Bottle sprayer invention offers lab, field tests of insecticides
When it comes to application of crop insecticides to row crops, getting the most for your money often boils down to finding the answers to the right questions, says a Texas AgriLife Research expert.
Christian Nansen, AgriLife Research entomologist at Lubbock, says success often hinges on knowing how long a treatment will last (its residual effect), if adjuvants (substances enhancing effectiveness) will make the treatment last longer, and whether or not the spray placement and penetration deep into the crop canopy is important.
“Controlled uniform applications are key aspects of finding answers in insecticide performance research,” Nansen says. “When doing experimental work with insecticides in the laboratory or in field plots, we need to be able to apply known and accurate insecticide dosages to individual crop leaves to determine their optimum effectiveness against target pests.”
Until now, Nansen says finding those answers under field conditions has been a logistical nightmare, especially on the High Plains’ windy and dusty conditions, and because they have not had the proper equipment for field-testing of insecticide applications.
• “Bottle sprayer” gadget helps ensure a uniform and effective spray pattern.
• Texas AgriLife Research invention can test spray efficiency in a lab or at a field.
• Spray test can analyze an application to different leaf positions in the canopy.
Gadget not expensive
Nansen and team solved the problem by developing a simple, inexpensive device they merely call the “bottle sprayer.” Their invention consists of a 2-liter plastic soda bottle with the bottom removed and an artist’s airbrush mounted inside the top. The bottle is connected to a wooden frame, and a small carbon dioxide air cylinder operates the airbrush. The unit costs under $400.
They have calibrated the device to know how much formulation is being delivered under different air pressure conditions to simulate what is being applied under commercial applications.
“The airbrush acts as a miniature spray nozzle, while the bottle keeps the resulting spray pattern confined within a small measured area,” Nansen says. “The whole unit is portable and great for field use. And with the soda bottle protecting the spray pattern, it doesn’t matter if the wind is blowing or if there’s dust.”
Nansen says the bottle sprayer is ideal for testing a number of pesticides quickly, which is critical when producers are faced with a new little-known pest, or need rapid screening of a series of insecticides.
A great example is Nansen’s work with the potato psyllid, an insect implicated in zebra chip disease, caused by Candidatus liberibacter bacteria. Producers can’t sell infected potatoes because when the tubers are fried, consumers find the resulting dark discoloration unappealing. The disease has cost Texas potato producers millions.
Using the bottle sprayer, under both laboratory and field conditions, Nansen found one insecticide, Agrimek, to effectively control adult potato psyllids. His research team used the bottle sprayer in field plot tests in applying Agrimek to individual potato leaves at different positions within the canopy.
By using the bottle sprayer, Nansen was quickly able to show Agrimek lost its effectiveness within a few days after application due to the sun’s ultraviolet rays breaking down the insecticide. That finding suggests there is great need to look into how the insecticide can be applied, so that it penetrates deep into the canopy and thereby is protected from sunlight degradation.
The goal is to develop application methods for the insecticide to be applied to the underside of the crop leaves to increase residual effect, and psyllid mortality, as the psyllids tend to feed and lay eggs underneath potato leaves.
By using the sprayer gadget, Nansen and colleagues were able to determine that the application method was the main constraint regarding effective use of Agrimek. So the trick in this instance is to apply the insecticide under the leaves and out of direct sunlight.
You can reach Nansen at firstname.lastname@example.org.
Byrns is with Texas A&M Communications, San Angelo.
This article published in the June, 2010 edition of THE FARMER-STOCKMAN.