Cotton News Letter No. 3,  June 7, 2000

Cotton Situation: Cotton is growing well following some shower activity.  I know everybody didn't get rain, but there were some pretty substantial showers around.  It was just what the doctor ordered for cotton, but unfortunately, too late for much of the corn below the lakes.  It's too early to tell what the final acreage will be.  It seems that the forecast was for over 360,000 acres a couple of months ago.  Now we will be lucky to hit 300,000 as a result of the drought. After our Scouting School here at the PDREC yesterday, we looked at some April-planted cotton that had begun squaring. Most of the plants were squaring on the 7th or 8th node.  The majority of cotton fields have plants that are in the 1-6-leaf stage at the present time.  Insect Situation: There are still plenty of thrips around, but it looks like the hordes are beginning to dwindle down. Budworm activity has already begun, with eggs being laid in some pre-square stage cotton. Grasshoppers are still gnawing away on cotton leaves and a few armyworms may be found feeding on leaves.  Another leaf feeder, the Japanese beetle, may be found in some cotton fields. Beneficial insects and spiders are moving into cotton fields in a big way. It seems like I have been talking about thrips for too long.  Don't they ever go away?  Well, this week I think we are finally seeing a reduction in their activity.  Infested fields still have damaged plants and plenty of thrips feeding on leaves and terminals, but when plants get to the 5th and 6th leaf stage of development, it's usually too late for insecticide treatments to save the day.  I know some growers have already sprayed 2 or 3 times and are contemplating another treatment.  It's doubtful if you will gain anything by spraying, and we are fast approaching the time when an insecticide treatment could hurt you by wiping out beneficials, which could prevent economic damage from another insect pest.  We have always said that insecticides applied after the first week in June are risky. Back when the boll weevil was still a major pest on cotton, growers often applied a couple of pinhead-square applications with methyl parathion or Guthion. In fields where pinhead applications were applied, an infestation of budworms often showed up as a result of the beneficials being killed. It takes some time for populations of beneficials to build up again, and if moths lay their eggs while beneficial numbers are low, more worms will survive to attack the cotton plants. Grasshoppers are still a threat in some cotton fields.  Be alert to areas of cotton fields where the tops of plants are being cut out by grasshoppers, or where they are eating substantial amounts of leaf tissue.  Snowy tree crickets will also feed on leaves at this time of year.  Their numbers are usually not sufficient to produce economic damage.  Beet armyworms and yellowstriped armyworms are still being found in cotton, but their leaf feeding at this time of year should be relatively minor. We haven't seen a severe outbreak of beet armyworms for several years, hopefully, this won't be the year.  If you see a beetle feeding on leaves this week, there's a good chance it will be a Japanese beetle.  The immatures (white grubs) feed in the soil on the roots of grasses, where they pupate and the adults come out of the ground and make a real nuisance of themselves.  It seems like we have more and more of these critters every year.  They begin emerging about the middle of May and continue through June.  They seldom do enough damage in cotton to warrant spraying, but they can cause some headaches by feeding on corn tassels, rose bushes, crepe myrtles and other ornamental plants.  Japanese beetles are known to feed on about 275 kinds of plants, so if you don't see them in your cotton, there's a very good chance you will find them on plants around the house, or in some other crop. Is it too early for budworms or bollworms to show up in cotton? Absolutely not. We sometimes see leaf feeding budworms in pre-squaring cotton during the last week in May, in fairly large numbers. Of course this would have to be a conventional cotton variety, because Bt cotton would kill a budworm in short order, and probably do the same for a bollworms. This week up to 50 eggs per 100 plants were reported in the Lone Star area of Calhoun County.  Others have reported seeing fairly large numbers of eggs for this time of year. I don't expect much to come of this. Most of the infested fields will be in cotton varieties containing the Bollgard gene.  A conventional cotton variety could be damaged at this time if worms were to destroy the terminals in a large number of plants.  The delay in maturity could result in lost yield, and/or delayed harvesting.  In most fields with six or more true leaves, you should find a fairly high number of beneficials, usually featuring the big-eyed bug as the star performer.  For the most part, beneficials and Bt cotton should prevent economic losses from these early infestations of budworms or bollworms. Boll Weevil Containment: No boll weevils have been trapped to date in the Lexington County area, where 3 were captured in August last year.  Traps will start going up elsewhere on June 16.  It's regrettable when cotton fields have to be abandoned this time of year, because of poor stands, but it is getting a bit late for replanting. If you have to give up on a cotton field, the SC Grower Foundation is requesting that you destroy the plants. Cotton plants that are allowed to grow could provide a home for a weevil that might be thinking about coming to South Carolina to raise a family. If she were to deposit some eggs on these plants, and no traps were in place (because the trappers were told by FSA the field was destroyed), it could possibly be months before this reproductive site was discovered. Within a few months, boll weevils could have multiplied and spread to other areas of the state.    Mitchell Roof Extension Entomologist

This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. Brand names of pesticides are given as a convenience and are neither an endorsement nor guarantee of the product nor a suggestion that similar products are not effective. Use pesticides only according to the directions on the label. Follow all directions, precautions and restrictions that are listed. The Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, sex, religion, national origin, disability, political beliefs, sexual orientation, marital or family status and is an equal opportunity employee.  Clemson University Cooperating with U.S. Department of Agriculture and South Carolina Counties.  Issued in Furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of May 8 and June 30, 1914.  Public Service Activities