July turned out to be troublesome for Alabama cotton producers

Tag : cotton
Early this season, grasshoppers were very abundant in Alabamacotton, and they posed a potential problem until cotton reachedabout the fifth true-leaf stage, he says. Thrips were not as badas they have been in some years. Some of this was due to the factthat there were some rainstorm events during that window. It hasbeen my experience that rain will drown immature thrips and that agood, hard-driving rain is about as good as a foliar spray, saysSmith.
All of the thrips control growers have available to them atplanting are somewhat equal in performance, he says.
Some look better at times than others. But under heavy pressure,all of them would benefit from supplemental foliar controls, saysSmith.
Growers saw plenty of adult tarnished plant bugs in June, says theentomologist. But in my opinion, the square loss did not correlatewith the number of adult plant bugs we saw, and even though theywere in the field, a lot of the fields remained what I would callabove the threshold level as far as pinhead square set, he says.
Aphids are another insect pest in that same window, says Smith.They built slowly, and they were slow to die off from the naturallyoccurring fungus, he adds.
July, he says, turned out to be troublesome for Alabama cotton producers. We had a major tobacco budworm flight and the wormsfrom that flight for about the first two weeks of the month.Beginning on about July 18 or July 20, we had a major bollwormflight, but the larvae didnt cycle out until about the first weekin August.
We dont know where these tobacco budworms came from, but therewas a generation that caused heavy foliage loss to peanuts inAlabama and Georgia during the month of June. We werent smartenough to know it was going to translate into heavy pressure oncotton. It could be that were influencing these worms to somedegree as we rotate or shift these crops around from cotton to cornto soybeans and other things. Im not sure this is the answer. Ivetalked with other entomologists in the Southeast, and none of ushas a clue where these tobacco budworms came from, he says.
Smith says he works on five different experiment stations inAlabama, with one being in southeast Alabamas Wiregrass region.On July 3, in the Wiregrass, we stepped out of our vehicles and wesaw tobacco budworm moths in cotton like we hadnt seen in severalyears. We went back the next week and saw one and two-day wormseverywhere, so we immediately started our own tests, he says.
Research documented a few days later showed that pyrethroidsapplied to these tobacco budworms was about like spraying waterinto a high level of resistance, says Smith. That left us withTracer  which was in short supply  and Spirit  which is about$15 per acre. In general, conventional varieties in my plots and ina lot of other places took heavy damage.
On about July 20, he says, the pressure seemed to slack off, butthat was because the bollworm moths that were depositing their eggsdid it down in and on the white bloom.
Those worms were  in a lot of cases  five to seven days old whenwe detected them, and this means even the pyrethroids didnt do avery good job of cleaning them up. I along with the people withwhom I work miss this generation every year. Im convinced that noone can accurately scout for that July 20 bollworm generation thatcomes off of corn and into cotton.
The only way to handle that population, he advises, is to make anautomatic spray of a pyrethroid on about July 20, and this wouldhold true for conventional cotton as well as some of thegenetically altered varieties.
You could move that July 20 date forward or backward a day or twodepending on the weekend. But every year, were usually too late.Another big factor in this damage that we got from this generationof bollworms was that where sprays had been made in recent weeksfor aphids, tarnished plant bugs or whatever we were spraying for,the beneficial were not found and the worm damage was about four tofive times as heavy as in fields where beneficial were present.
I would suggest in future years, that if were plantingconventional cotton, and we have any reason to suspect we mighthave a bad worm year coming, that were just going to have tooverlook all bug damage prior to about July 20, and keep allbeneficials present until that date.
This also applies to single-gene cotton like Bollgard and thedouble-gene cotton like WideStrike and Bollgard II, he says.Measurable damage was seen where those varieties were planted, headded.
You could visibly see worm damage in just about everything thisyear, says Smith. We estimate that varieties like DPL 555 giveabout 60 percent bollworm control. Beneficials give us another 20to 30 percent control if theyre present. This leaves about 10percent escapes, and thats what we had. When there are nobeneficial present, we get about 40 percent of the worms emergingon the single-gene Bollgard cotton like 555. Beneficials make a bigdifferent even in varieties that have the worm technology.
Alabama cotton growers also saw more stink bugs this year, saysSmith, more since about 2005. And researchers are still learningabout the pest, he says.
But a few things seem real clear. First, a lot of growers arestill not tuned into stink bug damage, and theyre allowing toomuch damage as a whole before they treat. Stink bugs are difficultto scout for. Were refining it a little more every year. By thetime you find them in your field, as far as being visible, thedamage is somewhere between 10 and 20 percent of the susceptiblebolls that normally have internal injury, and that will causehardlock or rotten bolls when the cotton opens.
Another point that is often forgotten is that stink bugs have along life cycle  longer than any of the other cotton insect pests,says Smith. This life cycle can last up to 70 days.
If you have a stink bug on July 4, that same stink bug likely willstill be in the field when your cotton is maturing.
e-mail: phollis@farmpress.com