % of total acres.

Steve Davis
Extension Agent-IPM
Crosby/Floyd Counties

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