Cotton planting has progressed at a rapid pace for the last several days.  Many farmers in the Pee Dee Area are through planting (although some will be faced with replanting situations).   Forecasters are calling for increasingly warmer weather in our immediate future.  There is a chance for some shower activity today, but I'm hoping this one will miss the PDREC, so we can finally get a thrips test in the ground. 

     Hail has been a problem in a few areas.  Yesterday we looked at some cotton that had been decimated by an unusually  heavy hailstorm.  The highway was littered with vegetation from trees and plants growing along the roads.  There were pockmarks in the soil showing that the hail stones were about golf-ball size.  In some fields it was hard to find anything but stems. 

     The oldest cotton has no more that 3 to 4 leaves at this time.  Most of the crop will be at the one-leaf or cotyledon stage, or still under the ground, and a considerable amount of cotton seed has yet to be planted.  Most plants do not look particularly vigorous at this time.  Cotton growth has been relatively slow because of the cool daytime and evening temperatures.

Seedling Insect Pests
     Fortunately, there are not a great number of insects that we have to be concerned about at this time of year.  Thrips are the number one concern in most areas of the state.  A large percentage of the adult thrips that come to cotton will have originated in small grains.  Of course, wheat is the major host, with about 240,000 acres, followed by rye and oats.  Add them all up and there are probably close to 300,000 acres of small grains in South Carolina.  If we assume that the grain crops are grown in 7-inch rows, and there are 35 heads per row foot, then more than 2 million heads would be produced per acre. If only 1 thrips were produced per head the total number of thrips would exceed 600 trillion.  Add to this the trillions produced on wild host plants and you begin to see why most cotton seedlings will be visited by one or more adult thrips.  If the seedlings are not protected by an insecticide they will get munched upon.  Small grains are turning color now and are rapidly approaching maturity.   When there is nothing soft and juicy left for thrips to suck on, they will “abandon ship” and billions and billions will land in cotton fields.

     There are many different species of thrips, and several that may attack cotton in South Carolina.  Tobacco thrips, western flower thrips, and eastern flower thrips are probably the most common species in seedling cotton.  The large, black grain thrips you see in wheat is not a pest in cotton.  In fact if you see one in cotton it is probably just resting a bit before going out to search for another graminaceous host.

     If you are a gardener you have probably  noticed that thrips will feed on most of your garden plants.  Flower thrips may be found in the blooms of most species of plants, but certain species are preferred.  Both eastern and western flower thrips may be found on seedling cotton.  After cotton blooms, it is the western flower thrips that appears to dominate.  Tobacco thrips are rarely found on cotton plants later in the season.

     Cotton plants will eventually start growing at a more rapid rate than is presently the case.  Seedlings will simply outgrow thrips problems after about the first week in June.  By the time seedlings reach the 4-leaf growth stage, and growing conditions are good, we don't worry much more about thrips.  After cotton starts blooming thrips can once again build up large numbers.  Scouts sometimes find 100 or more western flower thrips in a  single bloom, but this is generally not an economic problem. 

     Thrips are quite tiny and the numbers of niches they can occupy are virtually limitless. 
Fortunately for cotton farmers, most other insect pests of cotton are not produced in such enormous numbers.

     Aphids were once considered important seedling pests.  In modern times these insects are noted more for their population buildup in July and August.  Their excreted honey dew coats the lower leaves of the host plants and the leaves in the upper parts of the plants become “droopy”.  Aphids have not bothered seedlings much since Temik came along, although an outbreak did occur in northeastern North Carolina last year.  What happens if aphids get resistant to Temik?  From what I hear aphids have developed some resistance to Temik, but since they are only exposed to aldicarb on seedlings, they get over it. 

     Spider mites may rarely be a pest on seedling cotton.  Such infestations are far more likely in the arid cotton states, such as Arizona and California. 

     With a trend toward more conservation tillage we might expect to see more cutworm problems in cotton.  Black cutworms and variegated cutworms are two species that are commonly found in cotton and in corn, especially in minimum-till situations.  Cutworms develop on winter annuals or other vegetation and will begin feeding on cotton when it pops out of the ground.  They may cut off the plants at ground level, cut terminals or cut off the true leaves.   When host plants are killed 3 to 4 weeks prior to planting cotton, the risk of having a cutworm problem will be greatly diminished.

Insect Situation
     There have been a few reports of thrips injury during the last few days, but that's about it.  Expect to see the numbers of thrips coming off of small grains to really be “kicked up a notch” during the next few days.  As temperatures go up, so will the thrips.  If necessary apply foliar sprays with Orthene, Bidrin or dimethoate.  Pull up 25 or more seedling plants and look for adult and immature thrips (a hand lens would help).  When you find one or more adult thrips per plant, and/or immatures on most plants then you may need to take action.  Do not let thrips infestations build up to the point that terminals become severely injured.  Plant maturity can be delayed and plants can even be killed.

Cotton Scouting School
     Don't forget, there will be Scouting Schools at Orangeburg on June 8 and at the Pee Dee REC on June 9.  Pesticide applicator certification credits and CCA credits will be awarded. 

IC-97
     You should have received this Extension Publication by now.  IC-97 contains the latest insect control recommendations.  Things change, so don't rely on old information.  Get rid of the older printing of IC-97.

Mitchell Roof
Extension Entomologist