FOCUS will be posted on the Center web site on Friday afternoon. If you want e-mail notification when FOCUS or other items are posted on the web site, please let us know. As with anything new, there will be some growing pains associated with the change. Some of you may have trouble accessing or reading information available through the links provided. If so, please let us know and we will try to resolve these problems. Some readers of the printed version do not have direct access to the web site either because they don’t own a computer or maybe don’t use an internet service. Hopefully you will be able to access the electronic FOCUS by using someone else’s computer, perhaps at an agricultural business?

We have made a few changes in posting of county newsletters on the web. While many of you still prefer to get your newsletter in the mail, those who want it faster can now find it at either the Department of Entomology website (http://entowww.tamu.edu/) or at the Texas Pest Management Association website (http://www.tpma.org/).

As always, Pat and I and all other contributors to FOCUS wish you a successful 2000 growing season. We hope that in a small way we can be of benefit to you. JFL

• Virtually all cotton acreage planted by now
• Lack of subsoil moisture still a problem but recent rains have improved planting and stand establishment for cotton
• Roundup application window closing for earlier planted cotton fields
• Thrips evident in many cotton fields
• Early boll weevil trap catches down compared to previous 2 years
• Last year’s eradication program has significant impact
• Scattered infestations of beet armyworms found in cotton
• Early bollworm egg lay detected
• Watch for potential problems with grasshoppers, fleahoppers, plant bugs
• Mites still pose threat to corn
• First generation SWCB moth flight in progress
• Thrips damage to peanuts not a problem
• White grubs reported in some peanut fields

Thrips have caused damage to plants in many fields across the area. While this year is certainly not going to be one of our worst thrips years, this pest is still going to cause significant yield reductions where not handled properly. This tiny insect has moved out of maturing wheat and other alternate hosts and into young stands of cotton where it uses its piercing and sucking mouth parts to damage the undersides of cotyledons, very small leaf buds and squares in the terminal. Damage to cotyledons results in a silvering appearance on the undersides of these leaves with a speckled appearance. Pictures of thrips damage to cotton. Don’t confuse this with wind and blowing sand damage. Damage to leaf buds results in crinkling of margin tissue, and under heavy attack, leaves will be reduced in size, blackened and even killed. Damaged squares simply do not appear, being shed early in their development. It is the damage to leaves that catches the attention of most folks but it is the feeding on very small developing squares that results in yield reductions and loss of earliness. In our area, the short growing season does not allow sufficient time for recovery from early insect damage and square loss.

The most common species in this area is the western flower thrips, which is 1/15^th inch in length, straw colored and with wings as an adult. Pictures of thrips species. The immature stage is lighter colored, lemony yellow to white, without wings and very, very tiny. Development from an egg takes about two weeks, while the adult can live for as many as five weeks. Thrips can reproduce like aphids, requiring no mates and no egg stage. This greatly shortens generation time and allows for the rapid buildup of infestation levels. It is believed that open, warm weather allows plants to outgrow thrips feeding damage. While this may be so, more than likely it is the cold, damp, windy weather that encourages thrips to move from more open, non-yield threatening feeding positions, into the shelter of the terminal area where their feeding activity destroys squares and reduces yield.

The presence of thrips in a field does not necessarily mean there is a problem. The stage of plant growth, whether there is prior damage and whether thrips are mainly adults or immatures are important considerations. Our general rule of thumb is that control may be justified when the average number of thrips counted per plant is equal to or greater than the number of true leaves present. If just cotyledons (seed leaves) are present, the threshold is one. Once cotton reaches the squaring stage at 5-7 true leaves, thrips control is usually no longer needed. This is the time to back off and allow beneficial insects a chance to move back in the field and multiply.

There generally has not been heavy adult thrips numbers but often enough to trigger a treatment decision where an at-planting insecticide was not used. Immatures in much larger numbers have appeared in untreated fields this week, resulting in average counts of 7 or more per plant in two leaf cotton. Remember, the action levels that we generally use in this area are 1 thrips per plant for every true leaf present. Treatments are generally not warranted after squares begin to appear, at the 5-7 true leaf stage.

