Punk haircuts have come to California alfalfa. Drive through the San Joaquin Valley and you'll see Mohawks, razor cuts and reverse bowl cuts.
“They're doing it for lygus management,” says Shannon Mueller, forage crops farm advisor for Fresno County. “By leaving some of their alfalfa uncut, the growers are helping prevent lygus from migrating into neighboring cotton fields.”
Lygus are not an economic pest in alfalfa because they don't feed on the vegetative parts of plants. But they're one of the primary pests in cotton.
Leaving alfalfa uncut comes at a price. In controlled field trials, Mueller determined that crude protein levels in the strips declined four percentage points — from 20.6 to 16.5 in 2000 — and TDN declined three percentage points — from 52.7 to 49.6.
“It has an effect,” agrees Cannon Michael, manager of Bowles Farming, which has roughly 4,000 acres of alfalfa and 6,000 of cotton near Los Banos. “We take about a 40% discount on that hay.”
In Michael's case, that loss is offset by the increased profits in cotton. But many alfalfa growers don't grow cotton. And Michael instructs his cutting crews to leave strips anytime they're adjacent to a cotton field, whether the cotton is his or a neighbor's.
In those cases, “people are being neighborly,” reports Pete Goodell, University of California extension IPM advisor. “In some cases, a cotton grower might pay his neighbor to leave a strip in his alfalfa, or he might agree to buy the alfalfa, or do some other favor.”
Growers use several methods to leave strips, says Goodell.
A common one is to leave a 14-18'-wide swath — the width of a cutter bar — around the perimeter of the field. Another option is to leave irrigation pipes in place when harvesting. The harvester can run to within 18" of pipes on each side, resulting in 3'-wide strips throughout the field without having to move the pipes before and after harvesting.
Other growers leave strips in fields wherever they want them. Or they cut fields in half, managing each section so that it's cut and harvested one time, then the other half is cut and harvested 14 days later.
“With as much alfalfa as we have out here, there's always a fresh crop for lygus to go to,” says Steve Smith, who has 1,100 acres of cotton and 1,300 of alfalfa outside Madera. “I'm not sure how much of this we need.”
Even so, Smith leaves strips of uncut alfalfa along each irrigation border.
A key question, says Goodell, is what growers are doing with the hay in their strips.
Smith feeds the strip hay to his beef cattle. “Those are Brahma crosses out in the desert — they're just happy to see anything green,” he says.
Michael sells his strip hay to the dairy market, but not for producing cows.
“This goes to dry cows and heifers,” he reports. “There's so much high-quality hay out here that dairies sometimes have trouble getting the poorer-quality hay for their heifers.”