Cotton Insect Newsletter Vol. 22, No. 2, May 26, 2004

Cotton Situation: Growers should have close to 90% of their planting done by now.  The South Carolina Agricultural Statistics Service indicated on May 1 that growers were expected to plant 260,000 acres.  The Ag Statistics Service also reported that a total of 314,750 running bales were ginned in South Carolina during the 2003 season.  That was 146 percent above 2002's ginning of 127,800 bales.  Planted acreage was down 24 percent from 2002 due to the extreme dry weather in the 2002 growing season.  Increased moisture persisted throughout the 2003 growing season producing much higher yields.  Overall yields were more than double the 2002 levels. Insect Situation: Thrips are out in force this week.  Most of the thrips I'm seeing are tobacco thrips, but I'm sure there are also some western flower thrips in the mix.   Westerns are more difficult to control, so if their numbers are down, insecticides may perform a little better than usual this year.   Speaking of thrips controls—I sprayed some plots here at the experiment station this morning.  The cotton was planted on May 10 and emerged to a good stand by May 18.  Thrips were beginning to hit the tiny seedlings by the time it was up to a uniform stand.  On May 26, there were close to 3 adult thrips per plant.  The two true leaves were puckered up and stunted considerably on most of the plants, and terminal buds were malformed.   This is a little later than I would want to spray if I were trying to make cotton; unfortunately, it's probably fairly typical of foliar treatments by farmers.   In my case I was trying to get thrips numbers to build up, so they could cause lots of damage, and produce plenty of babies.  If I were trying to get the most benefit from my foliar insecticide treatments, I would have sprayed on May 18, and then again about one week later. If you don't have scouts in the field checking  seedling cotton, farmers need to do some checking of  their own.  When you start seeing problems as you drive by a field, it may be too late.  It's always a good idea to monitor thrips populations in every field and look at damage to the plants.  When you see terminal damage on most plants, and one or more  adult thrips per plant (or the presence of immatures), then it may be necessary to apply a foliar spray.    By the time seedling plants have 5 true leaves, there is not much more to do.  Applications of foliar insecticides to older seedlings will not be profitable.  On tiny seedlings, a few thrips can do lots of damage by feeding in and destroying the terminal buds.  Foliar treatments applied at that time may prevent maturity delays in the range of 1-3 weeks.   If you wait until the damage shows up on older plants, you might get revenge with foliar sprays, but you won't get even.  Grasshoppers are the only other insect pest that has been reported to me as causing problems in cotton this week.   Eggs are laid in the soil and persist quite well within fields where growers have utilized minimum tillage operations.   Where hoppers are found in conventionally tilled fields, they have probably emerged from eggs laid in border areas, such as fence rows and ditch banks.  The pyrethroid insecticides may be used to control these insects.  Other labeled materials include Sevin, malathion and Lorsban.  When you kill a bunch of immature hoppers (the ones without wings) you may not be through.  It's not unusual for grasshopper eggs to start hatching in May and continue through June.  In other words, you could kill them all one week and your cotton could be infested the next week with another batch of hoppers.   How many hoppers does it take to cause problems?  I have seen thresholds ranging from 5-10 hoppers per square meter.   Plant stand is also an important consideration.   If the number of cotton plants has been reduced below a critical level, and you just can't stand it, then by all means spray.   When cotton gets to the stage where plants have 4-5 true leaves you are going to see an influx of beneficial insects and spiders.   Big-eyed bugs are one of the more common beneficial species (and incidentally, one of the best) to frequent cotton plants in South Carolina.  These true bugs have piercing-sucking mouthparts which they use to spear their enemies.   Their list of prey includes spider mites, thrips, aphids, eggs and immatures of bollworm/budworm, and tarnished plant bugs.   I always worry a little about these good bugs being confused with bad bugs, simply because they are often present in fairly high numbers.   Several years ago, I remember a farmer who sprayed his cotton for big-eyed bugs.   Cotton Scouting Schools: A Scouting School will be held, at the PDREC on June 8.  Registration will begin at 8:00 AM and the program will run from 9:00 to about 4:00.  There will be a fee of $10 to pay for educational materials.  Credits for CCA’s and private-pesticide applicator certification will be awarded for attendance at this meeting.    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 employer.  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