While the at-planting use of insecticides is by far the superior thrips treatment, some producers feel it is an unwarranted expense, especially in years when the cotton price is low and conditions are not very encouraging for good yields or low production costs. And some situations are also not particularly suitable for preventative treatments. This would certainly apply to dryland acreage. The Cadillac treatment is of course Temik, in the 2 to 3 pound per acre range. Higher rates are unnecessary and costly unless nematodes are a factor (see Terry Wheeler’s article). There are other soil-applied insecticides that are cheaper and effective but don’t net out as well. Seed treatments such as Orthene are also effective but don’t provide protection as long as the soil-applied systemics. We are again evaluating a new Novartis seed treatment, Adage.

Those of you that did nothing at planting for thrips management might want to carefully scout your cotton, dissecting out the terminal area in search of immatures. Watch out for adults that quickly fly off before you can count them. But be very cautious in counting the very tiny immature thrips that will be tucked away in the terminal and folds of leaves. Most folks under count thrips numbers.

Banded foliar sprays can be inexpensive compared to the broadcast applications. The only down side to banded sprays is that they are often not of a timely nature because of weather delays, wet fields and the slower rate at which fields can be treated with ground rigs versus airplanes. Remember, timing is everything! Don’t sacrifice yield to save application costs. Several insecticides are used for thrips control including Orthene, Bidrin, Dimethoate, Guthion and methyl parathion. While it may be convenient to combine a thrips spray with your Roundup application, waiting to apply the herbicide may be too much of a delay in controlling thrips. Base your decision on scouting reports. According to Monsanto, there is no compatibility problem between Roundup and any of the insecticides we use for thrips control.

Most preventative treatments play out in 3-4 weeks. Some may last longer in certain situations. It would be wise to check cotton that was treated at planting if only to make sure it continues to be protected up to the squaring period. Sometimes, dry conditions inhibit the uptake of soil-applied systemics, limiting their level of and length of residual control. Heavy rains can also leach these insecticides below the root zone, especially in the sandier soils. If at-planting insecticides are still working, there should be very few immatures present. Adults can be present, even in large numbers, but should cause little obvious leaf damage. Generally thrips numbers remain at or below one thrips per plant in fields where soil-applied insecticides continue to work during the pre-squaring period.

Recent heavy rains may have leached soil-applied insecticides out of the root zone, necessitating augmenting foliar sprays. These same heavy rains may have also removed the thrips that were present, leaving only the damage behind. Don’t treat these fields until you confirm there are enough thrips present to justify the cost.

Boll weevil trap catches are lagging behind the previous two year’s in spite of high winter survival based on the overwintering site survey, dig-up cage and emergence cage studies. We are catching 65% fewer boll weevils than last year (Table 1). See also Plains Cotton Growers web site for GRID maps and weekly trap summaries. Much of this reduction is due to the results of last fall’s diapause program in the three eradication zones that were activated. In active zones, trapped weevil numbers through week 22 have been reduced by 84% compared to last year while the two zones yet to start eradication (Northern High Plains and Southern High Plains/Caprock), trap catches have only been reduced by 24%. Way to go Texas Boll Weevil Eradication Foundation!

While trap catches are lower than expected, there will be enough weevils around to trigger treatments both inside and outside active boll weevil eradication zones. But problem fields could be more scattered than last year. Remember that those fields that square earliest or are planted closest to overwintering habitat are the prime targets of early colonizing weevils.

This could be a tough year for boll weevils. I don’t mean for producers but for boll weevils themselves. If conditions continue to generally be hot and dry, boll weevil mortality could be very high, especially prior to the closure of plant canopies in irrigated cotton. We have observed mortality to grubs in fallen squares as high as 90-98%. This year could follow the same trend we saw in 1998.

The winter was again mild resulting in excellent survival where moisture was adequate in the leaf litter. It was generally very dry in most overwintering sites and this dryness probably accounted for most of the overwintering boll weevil mortality observed. While early GRID trap catches are similar or lower than last year in zones yet to enter active eradication, This does not mean that this trend will continue. We may have a much-reduced level of suicidal emergence than last year. Suicidal emergence refers to those boll weevil adults that emerge and die before they can find, feed and lay eggs in squaring cotton. Weevils feeding prior to the availability of squaring cotton generally live an average of about 12 days, some less and some longer. Also, following a mild winter there is almost always an extended emergence, well into July.

