agriculture

We are entering a time when insects have become resistant to many of the Bt toxins in our GMO corn and cotton. This is the first in a series of articles where I will discuss what this might mean in terms of crop damage and the value of the Bt technologies.  To start the series, I want to make it clear that Bt crops are more than just insect protection; they are herbicide tolerance, cold tolerance, and improved genetics for yield, drought and disease tolerance. These other virtues remain even when the insect control fails, although reduced insect control clearly can affect some of them, like yield potential and drought tolerance.  Back in the early days of Bt crops, seed companies defined and charged a "technology fee" that was added to seed cost; growers knew what they were paying for insect protection. Those days are long gone, for various reasons, and now the seed cost is what it is and there is no way to know how much is being paid for the Bt traits.  While we don't kn...

It has been quite a challenging summer with our Bt crops on the Texas High Plains. This year we have seen huge numbers of corn rootworms emerging from many fields planted to mCry3a, a corn rootworm Bt toxin that has been used year after year in continuous corn. These fields had significant root pruning caused by rootworm larvae and produced a large number of adults � survivors of the toxin.  We have also seen corn earworm do significant damage to Bt corn that worked well a few years ago, and we have documented Bt cotton with unexpectedly high levels of bollworm damage and large larvae surviving the Bt toxins. In each case we collected insects from the field and sent them for laboratory assay to determine if the insects were resistant to the Bt toxins in the crops. These assays take time, but it is highly probable that in a few months we will be reporting that resistance has been confirmed in corn rootworm and corn earworm/cotton bollworm.  To help explain what is going on in n...

There were a crazy lot of western corn rootworm beetles emerging from continuous corn fields this summer in the Texas Panhandle, and with seed purchase decisions on the horizon it might be a good idea to talk about Bt resistance.  For two years now, Dr. Ed Bynum, Extension Entomologist in Amarillo, and I have seen extensive damage to Bt corn with the toxin mCry3a. These fields have been found in the zone from Dalhart in the north to Hart in the south.  We have been seeing all the textbook symptoms of a failed Bt rootworm toxin:  growers using soil applied insecticides in addition to their Bt seed, heavy root damage, plant lodging, lots of adult beetles on the wing because they were not killed as larvae feeding on roots, and aerial spraying of adult beetles to try and kill them before they clip silks or lay eggs that will become rootworm larvae the following year. This year we received phone calls from consultants around Hart that were alarmed at the huge numbers of beetle...

This is a jointly issued article from Extension Entomologists Drs. Pat Porter (Lubbock) and Ed Bynum (Amarillo). There are large numbers of corn earworm larvae in Bt corn ears in the Texas Panhandle, and some people are spraying in an attempt to control them.  The first question we are getting is what to spray, but the better question would be whether to spray.  Corn earworm is usually an ear tip feeder, and on its own is seldom an economic pest of corn. However, this year we are seeing earworms doing more than just tip damage, and feeding lower in the ear. The reason(s) for this change in behavior are unknown.  We have not forgotten last year though, when there was good evidence that just a little ear tip damage resulted in higher fumonisin levels. This could happen again this year, especially if the weather in August and September turns off wet and relatively cool. However, based on what we saw last year, the little bit of tip damage needed to promote fumonisin has alre...

I am glad folks are paying attention to what is happening in other areas. I had a few calls regarding bollworms this week--mostly in response to the hubbub in Central and South Texas. So far, worm pressure in cotton have remained light for the most part with some areas (e.g. parts of Swisher, Floyd, and Hale counties) just starting to show increase in numbers. Our Bt sentinel research plots at Texas A&M AgriLife Research and Extension center in Lubbock are showing a few worms in non-Bt plots�no activity has been spotted in any of the Bt technology plots so far. As the season progresses, we may see increase in moth flights and the egg lay. I wouldn�t spray for bollworm egg lay in West Texas cotton as very few eggs make it to worms (thanks to beneficials!). Treatment decisions should be made based on the amount of fruit injury and the presence of live worms in both Bt or non-Bt fields. Since newly hatched larvae must feed on the plant for the Bt toxin to be effective, delay decision ...

Kerry Siders, EA-IPM in Hockley, Cochran and Lamb counties, just reported that Danny Quisenberry, a crop consultant, found sugarcane aphids on older grain sorghum four miles north of Earth in northern Lamb County. Additionally, Greg Cronholm, a private crop consultant, just reported sugarcane aphids on sorghum in southern Castro County. Neither of these populations is at a treatable level, just small colonies on isolated plants at present. If this year's infestation pattern follows those of 2014-2017, then it is likely the aphids are already present in Hale, Floyd and Lubbock counties, although we have had no reports of this as yet.

This week's fall armyworm pheromone trap graph appears below. The 7-year average for this week of June is 110 moths per week. This week's capture was 707. This does not appear to be a phenomenon confined to the Lubbock Research Center, as Katelyn Kesheimer, EA-IPM in Lubbock and Crosby counties, reported several hundred moths in the Crosby County traps she operates. (Rain filled the traps so it was not possible to count all the moths, but there  were hundreds.) Additionally, Blayne Reed, EA-IPM in Hale, Swisher and Floyd counties, drove to Plainview from College Station late last week and reported that fall armyworm moths were very abundant at rest stops along the way. A prior post from April of this year discussed some genetic work being done by Ashley Tessnow, a graduate student in the Dept. of Entomology at College Station. She determined that the Lubbock area fall armyworm moths we sent her last year were 30% rice strain and 70% corn strain as a season average. She also no...