If it weren’t for growers in Palm Beach County, much of the country would go without succulent, fresh sweet corn. Paul Allen, vice president and partner with R.C. Hatton Farms, Pahokee, and president of the Florida Sweet Corn Exchange, says the county is the largest producer of fresh sweet corn in the country.

“There are 20 growers in the county who produce 30,000 acres in a given year,” he says.

To remain top of the list in terms of production, growers have to keep a watchful eye out for pests that can destroy their crops. The fall armyworm and silk flies are the two that remain the most devastating and common year after year. Most growers use scouting methods, as well as other measures, to stay on top of these two pests.

Scout for the first sign of infestation

R.C. Hatton Farms’ 4,500 acres of sweet corn in Florida and Georgia are scouted twice a week—three times a week when insect populations are high—so the farm managers can take care of their fields accordingly, Allen says. The company uses Glades Crop Care out of Jupiter to do this.

“We check 50 percent of the blocks in a given day and they will count 100 ears of corn (or plants if the ears aren’t there yet if the plant is young) and give us a percentage,” he says.

Allen says each grower has a threshold of insect populations he can maintain before the scouting company will recommend treatment.

Charles Mellinger, director of technical affairs for Glades Crop Care, says the company scouts sweet corn two times a week during the whorl stage and three times a week during the silking and ear development stage, which occurs during the last three weeks of the season. “We have developed a sampling system over the years where we sample so many ears of corn per so many acres. We have been in business since 1972, and we have a pretty good track record of performing high quality services,” Mellinger says.

Tom Perryman, crop manager for the Loxahatchee-based Hundley Farms Inc., says the company also uses Glades Crop Care for its scouting. “They are a second set of eyes on the crop. We all look at it too, and we see things, but they take care of our worker protection safety recordings and handle a lot of the paperwork for us so we can spend more time in the field growing and managing the crop,” he says.

Spray when the time is right

Perryman says Hundley Farms uses the scouting reports and recommendations to know when the time is right to apply pesticides. The company uses aerial applications when spraying is necessary, he says.

“By integrating the scouting reports with our aerial sprays, we are targeting our fields that have the problems and not making unnecessary sprays as a preventative measure. We apply product where it is needed most,” Perryman says.

Mellinger says scouts can see the fall armyworm egg masses and all the stages of the insect. Scouts report egg masses and in-stars. There are generally four or five in-stars in the lifecycle of the armyworm. “The goal is to spray the first and second in-star because you can control the population much better,” he says.

With silk flies, scouts can see the adult flies in the fields but they more commonly identify the presence of silk flies by seeing the few silks that are cut by the silk fly maggot feeding. (The flies lay eggs that hatch as maggots. The maggots move down into the ear and start feeding on the corn.) “When you see that, you need to make an application pronto!” Mellinger says.

He says that most of the pesticide applications in the Belle Glade area are aerial, as with Hundley Farms. But some growers are turning more attention to ground rig applications because the pesticide can be placed on the target ear with more accuracy than by air. Allen says R.C. Hatton uses ground rigs on smaller blocks of its sweet corn.

Mellinger says it’s important to note that scouts also recommend when not to spray.

“It is just as important to postpone a pesticide application as it is to make a pesticide application and to double up on applications when pest pressure is heavy to end up with a high quality, marketable corn crop,” he says.

If not controlled, fall armyworm feeding can make corn ears unmarkketable.
• Photo courtesy of the University of Georgia; www.bugwood.org

Additional measures to keep pests under wraps

Perryman says growers can employ some crop aesthetics to help keep pest populations down, for example keeping ditch banks mowed and not having culls lying around.

Mellinger says silk flies tend to live in refuse over the summer months, so keeping refuse to a minimum is essential. He says Gregg Nuessly from UF/IFAS is conducting research involving minimizing trash refuse areas around fields to keep pest populations down. Nuessly also is looking into some products that may repel silk flies from landing on the silks, Mellinger says.

Allen says it also is important to keep weeds down in the off-season. The company also uses methomyl granules—granules coated with the insecticide ingredient methomyl—during the cultivation process. The granules are formulated by Glades Formulating Corp. in Florida and placed right in the top of the whorl of the plant.