The Foundation is making overwintered boll weevil treatment decisions at and just prior to the appearance of pinhead-sized squares. The logic behind this is that if you can find pinhead-sized squares then weevils can find the few matchhead-sized squares present and successful egg laying may have already commenced. I have no problem with making a treatment decision at the pinhead-size square stage---from a logistical standpoint. But an application that actually goes out to prevent egg laying into pinhead-sized squares is a waste of money better spent later. It takes about 7-8 days for a square to grow from pinhead-size to pencil eraser or 1/4" in size. Maybe 3-4 days for a pinhead-size square to reach matchhead in size. Application needs to be targeted toward when matchhead and larger squares will be present. This would mean making a decision to spray on one day and delaying the treatment for 2-4 days. This makes sense to me.

If you don’t have traps out on fields that had late weevils last year and your cotton already has two or more true leaves, you are already late, in some cases too late! I like to have traps established around fields two weeks prior to the week of squaring. The first week is to allow traps to get "settled in". The second week is your backup week just in case weather is poor the third week. The third week is the week when squares will appear and is the decision making week, unless weather conditions adversely affect trap catches forcing us back to using the 2^nd week of trap catches.

According to TAMU guidelines, if traps around a given field average 2 or more weevils per trap, at least one overwintered weevil spray is justified. (See publication: Boll Weevil Management in the Texas High Plains (http://www.plainscotton.org/guide98.html) I know many consultants that treated if they caught even a single weevil in any of the traps around the field. Why? Because we probably don’t put enough traps around fields to get an accurate picture of the overwintered weevil population entering the field. It is often better to error on the side of conservatism. This year may be different for some folks though. If you farm in an eradication zone, the Foundation will be spraying fields based on their traps (on wooden poles versus GRID traps on heavy wire poles) once pinhead squares appear. If you as a producer do not want ULV malathion applied to your field, you can opt to spray it yourself using an insecticide and rate listed in the recommendations of Texas A&M. You will need to spray twice with a 3-5 (4) day interval to satisfy Foundation requirements each time your field triggers based on trap catches. Why would you opt to do this at your expense rather than letting the Foundation spray? Maybe to save beneficial insects and perhaps avoid secondary pest problems such as beet armyworms or aphids. But---if you have to spray automatically twice even with a more selective insecticide, I am not sure if you have avoided the problems that might have been created by a single application of ULV malathion. It is your choice though.

The number of applications needed by producers outside of active eradication zones is determined by the amount of pressure exerted by the emerging weevil population, whether emergence is extended, and how deep your pockets are. Certainly, if you are catching numbers such as 10 or 20 per trap week as squaring approaches you should consider an automatic 2^nd application 5 days later. But what if you are catching 50, 60 or even higher numbers as squares appear? While there is limited research data available, I would suggest that you are no longer looking at delaying economic damage from weevils, you are in a fight to prevent it right now. This high a trap number is indicative of a level that will cause excessive square loss, much like that associated with heavy fleahopper infestations.

Overwintered boll weevil treatments are some of your cheapest applications. They can be your most important ones too. These can be banded on with a ground rig, cutting cost by up to 2/3rds. Later broadcast treatments are much more expensive. The only downside to these applications may be timeliness. If applications are not applied before pencil eraser sized squares are present, then weevils will gain entry to the field and all may be lost. Just don’t be late! Several materials are available including Guthion, endosulfan (Phaser and Thiodan), ULV malathion, methyl parathion, Penncap M, and Vydate. Vydate is favored by many because it is both efficacious and less prone to cause secondary pest problems. It also has the longest residual activity, after ULV malathion.

There has been some shifting of zone boundaries in recent weeks. Basically, the below Caprock portions of Motley, Dickens, Kent, Garza, Crosby, Briscoe and Armstrong counties are now in the Northern Rolling Plains Zone. Also, the western fields in Randall County have shifted into the Northwest High Plains Zone. But only those fields that were sprayed by the Foundation last fall will be in this year’s full season program. The remaining areas will link up this fall.

Before leaving the subject of boll weevils I would like to welcome Dr. Charles Allen back to Texas as the new Program Director for the Foundation. Charles was an Extension entomologist with Texas both in the LRGV and at Fort Stockton for a combined 15 years. He joined the Arkansas Cooperative Extension Service for four years before returning home. Charles has considerable cotton experience as well as boll weevil experience. He will be a worthy successor to Osama El-Lissy, who left for Washington, D.C.

A scattering of beet armyworm (BAW) infestations has been observed in several fields, especially across the southern acreage. This of course raises the warning flag, especially within an active eradication zone. Most BAW infestation in pre-squaring and early squaring cotton rarely amount to much. Hot temperatures without much shade and young cotton do not provide a favorable environment for BAW survival. We currently have several insecticides at our disposal that have efficacy against BAWs. These include: Larvin, Lorsban, Confirm and Tracer as registered materials and Denim and Intrepid as section 18 materials. The section 18 for Dupont’s Steward is pending before EPA. Pirate will not be available this year or in future years.

