Cotton Insect Newsletter Vol. 21, No. 6, June 25, 2003 Call 1-877-629-1474 for Cotton Insect Hotline

Cotton Situation:  Most cotton lands are beginning to dry out some this week.  Temperatures have been mainly in the 90's.  By the end of this week, cotton plants will have begun to square in about 50% of fields.  Scouts should begin to monitor retention rates soon after squaring begins.  Pinhead squares will appear in the axils (point of attachment of leaf to main stem) of nodes 4-6 in early-maturing varieties and nodes 7-9 in later-maturing varieties.  Plants that have not begun to square by node 9 may be in trouble.  Excess moisture or poor fertility could be to blame.  Begin checking for pinhead squares when cotton plants have eight or more true leaves.  Square retention rates for the first five fruiting nodes should be 80% or better to attain optimum production.  Pinhead squares will occur by about the 8-leaf stage in early maturing varieties.   Remember when counting nodes on the main stem, disregard the cotyledons.  Count only nodes that have true leaves attached. How many plants do you check to determine square retention rates?  I suppose an absolute minimum would be 25 -- five plants in 5 different locations.  But 50 plants would be better, and in a large field 100 would be ideal.  Insect Situation:  Scouts reported the first cotton fleahoppers here at the PDREC on Monday.  These insects will attack pinhead squares and terminals.  Tarnished plant bugs have not been reported yet at this location, but I suspect they will be moving off of wild host plants into cotton that has begun to square.  Both of these insects have been convicted of producing “crazy cotton.”  I have never considered either of these insects to be a major problem in South Carolina.  But cotton is off to a slow start, and it really doesn't need any further delays in maturity.   Therefore, let us be a little more cognizant of the potential for problems that exist when plant bugs build up in pre-blooming cotton. Cotton fleahopper are pale green in color and adults are about an 1/8 of an inch long.  They are flat bodied insects with piercing sucking mouthparts.  These bugs hibernate as eggs on croton, cut-leaf evening primrose, and other wild hosts.  Ironically, the immature fleahoppers have been observed feeding on bollworm eggs.  Immatures are also pale green with prominent reddish colored eyes.  The tarnished plant bug adult has a brown-colored body, mottled with small irregular white patches.  They are two or three time bigger than adult cotton fleahoppers.  Along each side of the body on the rear end of the wing, there is a clear, black-tipped triangle.   The light-green nymph has five black dots on its back, long antennae, and no wings.  Both fleahoppers and lygus bugs are referred to as plant bugs.  They feed by inserting their long needle-like mouthparts into tender plant terminals, squares and other tissues and sucking up the juicy morsels.  Injured squares will turn brown and drop off.  Terminal feeding may result in the loss of apical dominance and subsequent multiple branching.  All this damage takes time for the plant to fix.  In other words, maturity is delayed.  Later in the year, tarnished plant bugs will attack larger squares.  The evidence of this feeding will be shown when the buds turn to blooms and reveal the black anthers and puckered petals.  They will also do some damage similar to stink bugs when they pierce small bolls and penetrate the seeds. Budworms appear to be the prominent heliothine species this week, at least in cotton and tobacco.  In a Hel ID egg test, Candy Roach found 72% tobacco budworm from a cotton field in Darlington County on June 24.  Eggs collected from a Marlboro County field on June 23 were 95% budworm and 5% bollworm.  This is the proportion that I would expect to see at this particular time.  Most self-respecting corn earworm (bollworm) moths have been attracted to the luscious corn crop to deposit their eggs. My scouts found some beet armyworm egg masses in Darlington County.  Uncharacteristically, these had been deposited on the tops of the leaves.  Later in the season, you would expect to find them on the undersides of leaves.  Slugs?  Yes, there was a report concerning slugs sliming up some cotton in Marlboro County.  These were strip-tilled fields near a swamp that had been plenty wet for an extended period of time.  They did not appear to be doing much damage to cotton with 9 to 10 leaves.  I'm sure that this hot, sunny weather will provide the cure. Boll Weevil Traps:  I have heard a couple of complaints about traps not showing up yet.  Remember that the deadline for trap installation is July 9, so they may not have got around to your farm.  However, if you notice a situation where a field is not trapped, but everything else around it is, then you should be concerned enough to call 800-269-9928.   Mitchell Roof  Extension Entomologist

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