High Plains weather has continued to play "search and destroy" with our cotton crop.  The result of this onslaught has been the loss of thousands of acres and the reduced health and vigor of much of the remaining acreage.  How is this factoring in with our insect situation? Thrips numbers have been dramatically reduced by high winds, blowing sand, hail and driving rains. But with plants suffering from leaf damage, possible root health issues and previous thrips damage, any remaining thrips infestations may be doubly troublesome.

Since thrips cause most of their yield impact by feeding in the terminal, the absence or reduction of suitable feeding sites on previously expanded leaves will force thrips into the terminal area and exacerbate the situation.  The return of warm weather may help the situation but plants may be slow to respond to this improved weather if their health has been diminished.

We checked our thrips control test at Lariat on Monday after being kept out of the field by weather for four days.  Thrips counts were down but still above threshold in untreated plots or where at-planting treatments were playing out.  Plants were putting out their 3^rd true leaf with untreated plots averaging 6 thrips per plant.  The Cruiser seed treatment counts were ranging between 4.3 to 6.4 thrips per plant.  Temik treated plots were averaging between 1.9 to 3.1 thrips per plant.  These numbers were close to or exceeding our threshold of 1 thrips per true leaf present, but for the most part, reproductive recruitment had not become a factor. 

We have two treatment entries where we will over-spray one of the Temik or Cruiser seed treatments with Orthene if the threshold is exceeded.  But remember that a follow-up spray can only be triggered if immature numbers approach 30% of the total count. The 3.5 lb. rate of Temik averaged 5.5% while the Cruiser seed treatments averaged 15.0%.  We sprayed the designated Cruiser plots because total thrips averaged 4.9 per plant and percent immatures averaged 17.3.  We went with a lower immature percentage threshold (target threshold is about 30%) because of the reduced health of plants and previous damage.  So far this test would indicate that Temik at cost competitive rates is lasting longer than the Cruiser seed treatment.

The foliar Orthene treatment we applied on May 25 was still holding up with total thrips averaging 2.4 per plant and only 7.2% immatures.  This was down from 12.3 total thrips per plant before we treated when the threshold was 1 per plant. 

Now how much has weather affected the thrips situation? Last year's test saw a 300% increase in total thrips numbers from 14 days after planting to 21 days following planting.  This year's test saw a 57% decrease in total thrips numbers from 14 days after planting to 27 days after planting.  Immatures were also much higher last year than this year.  This should indicate the level of thrips impact that our recent severe weather has had on thrips.  This would vary, depending on your location and weather situation but the Lariat site has avoided most of the really bad weather so far.

I believe that most of the thrips population reduction probably occurred with the winged adults and to a lesser extent the immatures.  Wingless immature thrips tend to be "tucked away" in more protected areas of the plant than adults.  Thrips have been moving from other hosts, especially maturing wheat, since April.  How much of this movement remains is unclear.  However, by this time in the season, the re-infestation of surviving cotton fields or those that will emerge later from replanting decisions will probably be a low risk.  Most of the thrips infestation increases will be from resident populations in surviving fields.

I would not recommend using an at-planting insecticide treatment for cotton planted or replanted this late.  I would instead rely on scouting and spraying those few fields that need help with Orthene, Acephate, Bidrin or Dimethoate. Base decisions on total number of thrips per plant and the number of true leaves present (even those that have been damaged).  The uppermost leaf counted must have started to unfurl.  Also add percent immatures to the equation.  I would be much more aggressive on surviving cotton that has suffered from previous weather and thrips damage.  This would include lowering the threshold a bit and also the percent immature target.

We've seen very few other pests lately except a few beet armyworms and continuing grasshopper problems. If previous experience holds up then these early beet armyworms will fail to amount to anything.  Trap catches remain low compared to historical records from bad beet armyworm years.

Beneficial insects and spiders are also scarce.  I have seen a big-eyed bug or two, a few minute pirate bugs and one or two spiders---but that is it.  Predator numbers are way down so far this year. I am concerned.

There are some fields that have begun to square.  These need to be scouted for square retention and for both Lygus bugs and cotton fleahoppers.  Nothing serious has been reported thus far.  This is mostly a "heads up" for those of you that are "ahead of the curve".

The boll weevil situation has at least been a blessing.  Light trap catches continue to indicate low numbers of weevils survived the winter.  This was mainly due to the efforts of the Texas Boll Weevil Eradication Foundation (TBWEF) in conducting a highly successful program last year.  They have yet to spray any fields in the High Plains.  No weevils have been caught so far in the Northwest Plains Zone with no weevils caught in recent weeks in the Northern High Plains, Southern High Plains/Caprock and Western High Plains zones. A few weevils continue to be caught in the Permian Basin Zone, a reflection of the problems incurred last year.