The newer BAW materials tend to be more expensive than the old standbys (but not always), but may also be more selective and efficacious. The older materials can be very effective, especially on small cotton. Coverage is critical for most of these materials. Use too little water or fudge the application and you will be sorry. More on BAW biology, sampling and economic thresholds next week.

Other pests to be on the lookout for include bollworms, cotton fleahoppers, plant bugs (plant bug drawings) and grasshoppers. There has been an increase in bollworm eggs in some fields in the Western High Plains eradication zone. This has nothing to do with eradication applications themselves but should provide a "heads up" to all that scout cotton. This is not necessarily early for our first small wave of bollworm activity. With cotton beginning to square, it is not too early to start checking for fleahoppers. Their numbers may start out low but could pose a problem in weeks two and three of squaring. Eradication applications may take care of some potential fleahopper problems but scout your cotton just the same. Don’t take chances. This pest along with 1-3 species of plant bugs found in the area can put a hurt to your early crop. IPM Agent Clyde Crumley has observed plant bugs in alternate hosts in Gaines County. So beware and be forewarned. I will cover more on fleahoppers and plant bugs next week. Also be aware that there is a growing grasshopper problem to the east of us in the Rolling Plains and central parts of Texas. With droughty conditions prevailing across the state, we may see more problems with grasshoppers later on.

While it is too early for problems with aphids in cotton in our area, producers can find comfort in the news that EPA once again has granted a Section 18 for Furadan 4F use in Texas cotton. We will need to activate our area for use following the same guidelines used last year. More on this later. Thus far, Furadan has been authorized for use in south Texas, the Coastal Bend area, the southeast and central areas of Texas. There have been problems obviously in these areas, much of it earlier in their growing season. We can only hope to avoid a major issues with this pest. We probably will not have Furadan available in 2001 according to sources within TDA. JFL

Greg Cronholm (EA-IPM Hale and Swisher Counties) reports that mite numbers are low, but thrips have been damaging young corn. He also stated that some fields have 30 - 50% of plants under attack by corn earworm (egg to 5^th instar), and fall armyworm is damaging up to 10% of plants in some fields. The good news is that beneficial insects are active and reducing larval numbers in some fields.

First generation southwestern corn borer (SWCB) moths have just begun to fly, so now is the time to scout for eggs and watch the trap capture data reported in county Extension newsletters. Greg Cronholm reports rather high SWCB moth captures in Hale and Swisher County traps. The first flight will last approximately three weeks and should peak around June 13-20, depending on temperature and location. (Photos of worm pests)

For those of you who run pheromone traps, especially consultants, you might be interested to know that Greg Cronholm, Johnna Patterson, and Cherinell Riley conducted trials last year of the three most common commercial European corn borer (ECB) lures. They found that the quality problems have been resolved and all of the lures are effective in capturing ECB. The full report is on our website .

Speaking of rain, I have received a few questions about its effect on SWCB and ECB. For the most part, rain is bad news for these pests, except in so far as it promotes healthier crops upon which to feed. Rain washes egg masses and small larvae from corn leaves, and I have seen a brief but intense rain event reduce egg mass numbers by as much as 90 percent. Fields with high egg mass numbers a day or two before a rain might not need to be treated after a rain. Moth numbers can also be reduced by strong rain.

Next week I will discuss Bt corn in some detail. For now it is sufficient to say that according to our research trails last year, you can expect extremely good borer control with Bt corn. RPP

It has been well documented in other peanut growing regions of Texas that thrips feeding damage does not significantly effect yields or grades. I have personally seen many fields that were experiencing damage which quite frankly looked pretty ugly, but those twisting curled leaflets were still doing their job of making food for the plant. In fact, the plants were not hurt when the damage was severe enough to cause leaflets to turn black or wither. Young peanut plants (35 days or less) have repeatedly been shown to tolerate over 75% defoliation without yield reduction or delay in maturity.

