Cotton Insect Newsletter Vol. 19, No. 11, July 25, 2001 Call 1-877-629-1474 for Cotton Insect Hotline

Cotton Situation:  Rain, rain, rain - - we need the rain, but we also need to get into the fields to spray for bollworms.  Cotton plants were beginning to go down hill fast after two or three weeks without any significant rainfall.  It's very common now to see blooms in the tops of cotton plants that were planted in April and the first week in May.  The South Carolina Weekly Weather and Crop Bulletin pegged the condition of this crop as 4% poor, 26% fair, 60% good and 10% excellent for the week ending July 22.  Scouts are sure to observe lots of small squares and small bolls that have fallen off of the plants following the rain.  Don't confuse this physiological shed with insect injury.  Pick up some of the fallen forms from the ground and check them out.  You should find that most of the fallen forms are free of insect injury.  Squares damaged by bollworms will have flared bracts.  Insect Situation:  We have caught a lot more bollworm moths in pheromone traps this week.  Egg counts have increased in the Savannah Valley and the Pee Dee area.  There will probably be some increased egg laying in the Piedmont by the end of the week.  Most of the activity has been from bollworm, as would be expected this time of year; however, in Marion County area, Mitch Binnarr and Wes Martin checked the eggs in two fields on July 23 and found that budworms comprised 60 and 70% of the totals examined. There are a few fields at the PDREC that have been getting quite a bit of attention from bollworm moths and there are some fields, primarily those planted in April, that are being ignored.  We just finished spraying a bollworm control test for the first time where we had finally picked up a few economic numbers of worms on Monday.  I would have liked to have sprayed it Monday, but the rains came.  There will probably be lots of farmers in the same situation this week - - needing to spray, but unable to get in the field.  I'm afraid that bollworms given a couple of days head start will be tough to control.  When you do get a shot at them, use medium to medium high rates, and come back within 5 days with another treatment.  Aphids may not be totally out of the picture, but numbers have dropped dramatically in most fields.  Cotton planted in late May and June seem to have most of the active infestations of aphids this week.  The fungus appears to have knocked out most of the infestations in older fields of cotton from the North Carolina border to the Savannah River. Stink bugs have been active in some fields, however, I have checked a lot of fields here at the research station and across the Pee Dee area, where it took a lot of looking to even find a damaged boll.  Most of the stink bugs that I have seen have been green stink bugs, although I have heard others say they are seeing more brown stink bugs.  Keep in mind that lygus bugs and some other species of bugs will cause some of the same injury symptoms to small bolls.  When these bugs penetrate a boll, they will also produce warty growths on the inner surface of the boll wall. Don't assume that you are going to have stink bug problems just because you haven't sprayed.  Such assumptions can be expensive.  For if you assume that a field has stink bugs, you will probably spray it with a pyrethroid or an organophosphate (methyl parathion or Bidrin).   Once you have made that first assumption and sprayed, you will probably want to do it several more times.  Since stink bug problems can start with small boll development, you will probably have to protect a field for at least 6 weeks - - if you assume that you have a problem.  Let's see, if you sprayed once a week, the assumptions would have cost you more than $40 per acre.  If you had a scout check for damage (quarter-sized bolls) once a week, and then only sprayed that one time when the scout reported 25% damage, it would have cost less than $10 per acre.  Also, the beneficials that were conserved during the 5 weeks that you weren't spraying could have been available to help out with those pesky armyworms and aphids. Leaf rollers have been very active in an area south of Bishopville.  There were quite a number of fields with cotton plants that had barely started, or not even started squaring last Friday.  You could easily find damage to leaves and less frequently to terminals.  Leaf rollers produce copious amounts of webbing which they may use to construct nests on the undersides of leaves, or they may build nests by rolling a single leaf, or by rolling multiple leaves together.  The leaf feeding may initially be confused with an insect such as the beet armyworm, however this species is not gregarious, but seems to be perfectly happy to subsist alone.  This leaf roller is a striped, greenish-colored worm with several black spots on the back.  It is unlikely that this insect will do any economic damage to cotton.  Even in the heaviest infestations that I observed, there were less than 5% of the plants showing any damage symptoms.  Boll Weevil Containment:  Randal Lynch told me this morning that there had been several instances of traps being vandalized in Marlboro County.  If you see anyone vandalizing traps, please report it immediately by calling the toll-free number 800-269-9928.  There are also some cotton fields out there that have not been trapped.  This is the time of year when boll weevils are moving about and   they just might decide to take a ride on a module builder from Yazoo City, MS to Orangeburg, SC.  Remember what happened back in 1995.  The next thing you know, we will have boll weevils all over the place.  If you see fields not being trapped, report it by calling the number above.   Mitchell Roof  Extension Entomologist

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