HEAT UNIT ACCUMULATION UPDATE

As of July 31, 2002:

Heat units (HU's) are helpful in predicting plant maturity as an average. For example, it takes an average of 1410 HU's to reach peak bloom with an average time of 90 days from planting (85 to 95). We currently have accumulated the HU's but have not completed the time requisite with only 82 days completed for May 10th planted cotton which should have reached peak bloom if no delays (stresses) have been experienced. Since most fields are much later-planted or have been replanted, we can expect a predictably later crop this year.
Cotton is doing well under strong irrigation. If irrigation water is weak or has been slow in application, some thicker and more lush stands of cotton that looked excellent two weeks ago are starting to shed some small ½ inch bolls with blooms still attached. There is still some minor bollworm damage to small squares in most fields, but predominately this week we are finding small bolls (and squares) on the ground that didn't get water on time.

Dryland fields are "bloomed out" and have shed fruit as well in some cases.

Insect problems with bollworms in cotton are through for the time being. A small number of extremely large worms remains in all fields but they are certainly not worth treating.

Beet armyworm flare-ups have been reported in Lubbock County by Brant Baugh, Lubbock County IPM agent. These are primarily south and east of Lubbock and have been measured up to 47,000 worms per acre.

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. No problems currently exist in local program fields but we have another 40 days left in the vulnerable stage of this crop. More as this develops.

No new bollworm or beet armyworm eggs are being reported from program fields. No aphid problems have been reported in any program fields even though some can be found in almost any field in the plant terminals, in flowers and within square bracts.
Bollworm, aphid and beet armyworm treatment choices, as well as other pests, can be obtained from Texas Cooperative Extension's Cotton Guide. This guide is available on-line or at your local county Extension Office.

Bollworm, budworm and beet armyworm moth catches as of July 25th have captured:

Moth flight trends (bollworm/budworm) are generally down over the last few weeks with corresponding egg-lay at zero. BAW moth trap catches have risen overall by a small percentage except for Site 2 up from 42 on 7/24. This may be a precursor to what is being experienced currently in Lubbock County. To date, few larvae have been witnessed in program fields other than those feeding on careless weed (pigweed).

Pumpkin and ornamental gourd production is improving due to much-needed irrigation applications, continuing flowering and fruit-set and the presence of favorable, open-weather conditions. Scattered plants throughout the area are showing disease symptoms, but overall, cucurbits are doing very well. Portions of samples (as high as 80%) of disease-symptomatic plants submitted to the lab over the last three weeks have been found to contain the causal bacterial agent for Cucurbit Yellow Vine Disease (CYVD) which is devastating to watermelons, cantaloupes, pumpkins and other cucurbit crops. A proven vector and over-wintering reservoir for this disease has been the squash bug which is sometimes prominent in large numbers in local fields. Insect problems requiring recent pesticide intervention have been few but necessary where squash bugs have established in older, closed-canopy fields. Scouting fields on a three day schedule is the best way to keep a handle on these pests, especially with the large leaf surface-area of this crop.

Boll weevil trapping data (Texas Boll Weevil Eradication Foundation) has maintained 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.

Steve Davis
Extension Agent-IPM
Crosby/Floyd Counties

Posted at this web site by:
texagnet Internet Services.