Bye, Bye, Bugs

This week, Imperial Valley farmers are beginning what should be a nearly normal harvest of their winter vegetable crop.

That hardly seems like earth-shaking news--unless you’ve been following the travails of this hard-tested agricultural community.

Located on the Mexican border just 50 miles or so from Arizona, the valley was the first California landing spot of the “Super Bug”--the poinsettia strain of the sweet potato whitefly. Last year, clouds of the pests descended on the area, causing $120 million in crop damage, and wiping out the fall melon crop--normally the nation’s largest.

The flies suck the nutrients from the leaves of plants, weakening them or even killing them. They also leave behind a sticky, sweet residue that encourages sooty mold, a fungus that further weakens plants.

This year, the fall melon crop moved elsewhere. In 1992 12,000 acres of melons were planted. This year that dropped to less than 100 acres. Central Arizona and northern Mexico picked up the slack.

Actually, that hiatus--combined with a similar one by cotton growers--may be the valley’s savior. After this year’s spring melon harvest, farmers plowed under the plants and weeds that might provide shelter to the pest. In addition, rather than planting in the heat of September, as they normally do, farmers this year waited until cooler weather in October.

“It took a concerted effort on everyone’s part,” says Bruce Sanbonmatsu, president of Sanbon, a grower-shipper. “And for a while, it looked like even that wasn’t going to be enough. The whitefly population in September looked very high. You could just drive off and your windshield would be covered with them. But then, as soon as the night temperatures started breaking, that combined with a lack of host crops, the whitefly population dropped like a stone.”

This winter’s plantings of broccoli, cauliflower and lettuce are about 30% lower than last year, but that reduction is not totally due to the whitefly. Because of the delay caused by the bug last year, the Imperial Valley’s winter vegetable harvest bumped up against later harvests around the country, creating a glut that resulted in disastrously low prices--by itself enough to dissuade many farmers from replanting quite as extensively this year.

But despite a somewhat later start, this year’s crops should be on time and they look healthy, says Keith Mayberry, cooperative extension farm advisor with the University of California. “We’ve got nice, uniform-looking green fields for a change.”