HEAT UNIT ACCUMULATION UPDATE

As of August 8, 2002:

Cotton continues to develop on track if not stressed. Most irrigated cotton is at 0 to 2 nodes above white flower (NAWF) stage and is cutting out, weaker irrigated is past physiological cut out and semi-irrigated or dryland is dropping leaves and "quarter-size" fruit. Bolls are still very soft and vulnerable in most heavily irrigated fields and will require close monitoring throughout the month of August. 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 but are not excessive as 2001 experienced in June and July.

Insect problems with bollworms in cotton are decreasing in Crosby and Floyd Counties with no treatable levels of worms, as of this writing, in program cotton. The usual 2 to 3,000 eggs and 3 to 4,000 worms can be found in most program cotton but survival is questionable with current weather and increasing beneficial numbers experienced this week.

Beet armyworm flare-ups have been reported in program cotton and pumpkins but none have had to be treated to date. Populations of this pest will need to be monitored closely as host weed species are maturing becoming less attractive and irrigated crops become more attractive with our current dry weather patterns.

Aphid problems that were imminent in program fields last week are all but gone as "mummies" from parasitic wasps have appeared in large percentage this week as well as ladybeetle larvae and adults, green lacewing larvae and Syrphid fly larvae.

Aphid problems that have had to be treated with the insecticide Intruder ® at 0.6 ozs. have really been "smoked" at three days post-treatment.

Sorghum head worms ( bollworms and fall armyworms) are increasing in late seed sorghum fields with populations ranging from 1.2 to 2 worms per head, which is above threshold. Instars range from 2 to 12 day-old worms with beneficials seemingly happy to feed on corn leaf aphids in the head rather than the worms.

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 evident. BAW moth trap catches have risen overall with site 2 exhibiting the largest change in the last month's 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. Aphid populations were on the rise in pumpkins until this last week when parasites creating "mummies" began to appear as in cotton.

Powdery Mildew has been noted in areas of cucurbit fields where irrigation water has been allowed to pool but the incidence of this disease is not widespread at this time.

By now, everyone has heard of the outbreak of West Nile Virus in Floyd, Briscoe, Swisher, Oldham and Parmer Counties of Texas. It is spread via the bite of an infected mosquito. Mosquito breeding sites may be eliminated by removing standing water, mowing or tilling tall weeds and mosquito-proofing animal dwellings. People can protect themselves by avoiding outdoor settings with heavy mosquito numbers and wearing personal insect repellant containing DEET if outside for extended periods.

Any additional information regarding WNV may be researched on the TDH website at tdh.state.tx.us or by calling your local Texas Department of Health office.

Dr. James Glasson, D.V.M. in Lockney is an excellent local source of information on this subject.

Boll weevil trapping data (Texas Boll Weevil Eradication Foundation) has remained on track in both the Southern Plains/Caprock and in the Northern Plains Zones with 0.002 and 0.004 weevils/trap, respectively. The Southern High Plains/Caprock and the Northern High Plains Zones have treated approximately 271,000 and 110,000 acres of cotton, respectively, for boll weevils as of August 4, 2002.

Steve Davis
Extension Agent-IPM
Crosby/Floyd Counties

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