Cotton Insect Newsletter Vol. 19, No. 3, May 30, 2001

Cotton Situation:  It was good to see some water falling from the sky.  Most of us hadn't seen an inch of rain in several months, but I heard that was about the average amount that fell across the state Tuesday morning, with some areas getting 2-3 inches. Cotton farmers should have over 90% of their planting done and the remainder should get planted this week, other than a small amount that will be planted behind wheat.  I estimate the average growth stage for the cotton plants that have emerged throughout the state at “3-4 leaf.”  There are plenty of fields where cotton seedlings have just emerged or are barely in the cotyledon stage, and there are a few early-planted fields in which a scout might find a square this week. Insect Situation:  The major insect pests in cotton fields this week are still thrips.  It is quite possible that the rains will boost the uptake of Temik where soils have been extremely dry.  This could provide sufficient control of thrips that have just begun to establish damaging infestations.  Don't expect much help where there has already been a considerable amount of economic damage to leaves and terminal buds.  When most of the new leaves have been badly crinkled and scarred and terminals are badly damaged, it will be necessary to apply a foliar insecticide treatment to kill the thrips that are already there.  Otherwise, it will be a long, hard struggle for the damaged seedling to resume normal development. We usually try to do some thrips-control tests each year to monitor the efficacies of new and recommended insecticides.  Generally, our thrips control tests are planted early in May, so that plants will be up to a good stand when the thrips start arriving around the middle of May.  Any cotton planted from now on should be relatively free of problems, although I remember a couple of years where thrips continued to infest cotton seedlings until about the middle of June.  This year, I will have a late-planted test (one will be planted this week) to monitor thrips infestations and attempt to determine if there is any advantage to applying seed treatments, soil insecticides or foliar treatments at this late date. Our economic threshold for thrips has always been one adult per plant through the 4-leaf growth stage.  In the real world, the adult threshold is best employed from the time plants emerge to a stand until they reach the 2-leaf growth stage--the earlier the better.  Pull the seedlings from the soil and shake them inside a container or on to a handkerchief to dislodge the thrips.  Or, you can just pull up the plants and examine the undersides of leaves or cotyledons and terminal buds.  Look closely at terminals--if adults are present you will usually find them wedged within the folds of the first or second true leaves.  When you find one adult thrips per plant on cotton with 2 or more leaves, you will usually find a lot more nymphs.  The presence of immature thrips on most plants tells you that your insecticide has not provided sufficient control for several days. There are still reports of small grasshoppers feeding on cotton seedlings.  When seedling cotton plants are the only green things growing in fields where the grasshopper nymphs are emerging, there is not much doubt where they are going to find their food. Cutworms are a potential threat in fields with minimum tillage.   Damage by cutworms may also be confused with grasshopper damage.  You usually have to dig up a little soil around the bases of cotton plants to uncover cutworms in the heat of the day.  Also, keep an eye out for false chinch bugs.  We don't really expect them to do much damage, but there is always a chance they could present problems for very small seedlings.  Reports of false chinch bugs in cotton have increased each of the last two years.  Cotton Scouting Schools:  I can't believe it's time to have Cotton Scouting Schools again.  Seems like they come around earlier every year.  Maybe it has something to do with my advancing age, but days just don't seem to last as long as they used to.  The first Cotton Scouting School will be held at Orangeburg-Calhoun Technical College on June 5, and the next day, June 6, we will do the same thing at the PDREC in Florence.  Details about these meetings were presented in the first newsletter.  If you have any questions about the meetings and need to talk to someone, just give your County Agent a call.  Learn how to identify insects, weeds and diseases; learn how to scout a cotton field; learn more about the growth and development of the cotton plant, and learn how much there is to learn.  Cotton Listserver:  For those of you that are signed up to receive email via the Cotton Listserver, I'm sure you are aware that a virus (specifically the Hahaha virus) recently showed up on some computers.  There is really no way for us to track down the originator.  If the proper anti-virus software was installed on your machine this virus was probably quickly confined and removed.  I regret that the Cotton Listserver was associated with a virus, but we will try to shore up our defenses as much as we can and continue to use it.  But remember this: don't open email messages from unidentified sources, just delete them, and make sure that you have up-to-date anti-virus software installed on your computer.   Mitchell Roof  Extension Entomologist

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