IN THIS ISSUE:

Cotton continues to grow rapidly where moisture is not in short supply but is slowing down considerably in dryland fields needing rain or in irrigated fields with parked pivots. Many of these fields are in danger of premature cutout. In these instances, we are no longer concerned about insect management. If growers are not going to irrigate where needed or are delaying irrigation until bloom, then early season insect control is a waste of time.

Increasing problems with cotton fleahoppers have been reported. More fields are experiencing reduced square sets and higher fleahopper numbers. The strange trend observed though is the low numbers of adults found while nymph numbers may be high. This is unfortunate since the smaller nymphs are harder to find. Most scouts will miss 1st instar fleahoppers unless they really look closely and slowly at each plant.

To really stay on top of the fleahopper situation producers should do some plant mapping during the first 4 weeks of squaring. Look for only first position squares since these represent at least 85% of your potential yield, even a higher percentage during the early fruiting period. If first position squares are retained but second position square set drops in the 3^rd and 4^th week, you are probably observing the approach of cutout in response to a heavy fruit load or stress due to some limiting factor.

The smallest 1^st position square you should be looking for is at the base of the rolled up leaf in the terminal that is just above the leaf that is beginning to unfurl. Count this position and work down the plant until about the 5^th or 6^th node above the cotyledons. Don't mistake a lower, non-fruiting position for a shed square location or you will overestimate square loss. Once square sets begin to fall and/or fleahopper numbers begin to approach treatment levels, you should be shortening your monitoring interval so that the bottom doesn't drop out on square sets between scouting trips.

There has been some concern about treating fleahoppers and causing a bollworm or beet armyworm outbreak later in the season because of the elimination of natural enemies. And we are detecting some increase in bollworm egg laying activity at this time. What you must first ask yourself is whether you are growing cotton or "beneficials"? If the answer is cotton then you still have options to preserve some of your natural enemies. Some products like Orthene, Lorsban, Provado, Steward and Vydate can be used at lower rates and preserve larger numbers of "beneficials" while protecting square set. An example of this is provided in Table 1. This was a rate test conducted by Deanna Holladay (former Extension IPM agent) using Orthene to control fleahoppers and yet maintain sufficient natural enemies to curb the July flurry of bollworms. The results of this test indicate that she was successful.

 Table 1. Cotton fleahopper control test. Scurry Co. 1985

Western tarnished plant bug (WTPB) problems are spotty across the area with highest numbers observed near prime alternate host locations. I know of very few treated alone for this pest. In most instances there was a combination of pests such as fleahoppers and WTPB or beet armyworms to address. This could change over the next several weeks. Producers are cautioned to select those insecticides and rates that can adequately address this tougher-to-kill pest. Best bets include Orthene, Bidrin and several of the pyrethroids (with the proviso that you might flare aphid infestations). Also, producers and consultants are cautioned to look at our current management guide. We no longer count nymphs as two in sampling cotton as we did in the past.

Texas Boll Weevil Eradication Foundation BAW traps have caught fewer moths this week in all High Plains Zones, but the Northwest Plains Zone (NWP) is still catching 4.6x more moths than Western High Plains Zone traps and 13.5x more moths than Permian Basin Zone traps. This is the complete opposite of what happened last year when southern trap numbers were increasing and northern trap catches were declining. I believe this reversal is the result of one primary factor. A huge overwintering population of BAW must have been present in the NWP following high caterpillar infestation levels late last season. This was not the case with the southern area where beet armyworm numbers crashed as cotton cutout early in the season.

 Table 2. Comparison of total boll weevil GRID trap catches for the 6 week period, May - June 22, 2000-2001.

Aphids numbers are slowly beginning to build. For the most part these infestations are concentrated in the terminal area. Once aphids spread to lower leaves you can anticipate a rapid buildup. Basically the risk of aphid problems will come from one of the following situations: late planted cotton carrying higher levels of nitrogen into August, excessive nitrogen fertilization, and pyrethroid use. You might even include the use of Larvin or Steward in situations where ladybeetles are abundant. Don't be in a hurry to treat these early infestations. But if you must treat, Furadan 4F, Bidrin (high rate), and Centric appear to be the best bets.

Natural enemy numbers remain relatively high and consist mainly of crab spiders, big-eyed bugs, damsel bugs and minute pirate bugs. There are some ladybeetles present in those fields with a few aphids lurking in terminals, but they are few and far between. The big news is the abundance of crab spiders this year. I believe they are almost single handedly keeping most fleahopper and beet armyworm infestations down at sub treatment levels. Our best caterpillar predators will be the minute pirate bug, damsel bug and big-eyed bug. Our best aphid predators will be syrphid flies, ladybeetles, and lacewings. Spiders will probably be our best fleahopper predators. Remember that our predators are generally opportunistic feeders, not distinguishing between the good guys and the pests. It is not uncommon to observe one predator feeding on another.

