Thrips control plan needs to be in place for 2013 cotton crop
• Managing thrips is always a challenge in the northern half of North Carolina and in southeastern Virginia — an area often referred to as ‘thrips central’.• What system growers use to manage thrips early in the growing season in 2013 is not so important.• What is important is that they have a plan and that they manage these insects.Otherwise, they can expect yield loss and in some cases quality loss, too.
December 21, 2012
In terms of yield and quality, the 2012 cotton crop in the Upper Southeast will likely end up among the top two or three of the past decade.
In terms of what this past year’s crop could have been, it clearly had the potential to be one of the top crops in recent memory.
Though growers didn’t know it at the time, early season damage from thrips was likely one of the culprits, along with Mother Nature that held this year’s cotton crop back.
In years, like 2012, with high thrips populations and extended cool weather after planting, growers understand just how much they miss having an old standby, Temik, to manage thrips and nematodes.
Entomologists, including Jack Bacheler and Dominic Reisig at North Carolina State have initiated a number of innovative research projects to offset the continued absence of aldicarb from the marketplace.
“What we really need is a treatment that will work well enough on thrips that growers don’t have to come back later in the season with a foliar application. For example, we often need Orthene to supplement seed treatments, and these can be disruptive and can lead to more spider mite problems,” Bacheler says.
Virginia Tech Entomologist and State IPM Leader Ames Herbert has one of the most extensive thirps management research programs in the country. He says growers want a magical, silver bullet treatment to replace Temik and Temik plus acephate, but that elusive remedy just isn’t available.
Herbert, who works at the Tidewater Agriculture Research Center in Suffolk, Virginia, says despite the absence of a magical, one-shot cure for thrips, there are plenty of options that growers can use to effectively manage these tiny insects.
Speaking at a recent North Carolina cotton field day, North Carolina State University Entomologist Bacheler confirmed some bad news that most growers knew was coming.
Temik replacement doubtful
It doesn’t look like the much-promised Temik replacement and aldicarb product Meymik will make it into the market place in time for use in 2013.
Whether or not Meymik, or any meaningful aldicarb product will ever make it to the market is far from certain.
The company, More Economic Yield, or MEY Corporation, isn’t talking about the future of Meymik, other than to say construction of a production facility in Georgia has been delayed.
Causes for the delay vary from source to source, but the bottom line is no Temik-like product for 2013.
Without Temik more and more growers are depending on seed treatments to manage thrips. The most popular of these treatments contain imidacloprid, deemed by some to be the most widely used insecticide in the world.
Imidacloprid is a neonicotinoid, which acts on the central nervous system of insects. Technically, it blocks the nicotinergic neuronal pathway, which less technically kills the insect.
Because it binds much more readily to insects than mammal neuron receptors, imidacloprids are relatively safe for humans to use — another big plus to being the most often used insecticide in the world.
This family of insecticides has been around a long time and many generic products containing imidacloprid are available and used as seed treatments for thrips. These insecticides do work, but they just won’t hold up season long under heavy thrips pressure, Bacheler says.
Danny Pierce is a long-time North Carolina Crop Consultant, with more than 30 years in the business. He may just be the dean of licensed crop consultants in the state. He says, he has long questioned the rates of imidacloprids used in seed treatments.
Two years ago Pierce began doing some private testing on higher rates of imidacloprid and made his own seed treatments, with some outstanding results.
Since this treatment is off label, Pierce took his findings to Bacheler, who included them as part of his thrips management research program.
Bacheler looked at Pierce’s results and began testing high rates of the material used as a seed treatment.
“At first look, it didn’t look all that great,” he says. “But after we picked the cotton and processed the data, a 6X treatment of imidacloprid did well. In other tests a 10X rate looked good on cotton, even in areas with fairly high thrips populations,” Bacheler adds.
Working with North Carolina State Ag Extension Agent Norm Harrell in Wilson County, N.C., Bacheler says they came up with some interesting results that may help growers with thrips management next year.
Check plots beat up
“In the test, the check plots were pretty well beat up, which is what you would expect in areas that traditionally have high thrips populations. The next treatment was Avicta, and four weeks after application, the cotton plants were beginning to look pretty beat up as well, again what is expected with high thrips pressure,” Bacheler says.
However, when they added imidacloprid to the Avicta seed treatment, the plants looked significantly better, the North Carolina State entomologist says.
“We had similar, though less conclusive, results at the Upper Coastal Plain Research Station in Rocky Mount, N.C. when we applied the same combination of seed treatment and imidacloprid.
“So, this does give us some optimism that treatments like this can improve the tools we do have to manage thrips and make some of these more commonly used seed treatments work better and/or longer,” he adds.
The farmer field results in Wilson, N.C., points out another important part of any overall thrips management strategy — the grower. Bacheler says the grower did an outstanding job of applying the material right down the seed row.
In Rocky Mount the application didn’t go on quite so efficiently and the results weren’t quite as good, he says.
In the Wilson test, Bacheler points out by applying more imidacloprid to the seed treatment proved to be efficient, reducing the number of thrips per five plants from 250 in the check field to 9.5 for the test treatment. While that level of control might not be ideal for some growers, it is clearly a big improvement over seed treatments alone for thrips management.
Bacheler says he hopes the results of these tests will inspire companies that sell imadicloprid seed treatments to re-evaluate their labels and, hopefully, increase the label rates to help growers improve the length of control of thrips offered by these products.
Managing thrips is always a challenge in the northern half of North Carolina and in southeastern Virginia — an area often referred to as ‘thrips central’.
This area had a significant reduction in cotton acreage last year and most experts contend the reduction will be even more severe in 2013.
Fewer cotton acres, combined with the need for increased yield and quality to make a profit growing cotton, will likely force growers to plant cotton on their most productive land.
The same combination will make it even more imperative to keep young cotton plants healthy and growing during the highly variable weather conditions that traditionally occur in the area during the first couple of months of cotton production.
Will probably need foliar treatment
“Whether I like it or not, what this probably means is that for early-planted cotton in most of North Carolina and Virginia, we are going to have to use a foliar insecticide to supplement seed treatments,” Bacheler says.
“The good news is that these foliar materials, primarily acephate (Orthene) have performed well in our tests and in tests with Ames Herbert in Southeast Virginia,” he adds.
For growers, paying the $20-$25 dollar per acre cost of an additional foliar insecticide will likely become a trade-off on yield and quality of their cotton crop.
It will be a chore for cotton growers, but Bacheler says using a hooded sprayer is one way to improve efficacy and reduce costs of using a foliar-applied insecticide to augment seed treatment control for thrips.
The over-riding bad news for cotton growers in 2013 is likely going to be low prices.
For cotton growers in the Upper Southeast, the secondary bad news is no Temik.
What system growers use to manage thrips early in the growing season in 2013 is not so important. What is important is that they have a plan and that they manage these insects.
Otherwise, they can expect yield loss and in some cases quality loss, too.
“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.
“In some tests, with the help of a microscope, we sometimes count as many as 200 to 500 immature thrips per 5 seedlings! That’s a ‘ton’ of thrips, especially if seedlings are unprotected. So it’s probably not a surprise that Virginia and North Carolina have the highest ratio of surrounding host vegetation to small average cotton field size,” Bacheler says.
“It’s also not a surprise that growers in these highly susceptible areas better have a good system to manage thrips,” he adds.
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