Recent weather has continued to dog the efforts of the TBWEF. Access to fields and traps lost to weather and sand fighters have been serious problems.  I know it is imperative that producers get across their fields as quickly as possible, either to sand fight or replant, but those traps you are knocking down are taking away our ability to track the boll weevil and make any kind of sound management decision.  Traps on the ground do not catch many weevils and when weevil numbers are as low as they are right now, we need every advantage we can get to detect their presence.  The foundation has tried to keep traps out of the way and at lower heights so that equipment can clear them, but sometimes it just doesn't work out.

Please help us out as much as you can.  The high rate of loss of traps recently is also taxing the available supply and the ability of trappers to replace traps in a timely manner.  We need these traps. They are our eyes for seeing the boll weevil situation.  As chair of the Technical Advisory Committee of the TBWEF, I am pleading with you to help us out. As more fields begin to square, these traps will become critical to the continued success of the program.

Failed cotton acres will pose another problem to the TBWEF.  Last year trap numbers on failed acres in the Dawson County area were greatly reduced when cotton failed to emerge due to dry conditions.  Unfortunately, once these fields were planted back to a grain crop and it rained, cotton emerged along with the grain crop.  This was generally not detected and the reduced number of traps failed to catch the movement of weevils into these fields where they then reproduced and produced larger numbers of weevils.  This cannot happen again this year.  Producers must make sure that no cotton emerges in these failed fields that are not replanted to cotton.  Otherwise their 2003 assessment will stay in place to cover the costs of needed spray operations.  With the shortage of traps, the foundation will need to make hard decisions on how to handle these possible failed acres in the next few days.  When weevil numbers are down as low as they are right now, we cannot afford any hiccups at this time.  JFL

How much cotton is going, going, gone?  Since I promised to get more information on the ongoing crop losses in last week's newsletter, I have diligently worked to get together some information.  Unfortunately, to date, no firm data are available, but the disaster numbers are beginning to take shape.  Of course, as they say in the military "the situation is in flux" and more cotton continues to go down on a daily basis since hot conditions have recently returned to the region. 

With the potentially large acreage of cotton lost to recent severe weather and the likelihood that many thousands of these acres being replanted to crops other than cotton, I would expect producers would have many questions on variety selection, agronomic management issues and potential insect and disease problems they might face. Dr. Calvin Trostle, Lubbock Extension Agronomist, is an excellent source for this information but unfortunately I have not been able to tie him down long enough to write something for FOCUS.  You can go to the June 21, 2002 issue of FOCUS and see what he said then and also to get his reference web site links.  Likewise there will be questions pertaining to current and potential pest problems with these alternate crops.  Dr. Pat Porter, Lubbock Extension Entomologist, will handle questions in this area.  JFL

Crop water use.  Evapotranspiration (ET, crop water demand) estimates for the South Plains are accessible on the South Plains ET Network website at: http://lubbock.tamu.edu/irrigate/weatherdata.html.  Texas Panhandle and South Plains ET estimates are accessible on the North Plains ET Network website at: http://amarillo2.tamu.edu/nppet/station.htm.   Some of these estimates are summarized below; crop water demand estimates for additional crops are available from the networks.  These crop water demand estimates reflect expected maximum water use for well-watered (non-stressed) crops.  

One of several current Lygus projects underway is a survey to identify the non-cotton host plant sequence prior to cotton planting and to establish the relationship between non-cotton host plants and Lygus migration to adjacent cotton.  In 2002, Lygus surveys were conducted in mid- to late April in each of the 25 counties of the PCG service area.  The standard sweep sampling method was used to survey prominent weed hosts along roadsides. A total of five locations were surveyed per county.

In an effort to establish a host plant sequence of Lygus movement from wild habitat to cotton, surveying was continued at a 4-week interval in Hale, Lubbock, and Gaines counties. This represented the northern, central, and southern regions of the 25-county PCG service area.

All 25 counties were again surveyed in late July to coincide with cotton blooming/fruiting.  The last survey was conducted in early September, coinciding with boll maturity. A season total of 67,330 sweep samples were taken from non-cotton hosts, with a survey sequence of mid-April, mid-May, mid-June, late July, and early September. 

