Insect growth regulator piggybacks with fungicides at the R3 stage and may be adding to plant health in a systems approach.
Arkansas crop consultant Rick Deviney always encourages his growers to push their soybean yields to the max; his producers have averaged as high as 90 bushels per acre. Before the soybean field is planted, he always sits down with his growers to discuss their plan of action for the upcoming season.
“During winter meetings or in a one-onone setting, I will go over what we expect for our fertility, insect, disease and herbicide control programs,” says Deviney of Southern Ag in DeWitt, Ark. “I’m a full-season consultant. I start looking once the crop is planted and look until maturity.
“I make visual inspections to make sure nothing is out of whack. I also take stand counts so I’ll know if there is a missing plant and if it was because of insects. Then our insect management plan goes into action.”
Deviney scouts each field weekly after the soybean crop has been planted. “We have pests like worms or stink bugs that can get in there and really devastate a crop,” he says. “During the vegetative phases of growth, we mainly deal with foliage feeders. Then we start looking for pod feeders because they can really do damage to yields.
“We go by university thresholds with foliage feeders. When it comes to pod feeders, we have our own system that takes a little more thought process.”
Keeping an Eye in the Field
Once soybeans start blooming, Deviney starts sweeping every week doing 25 sweeps per check. Since he also makes fungicide recommendations, he tries to piggyback his insecticide applications with his fungicide applications when possible. “We combine our insecticide sprays with other applications whenever possible because you never want to tell a grower to spray a field one week then come back with another spray the next.
Deviney begins making fungicide applications at R3 soybeans. “Soybeans are a cash crop; they aren’t just a rotational crop anymore,” he says. “So we push producing high yielding soybeans. Last year one of my customers was the first grower in the state of Arkansas to grow 100-bushel soybeans. That really got us hyped up about producing highyielding soybeans.
“We run two-shot fungicide applications on these high-yielding soybeans so there is another trip going across the field there. We have one shot of fungicide at R3 and the other application is two weeks later at R5. That isn’t on every field by any means but only for the producers that are interested in very high-yielding soybeans.”
Since an airplane is already going across the field to apply fungicides, Deviney sometimes will lower his insect thresholds if there is a reason to add an insecticide.
“With stink bugs, for example, often you will scout one week and have a half threshold, and then you come back the next week and still have a half threshold,” he explains. “Over time, they can do a lot of damage, so often, you pull the trigger early on treatment. I bet half the stink bugs I sprayed last year were probably not at a full threshold and a lot of times it was because of the fungicide application on our really good soybeans.”
Identifying Hot Spots
Deviney covers a large area from south of Dumas to Stuttgart so he know the trends and if infestations are coming in from one way or the other. “I’ve been on my growers’ farms for five years now so I also know the hot spots,” he says. “For example, every year worms may come out of a certain patch of woods. I go to that spot first because I know that is where they have always been. You need to catch insects early; armyworms, for example, can march across the field quick.”
Another way he stays on top of insect pressure is by talking with other Arkansas consultants. There are excellent consultants in Arkansas, and by staying in touch, they can see if there is a migration coming up.
“I have a good friend who I see at church every Sunday,” Deviney says. “He works south of us, so a lot of times they are a little bit earlier than we are. Plus, there is the southern migration of many insects. We talk all the time about what we are seeing.”
Insect Growth Regulator
Additionally, Deviney has tried a new insecticide, Cavalier 2L, on his soybeans in three trials. This insect growth regulator’s active ingredient is diflubenzuron. It has shown him a two-bushel increase at a twoounce rate.
“I like what I have seen so far from Cavalier 2L,” he says. “It’s being applied at a time when we are going across the field anyway – fungicides at R3 – so we don’t have to make an extra trip during its application. It fits our program perfectly because we can apply it with the fungicide application at a time when worm pressure is likely coming.
“Cavalier 2L is an insecticide, but we’ve always considered it a fungicide. It has an insect suppression side that has an added benefit. Soybeans are our new cash crop so we look for ways to keep the plant healthy from the time it starts blooming until it matures. Our goal is not necessarily controlling a disease that is present but preventing any diseases from taking place to keep the plant healthy during that important time frame.
“Cavalier 2L may be adding to plant health. At the same time, it hasn’t just been a coincidence that we have not had to treat worms where we have applied Cavalier 2L. A vigorously growing plant is better able to fend off insects as well as disease so it’s all a systems approach.”
Raymat Crop Science submitted this article.