Acephate, the active ingredient in Orthene, is able to get into the plant regardless of how it's applied, according to new research at the University of Florida.
In tests, University of Florida weed scientist Greg MacDonald found that cotton absorbed, translocated and metabolized Orthene in various applications such as soil drench, foliar and directed sprays.
In other extensive tests in Alabama, Georgia and Virginia, researchers have found that adding products such as Orthene as a foliar spray over-the-top of a seed treatment decreases thrips pressure and increases yield.
Some of the acephate, the active compound in the Valent insecticide, converts to methamidophos after it gets into the plant's system.
In the Florida study, the objective was to look at how Orthene was absorbed, translocated and metabolized with respect to both acephate and methamidophos. “It was the conversion of acephate to methamidophos we wanted to look at,” MacDonald said at the 2003 Beltwide Conferences in Nashville, Tenn. MacDonald and Robert Querns, also of the University of Florida, looked at Orthene at the fourth-leaf stage of cotton under greenhouse conditions, using foliar, soil drench and directed sprays. The plants were harvested at 24, 48 and 72 hours after treatment with Orthene. The plant tissue was sectioned into leaves, meristem, stem, and roots with each section ground down and analyzed.
“After 72 hours, both acephate and metamidophos can be found in all parts of the plant with the foliar applications,” MacDonald says. With the soil drench and directed spray acephate and methamidophos was uniformly distributed in the plant within 24 hours and over time, with the majority in the leaves and meristem, MacDonald says. “The significance of that is, it's where it needs to be.”
“This movement of Orthene from the directed spray appears to be very similar to the soil-drench application,” MacDonald says. “There was not as much conversion from acephate (Orthene) to methamidophos in the directed spray or soil drench application as observed in the foliar spray.” Movement from the foliar spray was more in the form of methamidophos while movement from the soil drench and directed spray was in the form of acephate. However, movement within the cotton plant is available in both active forms, regardless of application.
In Virginia, Extension Entomologist Ames Herbert has worked with Orthene and other products, using different rates and application times from the early, first true leaf to the two to three leaf stage. “We've seen consistent performance with Orthene as well as other products,” says the Virginia Tech Extension entomologist. “Orthene offers good thrips control.”
“We do see a general increase in yield when we put a material such as Orthene over-the-top with seed treatments,” Herbert says. “In general, the cost of the product is not that great. It can be tank-mixed with a herbicide. If the timing is right, it's a double benefit.
“This applies to some of the other options that are out there,” Herbert says. “We're seeing good response with some of the pyrethroids for thrips control, fitting them into over-the-top sprays.”
Research by MacDonald, in conjunction with research from others such as Herbert, explains how and why Orthene works effectively and why it has a good fit for thrips control in cotton.
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