Sweep helps protect No. 1 cash crop

Chelle Delaney

A sweep net may be one of the farmers’ best tools to protect and improve alfalfa crop yields, said Mark Muegge, entomologist specialist from the Texas Cooperative Extension office based in Fort Stockton.

Muegge demonstrated how to sweep sample insects from an alfalfa test field Friday at the Pest Scout School at the NMSU Agricultural Science Center in Tucumcari.

“It’s best to see the culprits,” Muegge said.

The focus was on pest management in alfalfa crops because alfalfa is New Mexico’s No. 1 cash crop and, locally, alfalfa hay accounts for one the largest crops in the Arch Hurley Conservancy District, said Leonard Lauriault, NMSU forage agronomist.
There were about 9,000 acres of alfalfa in the district last year, Lauriault said. And prior to the onset of 2001-2002 drought, there were about 14,000 acres of alfalfa hay and another 14,000 acres in pasture, including alfalfa, which represents about two-thirds of the acreage in the irrigation project, Lauriault said.

In 2007 alfalfa averaged about $180 per ton, Lauriault said.

Scouting for and protecting alfalfa from pests means that farmers can protect their crop yields.

Temperatures during the first two weeks of June in the Tucumcari area averaged 75 degrees, 8 degrees warmer than the same period last year. And in 2007 temperatures were slightly higher than the long-term average, Lauriault said.

Combined with the evaporative winds and heat, farmers are seeing their crops maturing faster and insects proliferating, Lauriault said.
As part of the pest scouting procedure, Muegge draws a grid on the bottom of a shallow plastic pan that matches his sweeps of a field. After counting the pests, he inks in the number on the grid. Depending on which and how many insects are found at certain stages in the growing season, a farmer can determine what recommended action to take, Muegge said.

During Muegge’s brief sweep demonstration dozens of insects were gathered into the net. They ranged from beneficials such as the Lady Beetle to pests like the spotted blister beetle, which in large enough quantities can harm livestock.

Blister beetles have been seen in alfalfa crops in the area, but are generally not in quantities to be of concern, Lauriault said.

Certain pests, such as the granulate cutworm, should be looked for in the evening or at night, because they are night feeders, Muegge said.
Aphids are one of the most prolific pests that concern farmers in the Tucumcari area, but farmers still have to be vigilant to ensure that other pests do not have an economic impact, Lauriault said.

As far as pests are concerned,“You have to be on the watch because conditions can change overnight,” Lauriault said.

Lauriault also reviewed various alfalfa crops and growing conditions that are being tested. Alfalfa field tests on seven acres at the center range from renovation-rotation, to alfalfa termination and nitrogen recovery, to irrigated versus dry land fields and to herbicide treatment, Lauriault said.
To learn more about alfalfa production and pest management, call NMSU forage agronomist Leonard Lauriault at 461-1620 or Quay County Agent Tom Dominguez at 461-0562.