Most cotton producers probably would not think of the Carolinas and Virginia as routinely leading the rest of the Cotton Belt in thrips levels and damage. But whether a cotton region qualifies for this dubious distinction based on thrips levels or based on yield losses in untreated cotton, this area wins hands down.
In North Carolina and Virginia, the often cool, and sometimes wet seedling grow off conditions, coupled with the very large ratio of thrips host acreage to our relatively small cotton field size (the average is 14 acres) and short production season, often seems to create a “perfect storm” of thrips headaches.
Early, aggressive control of this troublesome pest complex is often an important component of profitable cotton production here. An early, vigorous cotton crop can help set the stage for late-season insect management opportunities (such as lesser pressure from bollworms and stink bugs), for more effective defoliation, and for earlier harvest.
For most producers, a foliar application following the use of a seed treatment such as Gaucho Grande or Cruiser, should be considered almost automatic in cotton with conventional row spacing (30 to 40 inches). In all but rare cases, the approximately three weeks’ protection provided by seed treatments is not sufficient to avoid significant thrips damage in this area.
Research suggests that the optimal timing for this foliar spray should coincide with the appearance of the first true leaves.
In Roundup Ready or in Liberty Link cotton, this application can be very inexpensive if piggybacked with Roundup (or other glyphosates) or Ignite. In most cases, this single application at the first true leaf stage provides cotton seedlings enough thrips protection time to get the plants “over the hump” enough to avoid further thrips vulnerability and at the same time into a period of fewer migrating thrips.
With Temik 15G at 5 pounds per acre, the 4 to 6 weeks thrips activity (under good product uptake conditions) often provides “season long” thrips control. Unlike with the seed treatments with their associated foliar spray, scouting becomes more important with this product. Possible treatment following Temik should be based on the finding of crinkled (or possum-eared) newly forming young leaves and deformed or darkened buds along with the presence of immature thrips
Listed below are several at-planting insecticide options for thrips control in conventional row cotton:
(1.) Temik 15G — Temik 15G at the 5 pound product rate generally provides good thrips control and suppression of early season cotton aphids, and is still generally considered the standard treatment in North Carolina. Under sufficiently dry conditions, however, uptake of the active ingredient, aldicarb, can be reduced to the point that a foliar treatment may be needed.
Although not always significant, Temik often provides earlier grow-off and fruit set, greater persistence, earlier maturity and higher yields than seed treatments alone. The three pound product rate may be adequate for cotton planted after about May 15 to 20.
(2.) Gaucho Grande and Cruiser Seed Treatments — These worker-safe, easy to use, thrips control options have more often than not looked impressive in all parameters evaluated in university tests except one — persistence. Plan on approximately three weeks’ thrips protection with either of these products. Therefore, plan on using a foliar application for supplemental thrips control.
These seed treatments, coupled with an early foliar treatment such as Orthene, have performed well, and are very reasonable when the foliar product is piggybacked with an early Roundup (or other glyphosates)l or Ignite application.
These products would also likely be an acceptable choice for cotton planted after about May 15 to May 20, perhaps avoiding a supplemental foliar treatment. Seed treatments and Temik generally result in low early aphid levels.
(3.) Foliar Treatments — Except in ultra-narrow-row cotton, automatic applications for thrips (instead of an at-planting insecticide) are generally to be avoided in conventional row cotton. Although inexpensive when applied in a band with herbicides, these products provide limited residual control and, can contribute to secondary outbreaks of budworm (on conventional cotton) and budworms.
However, well-timed, need-based foliar treatment(s) following seed treatments or granular at-planting insecticides can have a significant positive impact on early plant growth, maturity and yields.
Do not overlook the possibility of a very early scouting-based treatment at the expanded cotyledon stage when the first true leaf is just visible.
(4.) Do Nothing — As evidenced by the high damage, retarded maturity, and low yields in most check plots over the years, and by grower and consultant observations of unthrifty plants and poor stands in rows in which the ‘Temik tube” was clogged, the absence of both an at planting insecticide and a foliar application is asking for trouble. Fortunately, this kind of a thrips feeding frenzy adventure is rare.
All Clear — In essentially all of our research trials, when the cotton plants have an average of approximately 5-6 true leaves with adequate moisture levels, thrips control should no longer be necessary if adequate moisture and reasonably warm weather exists.