White grubs are being found at noticeable levels in a few area fields. At this point in time no observable damage is being experienced in our local crop which is normally characterized by white grubs feed on the secondary, or "feeder" roots of the plant, leaving the tap root intact. Plants appear to die of drought stress due to the fact that they simply don't have any hair roots left to draw water. In addition to seeing little root damage, I had a chance to send several specimens to the Texas A&M Entomology Department’s capable taxonomist, Ed Riley who identified this beast as a masked chafer grub. It turns out that this species is known mostly as a common grub pest of grasses but not associated with peanut in a pest capacity. CC

Well, here we go again. The cotton season is firmly upon us. March rainfall certainly helped get everyone in the mood for another production season, but early optimism began to wane as the realities of record heat, high winds and dry conditions were encountered in May. It appears that price prospects may be somewhat better than last year, but we still have a long way to go with the season.

We’re generally off to good start, but have experienced a few cold nights in the 40s from early to late May, but there is apparently not a lot of seedling disease around. Some fields exhibited problems with emergence. Many of these fields were planted in the high winds during the week May 15. The excessive drying conditions resulting from these winds (with up 47 mph gusts on May 17) sustained over several days, with humidity levels less than 10% certainly took its toll. Marginal moisture in some fields caused drying out of the seed zone. Center pivot irrigation was initiated to help with emergence problems, and once the winds and record heat ceased, and some rainfall was obtained, many of these fields achieved reasonable stands.

Our recent general rainfall across the region was fairly timely and helped many fields with critical moisture needs. Over the last week, amounts were spotty, but generally ranged from a few tenths to over 4 inches in some places. We were blessed by a reasonably good regional rainfall event, with virtually no hail - which is generally associated with May and June rainfall in the High Plains. Daily PET values are posted by the soil physics group (http://achilleus.tamu.edu/), and have ranged from about 0.20 to 0.35 inches per day for the last few days. Heat unit accumulation has been about 30-35% above the long term average for the total since May 1, mostly due to the record high temperatures we encountered in May.

Just as I was getting geared up for another 1998 dryland catastrophe, last week’s rainfall gave us a reprieve, at least in some areas. Much of the dryland acreage in Gaines, Dawson, and Cochran counties, and those southeast toward the Caprock is still fairly short on planting moisture. Due to the dry conditions, we are facing insurance deadlines (Table 2) for parched dryland fields, which missed last week’s rainfall. The planting progress over the last 3 weeks indicates that our irrigated crop was planted in a timely manner. The static planted percentages over the same period of time for some counties show that growers were not planting dryland fields until insurance deadlines approached (Table 3).

Before the recent rainfall, many producers were irrigating fields to assist emergence and stand establishment. Now might be a good time to assess the soil moisture situation in fields, and try to get somewhat ahead with irrigation while the crop is still relatively small. Dr. Bill Lyle (retired TAES Irrigation Engineer) indicated before the last rainfall events that it might be a good idea to get some water to the relatively low irrigation capacity fields. The thought process here might be to get some moisture into the profile before the high crop demand occurs. The relatively high surface evaporation incurred during mid- to late-May complicated irrigation management. Dr. Robert Lascano, TAES soil physics project leader, has developed a new PET software package called WinPET. This is a Windows software program that has utility in tracking PET and helping with irrigation decisions. The software is available for downloading at http://achilleus.tamu.edu/.

 Table 2. Final cotton planting dates for insurance purposes for the High Plains and surrounding region.

May 31	June 5	June 10	June 20
Armstrong	Cochran	Andrews	Mitchell
Bailey	Crosby	Borden	Motley
Briscoe	Dickens	Collingsworth	Scurry
Castro	Floyd	Dawson
Deaf Smith	Gaines	Donley
Hartley	Hale	Garza
Lamb	Hockley	Glasscock
Parmer	Lubbock	Gray
Randall	Terry	Howard
Swisher	Yoakum	Lynn
		Martin
		Midland
		Wheeler

Table 3. 2000 Southern High Plains Cotton Planting Progress.

The number of Roundup Ready acres planted are considerable again this year. Many growers are finding good value and easier weed management due to the Roundup Ready cotton varieties. The number of Roundup Ready varieties available in the marketplace also continues to increase, thus allowing more maturity types and a better fit for the various micro-environments and planting dates across the High Plains.

