Cotton Insect Newsletter Vol. 20, No. 5, June 19, 2002 Call 1-877-629-1474 for Cotton Insect Hotline

Cotton Situation: I have been looking at the “South Carolina Crop and Weather Report” for a similar time frame in 2001, which was a pretty dry year.  Moisture was generally adequate and the crop was mostly in good-to-excellent condition.  This year, moisture has become a limiting factor somewhat earlier.  Moisture conditions throughout the state were judged as 36% very short, 47% short, and 17% adequate in the report for the week of June 16, 2002. Where moisture has been short, cotton plants appear to still be standing up fairly well, and from the road they look good.  When you get out in the field, you will notice that the plants are about 2/3 (or less) the size that they should be.  Inter-nodes are shortened, and leaves are fairly small.  Reductions in vegetative growth will also result in diminished fruit production.  Well, that's the bad news. Hopefully, the forthcoming rains will get most cotton plants back on track for good growth and development.   Scouts should be aware of the tendency for squares to shed when plants are under moisture stress.  Don't confuse square loss from moisture stress with that caused by insects.  When you see a high percentage of squares being shed, and you aren't finding any plant bugs or other insects that might be damaging squares, then moisture stress may be the causal agent. Hotline: I mentioned last week that the Cotton Insect Hotline is being updated on Tuesday and Friday mornings between 8:00 and 10:00 AM.  Information may also be obtained via email on your personal computer from “Cotton Insect Blurbs,” which is published on Clemson University's Cotton Listserver.   Blurbs are sent when I need to get information out in a hurry about an insect problem, or maybe I just have a bit of information that I was unable to include in the “Cotton Insect Newsletter.”  If you want to get on the Cotton Listserver, just send your name and email address to me at my email address mroof@clemson.edu.  Also, notice that the header at the top of the page includes my telephone number, my email address, my real address, and the number to call for the Hotline.   Insect Situation: We are seeing more activity from both budworm and bollworm this week.   Moth captures in pheromone traps appear to be down slightly from last week, but we are finding eggs in most fields where plants have begun to set squares.  Egg numbers are moderate to high for this time of year.   Counts in our plots at the PDREC have ranged from about 25 to 60 per 100 plants.  We have seen counts of small worms from 2 to 6 per 100 plants on Tuesday morning.  These counts were below the treatment threshold of 15 small worms for conventional cotton in the PREBLOOM stage of growth.  Square damage ranged from 0.5% up to 8%.  The treatment threshold for square damage is 20%.  We do not have an egg threshold for PREBLOOM cotton.  An insecticide treatment should not be needed in Bt cotton prior to bloom, so the 2002 cotton insect control recommendations (IC-97, Cotton Insect Management) does not include a treatment recommendation. Beet armyworms are still showing up in cotton fields throughout the state.   Most of the time “their bark is worse than their bite.”  You are going to see a few widely scattered plants that are almost totally destroyed, and a lot more that have some leaf feeding.  I had a report from Steve Roach that he saw a field that had 18 egg masses per 100 plants.  That sounds like a pretty heavy infestation since if that many egg masses were visible, you can bet there were more than that many which were unseen.  There can be anywhere from 50 up to 100 or more eggs per mass.    One word of caution -- I would not use the threshold that is recommended for controlling beets in late July and August.  There is currently a full load of beneficials in cotton fields, since most have not been sprayed and predators and parasites will hold beets in check in many fields.  I would not treat a field unless the majority of plants were showing leaf damage and there were worms present on most of the damaged plants.   If you went by the same threshold that is recommended in blooming cotton of 5 hits per 100 plants, many fields would be sprayed needlessly. Tracer, Steward or Intrepid would be some of the best materials for control if you really need to spray a field.  Coverage of these small plants should not be a problem as it typically is later in the season with beet armyworm control.  Mitch Binnarr tells me that there have been some good results with 1.5 oz Tracer.  I have seen 1.6 oz work well on a little bigger cotton plants.  Intrepid is recommended at rates of 4 to 10 oz per acre, and I would suspect that the lower rate would do the job.  I don't have any information on lower rates of Steward, but the lowest recommended rate on the label is 9.2 oz per acre. False chinch bugs are present in many cotton fields in fairly large numbers.  They should not be doing any damage to the plants, but they just seem to be hanging out there.  The same can be said for the brown cigar-shaped click beetles that congregate in cotton.  You can find them on almost every plant in some fields.  Sometimes there are two or three per plant, but they don't feed or reproduce there.  They might grab an occasional drink from a nectary, although I have never seen one of them do so.   That reminds me of what Emmett O. Dameron used to tell when we were in the Army, “You know, Mitchell, everybody has got to be somewhere.”  And I guess the same can be said for those brown cigar-shaped click beetles.   Mitchell Roof  Extension Entomologist

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