Back in May sugarcane beetles, a little known pest in the Upper Southeast, began popping up in Virginia corn fields.

At that time there were no reported cases of the tiny, mostly subterranean pest in North Carolina. In May and June, North Carolina State Entomologist Dominic Reisig says hot spots of the beetle occurred sporadically around the Tar Heel State.

Reisig says, “It was actually a severe problem in the North Carolina Piedmont this spring, and I found it in the eastern part of the state, as well.” 

It was kind of a wide-spread problem in four or five counties in the Piedmont. Ben Knox, a long-time farmer and agri-business leader in the area identified the problem on several farms in the area. It was the first time in 30 years or so of working with farmers for sugarcane beetle to be such a wide-spread problem,” Knox says.

Most of the damage from this insect on corn occurs when the crop is in the seedling stage. By the time soil temperatures warm in late June and into July, the damage has been done and the beetle moves on to other food sources. Typically, by late June or early July, sugarcane beetles are gone from corn fields.

(For a complete report on the situation as it developed this year, see http://southeastfarmpress.com/grains/sugarcane-beetles-being-found-virginia-corn-crop).

A good production tip for next year’s corn crop is to plan ahead for sugarcane beetle. A number of cost effective management programs are available for fields with a history of sugarcane beetle damage, or those located near fields that received damage during the 2011 crop season.

Reisig says growers who are planting corn behind corn and are near areas used for pastures should be particularly aware of the potential of problems from sugarcane beetles.

“I don’t think the problem this year was confined to the Piedmont, but they have more natural grassland and grow more corn on corn for use as silage, since the area has a number of large dairies,” Reisig says.

Potential recognized

Pioneer has been one of the first companies to recognize the potential severity of the sugarcane beetle on corn crops in the Southeast. Both Ben Knox in the Piedmont of North Carolina and Glenn Rountree in southeast Virginia were instrumental in getting information about the pest to growers.

The company recently published a list of scenarios in their publication, Crop Focus.

In the publication are two planting scenarios that can impact an integrated pest management program for managing sugarcane beetle.

These include: Avoid planting corn into sod or grassy fields. And, avoid minimum or no-till practices in grassy areas.

It is critical to plant corn early, or at least timely according to planting time field conditions and to fertilize properly to encourage vigorous seeding growth. This will help minimize seedling injury, if beetles infest the corn field.

The best insurance against these sporadically occurring pests in corn is to use an insecticide seed treatment. In the Delta researchers have found Poncho at the 500 ppm rate was more effective than Cruiser 500 at the same rate in preventing damage from sugarcane beetle.

Seed treatments will provide some protection from sugarcane beetles, but not excellent plant protection.

High rates (1,250 ppm) may give good to excellent protection under some cropping and weather scenarios, but rates of 250-500 ppm are likely to give fair to poor protection, regardless of which seed treatment is used.

Both granular and liquid insecticides, in combination with seed treatments, may provide adequate protection in fields with a history of damage from these beetles. Other high risk fields are those that have been planted to sod crops or located near sod fields.

These tiny insects are mostly nocturnal feeders and can be both difficult to find and to kill. Typically, even if a grower decides to use one of a number of insecticides that will kill these insects, getting the material to the adult beetle is tough.

Can reduce infestations

Granular organophosphate insecticides such as Lorsban 15G and Counter 15G applied in the seed furrow or banded across the row can reduce sugarcane beetle infestations in field corn.

Seedling injury has also been reduced in field plots treated with a variety of different insecticides as rescue treatments including Capture 2EC, Lorsban 4EC and Baythroid 2EC. In spite of these treatments, however, significant plant injury and ultimate yield losses still occur. 

In corn fields with large infestations of the insect, growers in both Virginia and North Carolina saw severe damage to the corn root system. Young plants are the most susceptible and several fields with damaging populations of sugarcane beetle in corn were reported this year.

Adult beetles mate in the ground during the spring. The female beetle deposits the eggs into groups of three or four eggs in earthen cells. After hatching, the grubs feed upon decaying plant matter in the soil.

After larva develop into an adult beetle, the food preference changes. Adult beetles attack the stems of young corn plants, feeding at or below the soil line. Damage to young corn plants can cause plants to wilt and die. A single beetle can destroy several plants in a row.

As it feeds, the adult sugarcane beetle chews a large gouge in the stem at the base of the plant. Eventually the damage to corn shows up as dead plants, plants with a dead heart, or stunted plants.

The ultimate result of having these little pests in your corn field is going to be reduced yield. How much yield loss is likely to be more dependent on how many beetles are in the field than what a grower does after he finds the insects.

Once you see damage from these beetles there is little a grower can do, says Virginia Tech IPM Leader Ames Herbert.

“These insects feed mostly below the soil surface; they come out for only a few hours at night or in the early daylight hours. While there are plenty of insecticides that will kill them, getting the product to the insect and at the right time is very difficult,” he says.

The best option is to plan ahead, including scouting fields that are planted to corn behind corn, poorly drained and/or near sod fields or planted on ground with a history of sod production.

“In the research plots where I found sugarcane beetle I had 10 pounds of Counter on my corn, and it didn’t seem to make a difference. So, I guess the best management strategy may be to use high rates of an insecticide seed treatment and expect to see some damage in high infestations,” Reisig concludes.

rroberson@farmpress.com