The 2015 crop is generally off to a very good start. So far, we have had excellent planting weather for most parts of the cotton belt. Warm temperatures have resulted in vigorous growth and rainfall has been timely for the most part. There are of course a few exceptions where growers experienced dry conditions in some areas and heavy packing rains in others, however, most of the emerged cotton I’ve seen to date looks very good.
For early May planted cotton, thrips control of seed treatments is likely beginning to diminish, therefore growers need to be actively scouting for thrips damage to determine if foliar sprays are justified. Please see a previous article from Dr. Reisig concerning thrips control options and the timeliness of foliar sprays (just click here or visit http://cotton.ces.ncsu.edu/2015/05/should-you-spray-for-cotton-thrips/). We have yet to experience our major thrips flight from weedy hosts into cotton. There will be several fields that do not need any foliar sprays, as growth has been quite vigorous and at-planting control measures have sufficed. However, this can only be determined through frequent and thorough scouting. Remember that cotton is most sensitive to thrips damage at the 1st true leaf stage, which is illustrated in the photos below. Although foliar sprays at later stages may occasionally benefit yields, targeting sprays at the 1st true leaf has been proven to be the most effective.
Growers should also pay attention to any herbicide injury that may have occurred. Herbicide injury, as illustrated in the photos below, slows down seedling growth, allowing thrips to feed longer on developing leaves. In many cases, at-planting control measures may expire before seedlings “come out” of any transient herbicide injury and reach the 4-5-leaf “safe stage” from thrips. A well-timed foliar spray, when scouting has suggested that thrips are present, can alleviate most issues related to herbicide injury.
Courtesy Collins, Reisig, Edmisten, & York, NC Cooperative Extension