With the caterpillar season upon us or fast approaching, it might behoove us if we review the results of tests and observations made by cotton entomologists from across the U.S. cotton growing area. This group meets in the fall of each year and exchange information on insect management in cotton over a three day period. It has been one of my most important meetings to attend.

Table 3. Rating of insecticides for control of caterpillar pests in cotton.

Only Bollgard II provided top performance against fall armyworms. Of the available products, best bets were Tracer, Denim and Steward. Cabbage loopers were relatively easy to control with Larvin, Tracer, Steward, Denim and Intrepid. Bollgard II will also be good. Once Bollgard II is available in agronomically acceptable varieties, it will be the top selection for all caterpillar control. Something to look forward to if the price is right.

Table 4 provides data on the efficacy of caterpillar insecticides on other pests. Curacron had the most widespread activity, followed by Denim and Steward. Pyrethroids should never be used where aphids are a concern. Also Steward and Larvin should not be used where aphid infestations are increasing with moderate or greater numbers of ladybeetles present. These two insecticides are tough on these "beneficials".

Table 4. Rating of caterpillar insecticides for control of other pests.

 Table 5. Rating of insecticides for impact on natural enemies in cotton.

In fact, when considering the selection of a caterpillar insecticide and evaluating their impact on natural enemies, the information provided in Table 5 should be most helpful. Note that toxicity to natural enemies can vary greatly depending upon the species of "beneficial" that is present. For instance, Tracer has low toxicity to most predators but is highly toxic to parasites. This might be important if the Cotesia parasite is present in enough numbers to help on beet armyworm control. JFL

Overview. Growing conditions have generally been very favorable over the last week, with high and low temperatures generally near normal. Sunday's temperatures were somewhat higher than normal, and were in the upper 90s over most of the area. The crop is looking very good where moisture is not limiting plant growth. The PET network indicated that potential evapotranspiration over the last several days has averaged about 0.31 inches per day at Halfway and Lubbock, and about 0.37 at Lamesa. Heat unit accumulation per day averaged about 18.5, 20.0, and 21.0 for Halfway, Lubbock, and Lamesa; respectively (air temperature graph). Total heat unit accumulation from May 1 indicates that Halfway is at 742, Lubbock is at 860, and Lamesa is at 974. This translates into percentages of long-term average of +8, +18, and +18% for those locations.

Preliminary estimates of dryland cotton acreage lost to drought in the Texas High Plains are beginning to develop. Affected counties include Martin, Howard, Dawson, Gaines, Garza, Lynn, Borden, Cochran, Midland, Terry, and Yoakum. These counties normally plant approximately 1.2 million acres, and it appears very likely that some 800 thousand acres will not make a stand. If we add this to the 400 thousand or so we lost from various meteorological events, it appears that our acreage will be off some 1.2 million or so. If we planted 3.6-3.7 million in 1N and 1S, then our standing acreage is somewhere around 2.4-2.5 million at this time.

Important plant mapping data at early bloom are: 1.) Total 1st position squares present or missing (retained squares / total square sites = % square retention). Square retention goal is 75 - 85% 14 days after early bloom. 2.) Total 1st position bolls present and missing (retained bolls / total boll sites = % boll retention). Percent boll retention goal is at least 50%, with 75% excellent for 3 - 4 plants / ft on 40 inch rows. 3.) Nodes above white flower (NAWF) gives an indication of crop vigor and yield potential. For the High Plains region, greater than 7-8 NAWF could be considered excellent, 6-7 - good, 5 moisture stress evident, 4 or less - cutout imminent on determinate varieties.

It is recommended that pumping capacity be at least 2.5 gpm per acre if applications are made with low elevation spray systems in an average rainfall year. Irrigation amounts of not less than one acre-inch should be made in order to even minimally restrict evaporative losses.

Managing a crop with low water inputs and less than average rainfall will likely mean that the crop will finish earlier than normal. This could mean lower insecticide input costs and would necessitate early crop termination with less expensive harvest-aid products. RB

Sunflower (head) moth. We call this insect "the Boll Weevil of Sunflowers" to help communicate how important - and devastating - it can be. Pat Porter, Extension Entomologist at Lubbock, discussed control strategies in the June 15^th issue of FOCUS. For sunflower moth control, timing is everything, both in scouting and in treatment. Long-term experience suggests that if growers have trouble with sunflower moth, it is often because they sprayed too late. This is not an insect you can afford to be slow on. Data from the 2001 Extension hybrid sunflower trial in Hale Co. are listed below.

Table 6. Early blooming sunflower hybrids from Extension hybrid sunflower trial, Hale Co., Texas. 2001

Other confectionary and NuSun oilseed hybrids at the April 26 planting date have 2 or fewer days of bloom data as of June 28^th.

