Cotton Insect Newsletter Vol. 22, No. 4, June 9, 2004

Cotton Situation: Planting is near completion.  Cotton is growing well where there has been adequate rainfall.  We are seeing lots of scattered thunderstorm activity this week; unfortunately, those areas that have been getting some rain seem to get more, while those that are dry can't seem to attract the right kind of clouds.  Consequently, there are still some areas of the state that are extremely dry. Insect Situation: Cotton has simply outgrown the thrips in many fields.  I doubt that there will be many reasons to spray for thrips this week.  I have cotton that was planted on May 7 that has seven nodes and is just beginning to square.  Another field was planted next door on May 10 to test insecticides for thrips control, but thrips have really stunted this cotton.  It is nowhere near putting on squares.  In plots, where no insecticides were applied, it is still hard to find actively growing plant tissue.  This cotton could probably still profit from an insecticide application.  Also, the plants are supposed to have 5 leaves now, so technically it's too late for Roundup.  Goose-grass, sickle-pod and pigweed plants are proliferating and it's going to be a long, long time until these plants are able to offer any serious competition to the weeds.  It looks like an old-fashioned hoe may be the answer.  When you start cotton plants with 6 or more leaves, you should be seeing some of the following insects.   It's not unusual to see eggs, and/or small bollworms and budworms on squaring and pre-squaring plants.  You will probably be seeing some yellow-striped armyworms.  These worms will feed on leaves, but economic problems are extremely rare.  You might even see some beet armyworms.  Every so often, we get some beets showing up in cotton as early as May.   Worms chowing down at this time of year will usually have a tough time getting established because of the beneficial arthropods and Bt cotton (which may upset their little tummies).  Japanese beetles have been observed feeding on leaves.  These insects will infest widely scattered areas of a field, where they may congregate on a few plants.  There should not be any economic problems, however. Cotton fleahoppers may be found in cotton fields now.  We saw several on Tuesday at the PDREC Cotton Scouting School.  These bugs have the potential to damage terminal buds and pinhead squares.  The adults are pale green in color with small black specks on the upper surface of the body, which is about 1/8” in length.  I have not seen any tarnished plant bugs (lygus bugs) as of yet, but I would expect that they are moving in to older cotton fields.  They will feed on small squares and cause them to abort.  There should be a few aphids on seedling plants—usually on the undersides of the leaves.  In the old days, early infestations of aphids were fairly common.  I have not seen an economic infestation of aphids on seedling cotton in 22 years, but I wouldn't put it past them.  Phil Roberts reported last week that spider mites were building up on cotton in some areas of Georgia that had been extremely dry.   Populations of mites have been high on melons and cucumbers in that state. At the Scouting School, we also observed lots of big-eyed bugs, damsel bugs, and some other predators.  I'm sure that you will find fire ants in most fields as well.  Most of us don't think about these little varmints as being beneficial, but they will eat eggs and immatures of bollworm and other insect pests. There are literally hundreds of species of insects that may be found in cotton fields.  The great majority of these have no effect on the plants.  Many species are beneficial in one way or another.  There are less than 20 species that really have the potential to cause economic damage.  Cotton Scouting:  Attendance at the Scouting School was at an all-time low yesterday.  We only had about 25 people attend.  In the 1980’s, when cotton acreage was smaller, we could expect 75 or more to attend this school.  I hope this doesn't mean the farmers are cutting back on costs by not hiring consultants and scouts.  Bt cotton is still vulnerable to insect pests such as stink bug, that make scouting just as important as ever.  Even BG II will need to be scouted.  That may have been my last Cotton Scouting School on June 8, but it should not be the end of cotton scouting and consulting.   These activities should go hand in glove with any cotton production system.   Insects, weeds and diseases are not going to go away.   It's very unlikely that cotton pests will ever be completely overcome by genetically manipulating the plant.   Chemical intervention will still be needed on a timely basis.   A good cotton scout provides the information that makes it possible to properly time applications of pesticides—to get the most bang for the buck.    Mitchell Roof  Extension Entomologist

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