Dr. Calvin Trostle, Professor & Extension Agronomist/AgriLife State Hemp Specialist, TAMU Dept. of Soil & Crop Sciences, Lubbock, (806) 746-6101, ctrostle@ag.tamu.edu

Dupont’s popular insecticide Prevathon is now a product of FMC.  The use instructions for crops and pests are essentially the same.  The percentage of active ingredient ‘RynaXypyr’, or chlorantraniliprole, is much different.  This leads to large changes in the labeled application rates.  Prevathon was 5.0%, Vantacor is 47.85%.

Prevathon became popular for several reasons.  First, there is some limited movement—translaminar flow is what Dupont called it—within plant parts that receive the chemical.  This is not translocation, but movement within a leaf, or a head, other plant part.  I am not aware of university research on translaminar flow, but the chemical must be working as it has enabled producers to address some more difficult insect control issues like sorghum headworm (same as corn earworm and cotton bollworm) in the whorl of grain sorghum.

An additional favorable attribute of chlorantraniliprole is it is ‘soft,’ hence less injurious on beneficial insects and pollinating bees.  This has been a special concern of sunflower farmers where different species of bees are active.  Beekeepers who provide hives for pollinating crops are pleased they do not lose much of their bee population if chlorantraniliprole is used compared to a pyrethroid.  Sunflower researchers were quite keen when Prevathon came to market as research and observations suggested that chlorantraniliprole plus beneficial insects was favorable vs. pyrethroids minus beneficial insects.

Prevathon/Vantacor Mode of Action is Different than Many Other Insecticides

The aspect of Prevathon that made farmers, extension, and researchers initially uncertain about Prevathon was the mode of action.  It targets feeding worms.  It does not stop egg lay.  Worm damage in sunflower, for example, results from adult sunflower (head) moths laying eggs on the face of blooming sunflowers.  These eggs hatch in a few days, larval stages progress while feeding on the head, and some eat the meats out of the kernel or burrow into the head.  This makes the sunflower head susceptible to Rhizopus head rot, which is worse than the direct insect damage.  In sunflower and other crops like grain sorghum when feeding worms ingest the chlorantraniliprole, they stop.

Chlorantraniliprole targets the worms. It allows the egg lay by the moths.  In contrast pyrethroids kill the adults and in theory prevent the egg lay in the first place.  This is like weed herbicides that prevent weed germination in the first place, like a ‘yellow’ herbicide (trifluralin, pendimethalin, etc.) in contrast to a contact herbicide like glyphosate or dicamba that does nothing in preventing weed establishment but targets existing weeds.  It would seem the chlorantraniliprole mode of action would be riskier (and perhaps it is), but on many crops and in control of many feeding insects Prevathon has a history of effective insect control.

How to rates of Prevathon and Vantacor compare?

Comparing rates of these two insecticides’ application rates should be a non-issue because one should follow the new Vantacor label.

But farmers have asked what the comparable rates would be.  This is determined by looking at the percent active ingredient in Prevathon vs. Vantacor:  5.0% vs. 47.85%.  For all insects listed on the label (corn earworm/sorghum headworm, sunflower moth, beet and fall army worms, etc.—the one exception is grasshopper which has a lower rate) across all crops for spray applications, the following table compares labeled rates of the two products with the same active ingredient.

There is no guarantee that the formulation or additives would be exactly the same, and that could explain differences in application rates.  But that does not appear to be the case with Vantacor vs. Prevathon.

The Vantacor label does include specific instructions for the application timing and repeat interval for sunflower moth & banded sunflower moth (application at initial bloom, R 5.0-5.1), and for grasshoppers.

Vantacor Carrier Volume for Aerial Sprays

The labeled minimum rate of water per acre for airplane application of Prevathon and now Vantacor is 2.0 gallons.  AgriLife Extension has long emphasized that for many insecticide applications good coverage is important.  It might be more important than the chemical you choose.  I recommend a minimum of 3.0 gallons per acre for control of sunflower moth in sunflower.  FMC reps I know in Texas and North Dakota who advise on sunflower insect control (and other crops, too) agree 3.0 gallons should be the minimum.  You might have to pay a bit extra to have this done.

Be sure to ask any aerial applicator what gallons per acre they will use with chemical applications you hire.  Ensure that this is at least the minimum labeled carrier volume.  You want to be certain you get what you pay for.