Further observations the week of June 15^th in the Texas South Plains suggest that sunflower may be blooming over a wider period of days this year, which may point to a lack of uniform germination and emergence. There appear to be 7 days or even more difference in head development with many fields with heads with well over 50% of the disk flowers in bloom versus other heads that have not opened yet. This complicates timing of sunflower moth spraying. We recommend that you focus primarily on earlier heads, which have the higher yield potential. This is normally the majority of heads. In most cases, it is not worth treating "stragglers" that are further behind in development. Growers that planted sunflower before early May should probably anticipate spraying sunflower moth twice, about 5 to 7 days apart. The second of these two sprayings should contribute significant control of sunflower moth to later developing heads. This issue of FOCUS presents two short videos that explain how to estimate percent bloom in sunflower and time insecticide applications.

Many earlier planted sunflowers began bud stage well over 3 weeks ago and thus are beyond peak bloom. Any irrigation during this time is highly beneficial and will continue to be so for about another two weeks. Sunflower irrigation termination occurs when the bracts on the back of the head fade to a lemon yellow color.

In a limited irrigation scenario where you may apply two mid-season irrigations, apply the first irrigation at bud swelling, 0.75-1.0" in diameter (R-3) and the second watering at full bloom.

Sunflower favor larger irrigations (2-4" per application) over frequent irrigation as deep percolation of water is still taken up by the deep-rooted sunflower. This also reduces the opportunity for disease development with fewer waterings and less humidity, particularly with sprinkler irrigation. Sandier soils of the Texas South Plains may not store all of the water in large irrigations, though if any crop can chase the water downward sunflower is it. Due to the limits of pivot irrigation in applying a limited amount of water per pass, growers should apply as much as they can without creating run-off or getting the pivot stuck. Due to soil cracking in 2001, pivot irrigation may be able to apply more water per pass than normal. The first watering may occur at bud with several subsequent irrigations including just before early flower and full bloom.

Full irrigation of sunflower may be considered from early bud to petal drop. Research data from the Southern High Plains suggest, however, that in many years optimal timely irrigation can perform just as well as full irrigation for sunflower. Sunflower will use as much water as is made available, but it is possible to overwater sunflower, especially during vegetative growth stages. This overwatering can hurt yields by creating a "rank" sunflower plant with fewer resources going to seed production. Such a plant also has a more shallow root system.

Bottom line for sunflower irrigation - Growers may have planned to limit water applications by timing to bud stage, bloom, etc. But if plants are wilted during the approximate 40-day period beginning with bud stage (and ending about 20 days after bloom), they are telling you they need water. We had not planned to water sunflower test plots in Hale Co. more than twice in 2001, but with the hot, dry weather we are accelerating water application.

Sunflower and hot, dry winds. I have observed some sunflower with leaves turning black, most often from the ground up. The unique thing is that the strong majority of the black, dead tissue is located on the south side of the plant, closer to the prevailing wind. A check of the sunflower disease resources and production guides (see http://lubbock.tamu.edu and select 'sunflower') suggest the symptoms are similar to verticillium wilt, but no yellow margin is found around the desiccated or 'burned' area. We note that leaves facing to the north and east are much less likely to be blackish and burned. We believe the condition showed up in early June in some fields that were underwatered. CT

Due to lack of planting moisture for most of the South Plains, a considerable amount of grain sorghum intended as primary acreage is not yet planted. Furthermore, areas around Lubbock and to the south and west are faced with waiting on cotton to zero out, before moving on sorghum, a real problem since insurance cutoffs are upon us. Drying soil conditions and the calendar are strongly influencing two key considerations for grain sorghum; hybrid maturity selection and seeding rate. Many growers, particularly for dryland sorghum, have preferred to plant a medium maturity hybrid about June 10-20. This places flowering after the worst of the summer heat with the prospect of September rains to assist grain fill.

In general, Extension suggests the following guidelines as criteria for the last recommended planting dates for sorghum maturity classes in the Lubbock region. Many growers across the northern South Plains need to consider shortening maturity for further plantings.

Table 7. Last recommended planting dates for sorghum maturity classes in the Lubbock region.

For more specific suggestions for individual hybrids, Extension has assembled "Last Recommended Planting Dates for Grain Sorghum Hybrids in the Texas South Plains - 2001", which is available from county extension offices or the Internet at http://lubbock.tamu.edu Seventeen different sorghum seed companies have suggested how late one may plant that company's own hybrids. Numerous early maturity hybrids are rated acceptable for planting as late as July 8^th to 15^th. Some maturities are in essence about 82-85 days to maturity. These hybrids certainly do not have the yield potential of a medium, but they can still produce favorable yields and generate winter residue cover for the 2002 cotton crop.

