What is in this article?:
- Thrips off to big start in Virginia, North Carolina
- Foliar treatment needed
• Our region has earned the distinction of having the highest levels of thrips and greatest potential damage to seedling cotton of anywhere in the U.S.
• As if our high thrips populations weren’t enough, our often cool spring conditions can limit early plant growth, exposing the susceptible cotyledon to two or three true leaf stage seedlings to thrips for extended periods.
• Thrips damage at this growth stage can result in significant yield losses and maturity delays.
Foliar treatment needed
With the potential for thrips damage lasting up to 5 or 6 weeks after planting and seed treatments varying from about 2 to 3 weeks in their activity, a high percentage of foliar follow-up treatments for thrips is not surprising.
Although every year brings somewhat different, typically higher, rates of active ingredient to seed treatments, a look at the nicotinoids and their rates on seed suggest their performance against thrips should be similar. And that’s indeed the case.
Even back in the days when only Cruiser and Gaucho were available, many replicated tests suggested that these materials were essentially identical in their thrips activity — although many producers had their favorite.
Today, with insecticide plus nematicide plus extra fungicide on most seed treatments, recent tests in our area suggest that these combined seed treatments are similar in their activity against thrips, nematodes and diseases.
What’s new on the horizon?
• The Holy Grail of seed treatments would be a high rate (or new active ingredient) of an insecticide on cotton seed that would remain active for four to five weeks.
In many cases, our 3 weeks’ seed treatment activity seems to come up short by only a week or two.
So far, with the exception of a few testimonies to the contrary, this seemingly simple answer to short-lived seed treatment activity has defied the best efforts of major seed companies, consultants and university scientists.
Several high rate options will be evaluated here and elsewhere in 2012.
Another option will be the presence of multiple insecticides and nematicides on the same seed. One example for 2012 will be the Aeris/Poncho/VOTiVO option containing two nicotinoids and two nematicides, one conventional and biological. Whether these and other formulations will offer extended activity for thrips will be addressed in the coming year(s).
• In-furrow sprays with “new” materials showed some promise in North Carolina and Virginia in 2011. Although our data should be considered preliminary, Admire Pro (imidacloprid) showed extended activity against thrips in a test in Wilson County, North Carolina and in testing at the Tidewater Ag. Research and Extension Center in Virginia This and additional products will be evaluated more widely in 2012.
• Although approved for a federal label in December 2011 the introduction of the aldicarb-based, Temik-like product Meymik will likely face further obstacles before being available to cotton producers, possibly by 2013.
Probably produced, formulated and shipped from China, little is known about the possible costs, flowability and efficacy of Meymik.
Additionally, the successful re-registration of aldicarb (a carbamate), the active ingredient, by the EPA in 2014 or 2015 is not a given.
• Foliar insecticides following seed treatments remain an important component of our thrips arsenical.
As part of a Southeast Cotton Working Group initiative, Cotton Incorporated has sponsored a series of tests which evaluated new and standard foliar insecticides for thrips control in Virginia, North Carolina, South Carolina, Georgia and Alabama.
Two insecticides, Radiant and Benevia, showed thrips control on a par with acephate (Orthene and other brand names).
We and others have confirmed that the combination of Orthene following a seed treatment greatly increases the odds of having to treat later for cotton aphids and spider mites.
Radiant and Benevia will likely be significantly less disruptive against beneficial insects.
The major downside of these materials is their prohibitive $20-$30 per acre cost at the rates tested.
This year’s series of tests in our region will evaluate the effectiveness of several rates of these insecticides in the hope that one or both may give us an additional tool in minimizing our annual thrips dilemma.
In essentially all of our research trials, when the cotton plants have an average of approximately 5 true leaves with adequate moisture levels and reasonably warm weather, thrips control was no longer needed.
Our best outcome for a reasonable “thrips season” would be warm moist conditions conducive to rapid seedling growoff — and perhaps a few more mid-May cotton planting dates.
(You’ll also want to read Upper Southeast cotton growers brace for thrips invasion and Growers in 'thrips central' ready for 2012 battle).