The Replant Relief program via the Monsanto TVP Rewards program continues to benefit many High Plains cotton producers. Replant Relief is available for the Paymaster stripper varieties, and varies as to whether one has a crop loss/destruct or crop loss/replant. Crop loss/destruct refunds per bag range from $30.20 to 31.20 for Roundup Ready varieties, are $71.00 for Bollgard varieties, and $101.50 for the Bollgard/Roundup Ready stacked gene types. Crop loss/replant refunds per bag range from $56.95 to 57.95 for Roundup Ready varieties, $97.75 for Bollgard types, and $128.25 for Bollgard/Roundup Ready stacked gene varieties. Paymaster varieties covered by the program include PM 2145RR, PM 2156RR, PM 2200RR, PM 2326RR, PM 2379RR, DP 215B, DP 237B, PM 2280BG/RR, and PM 2326BG/RR. The program provides a refund on the technology fees and seed costs, and is only valid for losses occurring within 60 days of planting. Claims must be reported to local Monsanto or Paymaster representatives within 10 days of crop loss AND before crop destruction. All claims must also be submitted before August 31, 2000.

Although several glyphosate-based herbicides are marketed and can be used on Roundup Ready cotton, Monsanto literature states that to be eligible for TVP Rewards and Replant Relief, labeled Roundup brand herbicides are the only systemic, non-selective herbicides that may be used for burndown or in-crop applications on any Monsanto technology crop. The only Roundup herbicide brands that Monsanto will label and promote for over-the-top (OT) use on Roundup Ready cotton include Roundup Ultra and Roundup Ultramax.

Other glyphosate materials authorized by Monsanto for OT use in Roundup Ready cotton for the 2000 crop season include: Roundup Ultra, Roundup UltraMax, Buccaneer, Honcho, Mirage, Rascal, Rattler, Silhouette, Credit, Glyfos X-TRA, Gly-Flo, Glyphomax, and Glyphomax Plus. A prepackage of Staple and glyphosate called Staple Plus is now available from DuPont. According to DuPont literature, this system is fully labeled by EPA and is authorized by Monsanto for use on Roundup Ready cotton. Remember that use of any glyphosate material other than Roundup Ultra or Roundup UltraMax in Roundup Ready cotton eligible for TVP and Replant Relief programs will void participation.

Please consult your chemical sales or distributor personnel for more information concerning these products. Monsanto literature states that "Monsanto does not make any representations, warranties or recommendations concerning the use of glyphosate products manufactured by other companies which are labeled for use in Roundup Ready crops. Monsanto specifically disclaims all responsibility for the use of these products in Roundup Ready crops. All questions and complaints arising from the use of glyphosate products manufactured by other companies should be directed to the manufacturer of the product in question. Furthermore, this product may not be labeled for this application in your specific state. Please contact the manufacturer of the product for confirmation that this is an approved application."

Over-The-Top Roundup Application Window

As we move into the first week of June, a lot of early planted fields are nearing the end of the OT Roundup Ultra application window. Keep in mind that one has to target crop stage for OT Roundup applications in Roundup Ready cotton. Proper staging for termination of the OT applications is important, as late applications can result in poor early season fruit retention - exactly what we DON’T want in our short season environment. We haven’t observed much "ragging" of the crop across the region as of this writing, but if the first mainstem leaves are lost due to environmental damage, it becomes very important to count mainstem nodes to determine proper staging. A node is a bump or knot on the mainstem where leaves, vegetative and fruiting branches arise. The nodes at the bottom are called cotyledonary nodes because the cotyledons, or seed leaves are attached there. The two cotyledons are always opposite one another. Always count this as node zero. Then begin counting up the mainstem until 5 nodes are found. This is where the 5^th true leaf is located. Once the 5^th true leaf reaches 1" (or about the size of a quarter) the OT window has closed for the Roundup Ready varieties. If the leaf has been lost, then it is important to count the mainstem nodes. Pictures for staging termination of the OT applications.

Roundup Use Guidelines

Best control is generally obtained from Roundup Ultra when most weeds are 1 to 3" in height. Up to two 32 oz/acre of OT applications of Roundup Ultra can be made to Roundup Ready varieties. At least 10 days between applications and two additional mainstem nodes of growth are required. No single application may exceed 32 oz/acre. Once past the four-leaf stage, two post directed or shielded sprayer applications can also be made, at a maximum 32 oz/acre per application. Ten days and two additional mainstem nodes of growth are also required between these applications. Follow up applications of up to 64 oz/acre can be made OT again once 20 percent boll crack has occurred to control late season or perennial weeds. The maximum amount of Roundup Ultra that can be used OT and through lay by is 4 quarts/acre, while the seasonal maximum is 8 quarts/acre.