Many producers err on the side of planting too much seed per acre. As a result, in droughty conditions producers are at risk of inadequate moisture per plant during flowering and grain fill to produce grain. In managing risk, know that most grain sorghum hybrids at modest plant populations are able to flex upward to meet the yield potential of favorable conditions. This is less risky agronomically and economically than having a high plant population crop under droughty conditions.

For most dryland sorghum production in the Texas South Plains, when soil profile moisture is adequate (>4" of available soil moisture), a good target is 30,000-35,000 seeds/A. If soil moisture is low (2-4"), a seed drop of 25,000-30,000/A is advised. For any condition with poor soil moisture, especially as plantings approach July 1, consider seeding rates as low as 20,000 seeds/A. For limited irrigation (6-10") with low soil profile moisture conditions, target 40,000-45,000 seeds/A, but if soil moisture is good, consider 50,000-55,000 seeds/A. For full irrigation levels, target 80,000 seeds/A on June 1, but by July consider 100,000-110,000 seeds/A for non-tillering hybrids and 80,000-90,000 seeds/A for tillering hybrids.

Because seed costs are relatively low for sorghum ($1.00-1.20 cents per pound), growers too easily increase seeding rates as it doesn't much affect production costs. Growers should not let discount or replant seed prices dictate hybrid choice vs. careful selection of the hybrid that fits your needs.

One final note. Dr. Pat Porter indicates that on earlier planted sorghum fields, corn leaf aphids are relatively easy to find but greenbugs are not. CT

Things are fairly quiet right now. Most first generation European and southwestern corn borers have entered the stalk. Adults will begin to fly in a week to 10 days. Adult western corn rootworms began to emerge a week ago and may be abundant in some fields. One of the fields I was in earlier this week had 7 beetles per plant, and most of the adults had yet to emerge from the soil. Rootworm beetles will feed on leaves and pollen, but the main risk is from silk pruning. If green silks are pruned to within one-half inch of the shuck, there is a risk of poor pollination. A ballpark action level is 8-10 adults per plant at green silk. RPP

Warm, sunny days continue to drive high reference crop evapotranspiration (PET). Reference crop ET for this week at Lubbock was approximately 0.31 inches per day, which is also the historical long-term average value for this time of year. Spotty precipitation events have partially offset crop water demand at some locations, with rain gauges in the area indicating anywhere from no rainfall to 1.39 inches during the past week.

Some clarification of terminology may be helpful to users of the ET network data. Potential Evapotranspiration (PET) is a term long used to indicate the maximum expected (potential) water demand of a reference crop (cool season grass or alfalfa.) It is argued that the term "Reference Crop ET" (ETref), is less likely to be confused with the potential water use of a specific crop. Hence, "PET" is being replaced with "ETref" in many reports. Potential crop water demand is still estimated by multiplying this PET or ETref value by an appropriate crop coefficient (Kc). [ ETcrop = ETref X Kc ] DP

Table 8. Crop water use estimates (inches per week) for the week of June 21-27, 2001.

* Reference crop for these ET estimates is a cool season grass. Crop-specific ET estimates are affected by growth stage; ranges of values are presented for the reader's convenience and to accommodate the ranges of crop growth stages in the field.

Some individuals read the newspaper article this week that began with the headline, "Killer bees found in area but not in city". This might be a good time to explain the status of Africanized bees in the Southern High Plains. As of January, 2001, Africanized bees had been confirmed by the Texas Apiary Inspection Service to be in the following counties Gaines (1997), Dawson (1994), Borden (1999), Scurry (1999), and Cottle and King (2000). I have provided the official map here in PDF format.

A close look at the map would suggest that the bees are moving north at something like 30 miles per year. This is a very qualitative statement and is meant only as a generality. The point is that we may have some African/European hybrids in the area. Greg Jones, Extension Agriculture Agent for Garza County, called me last week with details of a bee attack that closely followed what would be expected from Africanized bees. It is now time to increase our vigilance and watch for aggressive bees.

Africanized bees, sometimes called "killer bees", look almost exactly like regular honeybees. It requires laboratory analysis to tell them apart. The practical difference between the two types of bees is that Africanized bees are very aggressive. In spite of what their popular name might imply, they do not fly around in swarms looking for people to kill. Rather, they defend their hives very aggressively when they perceive a threat. In hive defense they attack in large numbers. It is not uncommon for a person to receive 50 or more stings in an attack.

And this brings me to why I am devoting space in FOCUS to Africanized bees. People involved in agriculture inhabit most of the land area where we have not shown Africanized bees to be present, but where we suspect they will establish on their way northward. First contact then will likely come in an agricultural setting.

I have prepared a list of bullet points about Africanized bees. The most important of these are to become aware of bees in the areas you work and live, and treat all honeybees as if they had a few hundred friends to back them up in a fight. We can adapt to having Africanized bees, but we need to know something about them in order to do this. RPP