All 25 counties were also surveyed for cotton infestations in late July.  Cotton survey sites were adjacent to the non-cotton survey sites.  A second survey was conducted in cotton in Hale, Lubbock, and Gaines counties in early September. A total of 33,015 sweeps were taken from cotton.  We will be repeating the survey for 2003 with the same survey protocol as in 2002.

In 2002, Lygus bugs were recorded from 26 of 28 non-cotton host plants that were sampled along the roadside.  Lygus species identification has not been completed, but it appears that L. elisus and L. hesperus are the two dominant species in the Texas High Plains Lygus complex.  The mid-April survey showed that wild mustard, redstem filaree, and alfalfa were the dominant hosts that supported Lygus bugs.   When mustard senesced and alfalfa began to bloom in mid-May; alfalfa, yellow sweetclover, woolyleaf bursage, prickly lettuce, curly dock, Russian thistle, field bindweed, broomweed, ragweed, pigweed, and gaura supported Lygus populations. 

The mid-June survey indicated that alfalfa and yellow sweetclover were still the dominant hosts prior to cotton squaring, while Russian thistle and wild sunflower supported a significant population in areas where alfalfa was not very lush.  In late July, overall Lygus numbers in wild hosts declined, with alfalfa, pigweed, Russian thistle, and silverleaf nightshade supporting a small number of Lygus. 

In early September, alfalfa continued to be the most attractive host for Lygus.  Lygus abundance in cotton was 0.5 adults per 100 sweeps compared with 2.5 per 100 sweeps in alfalfa in late July.  Lygus abundance in cotton remained the same from late July to early September, when alfalfa became more attractive for Lygus.  Preliminary data suggest that in the Texas High Plains a host sequence exists for Lygus to move from non-cotton hosts to cotton and back to non-cotton hosts during the year.

The 2003 survey began in late January and we have obtained and processed 35,870 sweeps as of May 30.  Lygus numbers in the wild hosts have been relatively higher this year compared to last year across all hosts.  However, we cannot predict at this time whether the high number of Lygus on roadside weeds will actually result in a higher number of Lygus in cotton this summer. MP

I will discuss a few of the research projects I am involved with in the area. In a joint project with Monti Vandiver (Pest Management Agent in Parmer and Bailey counties), New Mexico State University, and West Texas A&M University, we are once again screening corn earworm (cotton bollworm) adults for increased tolerance to some insecticides. The focus of this study is for vegetable crops attacked by this pest.  We did this last year in the Farwell, Oklahoma Lane, and Lazbuddie areas and found strong evidence for increased tolerance. Our local work and performance concerns from local crop consultants stimulated a large group of Extension cotton entomologists to initiate a statewide survey for pyrethroid resistance. Our concern is for control of bollworms in cotton and earworms in green beans. Incidentally, Allen Canning Company has increased the contracted acres of green beans. This year they will contract about 9,000 acres, which is a significant jump from the 7,500 acres last year.

Greg Cronholm, Pest Management Agent in Hale and Swisher counties, Monti Vandiver, and I will be collecting European and southwestern corn borers for shipment to the University of Minnesota where they will be screened for possible resistance to the toxin present in Bt transgenic corn. We have done this for several years and the latest results show that some of our European corn borers have the gene that gives them resistance to Bt. Specifically, the allele (gene) frequency was shown to be 0.021 with a 95% probability of detection. I will be glad to send the scientific article to anyone who is interested, but the practical finding is that yes, we do have resistance genes present locally. Refuge rules for Bt crops are meant to slow the development of resistance, and we now know for sure that the threat of resistance on the High Plains is real.

Brad Lewis (NMSU at Las Cruces) and I will be conducting some spider mite control trials at the NMSU Research Center north of Clovis. We are looking for new miticides that could replace or augment Capture (bifenthrin). Robert Bowling, Pest Management Agent in Moore County, headed a mite-screening project last year. Many of us participated in the effort. Robert found up to a 7,000-fold increase in tolerance to Capture in some mites north of Amarillo. He also found slightly elevated levels of tolerance to dimethoate, but nothing higher than 14-fold. Both of these numbers are as compared to a susceptible strain of mites that Brad Lewis brought us from Las Cruces, NM. PP

The Texas A&M University Entomology Department and the Texas Cooperative Extension have launched a new internet web site that pulls together all web-based IPM information available through the TAMU system into one location.  The site can be accessed at http://txipmnet.tamu.edu.  This site will offer visitors an array of IPM topics pertaining to various agricultural commodities, ornamentals, lawn care, greenhouse and much more. The site will also provide links to other information regarding such topics as plant pests, diseases, herbicides, harvest aids, varieties, etc.  JFL