Research conducted by TAES weed scientists Dr. Wayne Keeling and Dr. Pete Dotray indicates that the addition of a half-rate (0.6 oz/acre) of Staple herbicide to the first OT application of Roundup Ultra may enhance control of several weed species and also provides some residual control. The DuPont Staple label should be consulted for specifics. Improved control of some morning glory species and palmer amaranth is stated. Rainfall or sprinkler irrigation (0.5 to 1") after application is required for residual control.

Ammonium sulfate is generally necessary when preparing Roundup Ultra spray mixtures in West Texas due to our "hard" water. The general recommendation for Roundup Ultra spray mixtures is to add 17 lb. of spray grade ammonium sulfate/100 gallons of spray.

In some environmentally sensitive areas such as near conventional cotton, or differing transgenic varieties or crops, towns, farmsteads, etc., drift control becomes important. Proper selection of spray tips can help reduce drift. Tips such as Turbo TeeJet wide angle flat spray tips generate larger droplets which results in less drift potential. Tips with wider spray angles, such as 110 degree, vs. 80 degree fans allow the spray boom to be placed somewhat closer to the target and can also be beneficial. There are several drift minimization agents available. The merits of such products may be debated and although pricey, these materials may warrant investigation where drift is a concern. Materials such as Strike Zone and Drive have ammonium sulfate included.

 Buctril 4EC on BXN cotton

Buctril 4EC is a herbicide that offers good control of many broadleaf weeds, as long a size is not an issue. Targeting small weeds is critical. With the BXN weed control system, one needs to remember to stage the weeds and not the crop. When the 3/4 pint/acre rate is used, most weeds should be 1-3 inch tall. If the rate is increased to 1 pint/acre, then weeds can be 1-4 inches tall. Consult the label for specific weeds and sizes. In general, morning glories should not be larger than 3-4 inches at application. Pigweeds should not exceed 1-2 inches in height. Sequential applications may be required for control of some weed species. When high densities of weeds are encountered, make sure excellent coverage is obtained. For best results, broadcast applications using 15-20 gallons per acre total volume are recommended by local Aventis personnel. Use nozzles that provide good coverage such as flat fans. Including a refined crop oil at 0.5% to 1.5% of the total spray solution (2-6 quarts/100 gallons) should increase weed control.

When fields require a graminicide for grass control, the Buctril 4EC label states that if Buctril is applied first, wait 7 days before applying Assure II, Fusilade 2000, Poast or Select. When the grass herbicide is applied first, wait a minimum of 3 days before applying Buctril 4EC. Due to herbicide antagonism problems, grass control may be reduced if Assure II, Fusilade 2000, Poast or Select are tank mixed with Buctril 4EC.

According to the DuPont Staple label, Staple can be tank mixed with Buctril 4EC for use on BXN cotton. The Staple rate should be 0.8 oz/acre plus 1 pint/acre of Buctril 4EC. Improved control of various pigweed species can be obtained. Rainfall or sprinkler irrigation amounts of 0.5 to 1 inch are required to obtain residual control. RB

To estimate potential evapotranspiration for a particular crop (crop PET) from the reference PET, we multiply the reference PET by a crop coefficient (Kc). The crop coefficient is specific to the crop and will change with growth stage. For instance, the reference PET at Lubbock for the week of May 31 to June 6, 2000 was 1.37 inches. The potential water demand for cotton in the seedling stage (Kc = 0.07) was 1.37 X 0.07 = 0.10 inch. For corn at a 6-leaf stage (Kc = 0.85), the water demand was 1.37 X 0.85 = 1.16 inch. For corn at an 8-leaf stage (Kc = 1.0), the water demand was 1.37 X 1.0 = 1.37 inch. These values have been calculated and summarized in table 3 below.

Crop coefficients by crop and growth stage are located on the Texas ET Website.

High Plains Corn - http://texaset.tamu.edu/include/crop/corn.html

High Plains Cotton - http://texaset.tamu.edu/include/crop/cotton.html

High Plains Sorghum - http://texaset.tamu.edu/include/crop/sorghum.html

Other Crops - http://texaset.tamu.edu/include/crop/cropcoe.html

Turf - http://texaset.tamu.edu/turf.asp

Table 4. Potential Evapotranspiration (PET) Update. From the South Plains PET Network, May 31-June 6, 2000:

** PET values for crops are estimates based upon High Plains crop coefficients. PET will vary with growth stage, which is affected by cumulative growing degree days (heat units).

