What is in this article?:
- Pheromone traps: an easier way to scout for corn borers
- Savings of time, effort
- Changes in control recommendations
“It would take 90 hours of scouting for southwestern corn borer egg masses to get the same precision you can get with just four pheromone traps," says Fred Musser, associate professor of entomology and plant pathology at Mississippi State University. "I don’t know of anyone who wants to spend 90 hours on making a single decision.”
BEN MERIWETHER, left, Valent USA, Tupelo, Miss., and Rhett Ruscoe, BASF Corp., were among those attending the annual conference of the Mississippi Agricultural Consultants Association.
Savings of time, effort
Musser says it would be necessary to look at more than 10,000 corn plants to get adequate data for accuracy of predictability using the egg scouting method.
“That’s versus four pheromone traps to achieve an equivalent result. I think it’s pretty obvious which choice most folks would make.”
“It would take 90 hours of scouting for egg masses to get the same precision you can get with just four pheromone traps. I don’t know of anyone who wants to spend 90 hours on making a single decision.”
This system allows “a big savings in time and effort, and you still get the quality of data you want,” Musser says.
The cost of a simple plastic bucket trap, plus lure for a season, runs about $14. “If you take care of them, they can last for four years.”
Four traps are recommended per decision unit. “You can make decisions on a field-by-field basis or farm-by-farm basis. You have options on how you want to get your data and on what scale you want to do it.”
Recommendations for trap placement, Musser says: “Avoid trees or anything that blocks wind flow. Place the trap outside the field, not inside — air flow is critical. Keep any grass or weeds from growing tall around the trap and limiting air flow. Replace lures every two to three weeks.”
The Mississippi treatment threshold for southwestern corn borer has been revised, Musser notes. “It was 25 percent egg masses/larvae at the early vegetative stage; now, it’s 50 moths per pheromone trap or 5 percent egg masses. In the early reproductive stage, the threshold is now 100 moths per pheromone trap or 10 percent egg masses.”
A R4 stage or later, he says, “we recommend no treatment — corn will be at dent stage before the eggs hatch and you’re not looking at any economic yield loss. There could be stalk boring and potential lodging, in which case you might want to move up your harvest date.”
In Bt corn, Musser says, “the technology is still working splendidly, and nobody I’m aware of has reported any southwestern corn borer survivors. We hope it will stay that way for a long time.
“The biggest densities we’ve seen of southwestern corn borer have been where non-Bt corn has been planted for several years. In those situations, they can build up locally and become a problem. We saw a number of instances of this in 2013.”