Larvae threatens wheat crop

By Mike Linn: CNJ news editor

Thanks to a soggy summer and unseasonably cool fall temperatures, the area wheat harvest is being threaten by a pre-beetle grub that feasts on the plant’s roots.

The cool weather for the last month and above average rainfall in eastern New Mexico created prime soil conditions for wheat diseases and insects, said Mark Marsalis, an agronomy specialist with New Mexico State University’s Agricultural Science Center north of Clovis.

“We’re seeing poor stand establishment at several locations in Curry County,” he said of the crop. “Some fields have a patchy appearance with large areas of either no seedling emergence or seedlings that died soon after emergence.”

The grubs are at the larval stage of a common insect, the June bug, and will rest about 10 inches below land’s surface until temperatures heat up again in the spring, Marsalis said.

When temperatures do heat up again, the white, C-shaped grubs will again feast on the roots of wheat, much like they had earlier this fall.

“They’ll eat just about anything,” said Monti Vandiver, extension agent and integrated pest manager in Bailey and Parmer counties. “Most of our damage will probably be this fall. Hopefully this spring the wheat will be aggressive enough growing that when the grubs come back up and start feeding they won’t be able to hurt the wheat then.”

Vandiver said last spring the grubs destroyed between 120 and 180 acres of potato crop in Parmer and Bailey counties. He said this fall the grubs have done some damage — usually in one to 10-foot circles in a field — to wheat farms in West Texas.

He said the later a crop is planted the better protected from the grubs.

After the spring the year-old larvae will turn into the beetle, and then lay eggs over the summer.

Marsalis said crop rotation is “highly recommended” to reduce insect infestation and disease. He recommends treating seeds with a fungicide to help reduce disease, especially after reseeding into damaged areas.

“Seed treatments are relatively inexpensive and could mean the difference between a well-established stand or a poor stand requiring reseeding,” Marsalis wrote in a recent report.

The grub has been a rare sight over the years due to drought conditions, but have resurfaced thanks to above-average rainfall, said Stan Jones, Curry County’s Ag. extension agent for the past seven years.

“It’s the first time I’ve ever seen it happen,” Jones said. “It’s been more prevalent in the middle of a green wheat field.”
Jones said the larvae appeared on covered cropland, which he estimated protected the beetle’s eggs.

Typically, the grubs eat in groups and will cut circles in a farmer’s land.

“It will be completely bare, a whole circle area,” he said.
This year’s winter wheat crop is estimated at 7.8 million bushels, an 86 percent increase over last year, according to the New Mexico Agricultural Statistics Service. Only 140,000 of the 500,000 acres that were planted were harvested last year because of the drought.

This year, producers planted 490,000 acres and expect to harvest 300,000 acres.

The Associated Press contributed to this report.