PET data and weather data for Halfway, Lamesa, Lubbock, and Seminole are available from the Southern High Plains PET Network at: [http://achilleus.tamu.edu/data/data.html].

The Northern High Plains PET Network (http://amarillo2.tamu.edu/nppet/petnet1.htm) contains detailed PET estimates by crop and by planting date for the following locations: Bushland, Dalhart, Dimmitt, Earth, Etter, Farwell, Morse, Perryton, Wellington, and White Deer. Current data are available at (http://amarillo2.tamu.edu/nppet/station.htm).

Many producers err on the side of planting too much sorghum seed per acre. As a result, in droughty conditions, producers are at risk of inadequate moisture during flowering and grain fill to produce grain. Pay close attention to seed size of the variety you select. To approach optimum results do not neglect planter calibration and know your sorghum seed size (typically 13,000-16,000 seed/lb.). In managing risk, know that most grain sorghum varieties at modest plant populations are better 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.

Managing risk--balancing sorghum seeding rate vs. available soil moisture: For most dryland sorghum production in the Southern High Plains, when soil profile moisture is adequate, a good target is a seed drop rate of 30,000-35,000 seeds/A (thus a slightly lower plant population). If soil moisture is low, a seed drop rate of 25,000-30,000 is advised for later plantings approaching July 1, with poor soil moisture, consider only 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 varieties and 80,000-90,000 seeds/A for tillering varieties. Keep in mind that these guidelines translate into low pounds per acre seeding rates. 30,000 seeds per acre is essentially 2 lbs./A--and no more--for a typical size sorghum seed.

As a conservative and easy to remember rule of thumb, a sandy to sandy loam soil is capable of storing about 1.0" of available soil water, a silty loam to clay loam about 1.5", and a clay soil about 2.0". Soil moisture storage capacity will increase for a course sandy soil if subsoil layers are finer textured. Shallow caliche layers will limit moisture storage capacity. Recent rains will probably not contribute to any significant soil moisture below 18 to 24" depth. That soil moisture is important for sorghum production as 1" of available soil moisture translates into about 350-400 lbs. additional grain yield. CLT

Nematode density is lowest in the spring and generally highest in September and October. In the spring it can be difficult to determine whether a field has a high or low population of root-knot nematode, or even any nematode problems at all. It is risky to use spring sampling to manage nematodes. Fall sampling provides a much better estimate of which nematodes are present and whether their density is high enough to require management. Nematode management can be expensive, so it is important to have good representative samples to base decisions on. Poorly taken samples or insufficient numbers of samples can result in expensive mistakes!

The southern root-knot nematode is the primary nematode problem on the High Plains of Texas. Management options generally fall into one of these categories: chemical control (fumigants or nonfumigant nematicides), crop rotation with a nonhost of the nematode, and nematode resistant varieties. We do not currently have varieties that are adapted to the High Plains which are root-knot nematode resistant for cotton, potatoes, corn, sorghum, sugar beets, watermelon or any other commonly grown crops. Peanut is the only crop commonly grown in this region, which is a nonhost for the southern root-knot nematode. The peanut root-knot nematode (Meloidogyne arenaria) and northern root-knot nematode (M. hapla) have not been identified in this region, primarily because they do not reproduce on cotton. Fields that have been in long-term vegetable rotations are more likely to have a mixture of root-knot nematode types than those that are based on cotton. Chemical control is based on a very short list of products. All products must be applied at or before planting to the soil to be effective.

Future issues of FOCUS will address sampling procedures and management guidelines for nematodes. New projects addressing sampling and treatment of nematodes will also be discussed. TW

The bee lab at College Station provides a free identification service, but this requires some effort on the part of the person submitting the suspect bees. The process is detailed at this link (http://lubbock.tamu.edu/Lubbock/ipm/Urbanweb/people/honeybee.html). College Station maintains an Africanized bee website [http://agnews.tamu.edu/bees/] that answers many common questions about this serious pest. RPP

Focus on Entomology is published by the Texas Agricultural Extension Service Route 3, Box 213AA Lubbock, TX 79403 For more information call or e-mail: 806-746-6101 or m-coffman@tamu.edu Editor: James F. Leser Web Site Layout: R. Pat Porter Production: Michelle Coffman Educational programs conducted by the Texas Agricultural Extension Service serve people of all ages regardless of socio-economic level, race, color, sex, religion, handicap or national origin. The information given herein is for educational purposes only. References to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Cooperative Extension Service is implied.