County growers say whitefly doesn't pose threat to local crops.

Agricultural officials in San Diego County say the whitefly that is ravaging food crops in Imperial County poses virtually no threat to agriculture here. The whitefly has existed for years in this county without getting out of control, they said.

The only serious worry here now seems to be that the highly profitable poinsettia industry in North County will suffer from the misleading name -- "poinsettia whitefly" -- given to the pests damaging the crops in Imperial County.

The Poinsettia Growers Association, started just this month by growers in North County, has hurriedly kicked off its first campaign. It is telling the media and consumers to have no fear that the whiteflies will be spread by potted poinsettias purchased for the holidays. Poinsettia crops are the healthiest ever, the group says.

About 90 percent of the world's poinsettias can trace their roots to cuttings sold by the Paul Ecke Ranch in Encinitas. The flowers, sold during the six weeks of mid-November to December, were a $31 million industry in the state in 1990.

Entomologists say the whitefly doing most of the damage in Imperial County should be referred to as the poinsettia strain of the sweet potato whitefly. And "poinsettia strain," they say, is misleading because it was an arbitrary label of a strain of the whitefly that is also found on hundreds of other plants.

"There's no such thing as a 'poinsettia whitefly,'" said Karen Robb, the farm adviser for flower crops at the University of California Cooperative Extension in San Diego. "This strain of the sweet potato whitefly was first found on hibiscus. It's been in San Diego County and throughout the state for about five years."

There are many reasons why local agricultural officials do not expect the whitefly to be a serious threat in San Diego County. First, San Diego's agriculture does not offer the mass acreage of monoculture -- huge crops of a single type of plant. And the climate here is not warm enough now to effect an explosion in the whitefly population. Also, experts say, there is little chance that clouds of whiteflies will blow westward with the Santa Ana winds and attack crops here.

"We have some of the same crops here, like tomatoes, that they have in Imperial County, but not in the same volume," said David Kellum, supervising entomologist with the San Diego County Department of Agriculture Weights and Measures. "But it's unlikely we'll see the whiteflies coming over here in force from Imperial County. The problem, if there is one, might be with someone bringing over large quantities of infected material."

But even then, agricultural officials say, the whitefly can be more easily controlled in this county because crops are not large and the flies can be eradicated more easily before their populations explode and affect neighboring crops, which are spread much further apart in San Diego County.