view current print edition




Florida growers’ woes help others prepare to cope with greening disease

California citrus growers are finding out what Florida and Texas growers already knew: that the biggest threat to their livelihoods may not come from the Asian Citrus Psyllid, a tiny insect that spreads the deadly citrus greening disease HLB, but from homeowners who see their backyards as the best source of fresh citrus.

Southern California has been host to a large population of the psyllid for years. In urban areas — particularlyHLB-3With the use of a transmission electron microscope, molecular biologist Jianchi Chen and technician Darlene Hoffmann, both with USDA/ARS in California, look for bacteria associated with citrus greening disease. (Photo by Stephen Ausmus, USDA/ARS) Los Angeles and Orange counties — many homes are older, and about 60 percent have at least one “and usually more” backyard citrus trees, according to California Citrus Mutual Director of Government Affairs Shirley Batchman.

When Mutual first started looking into controlling the spread of HLB after Florida groves were decimated by the disease over the last decade, researchers realized “the psyllid population had been there a long time and we’d never been looking for it — because we had no reason to look for it,” Ms. Batchman said. “Being the size state we are, having the really dense urban population in Southern California, we found out in the urban population it’s endemic and it had been there for a long time. That’s when we realized we could no longer do backyard treatment, it was just impossible, we needed a new strategy. You draw your buffer lines around this area and treat from the buffer out. There’s no commercial production in there anyway.”

Mutual made the call to virtually evacuate Southern California and focus its efforts on protecting the rest of the state and especially the San Joaquin Valley, one of the world’s richest production areas for a variety of citrus, including oranges, lemons and increasingly popular mandarins.

In the last two years, extensive trapping in the San Joaquin Valley has yielded just three citrus psyllids.

There has been only one known case of HLB in California, found in March 2012 in a lemon tree in a residential neighborhood in the Hacienda Heights area of Los Angeles County. Through thorough investigative and prevention efforts, Mutual officials hope there will be no others.

The lone infected tree had been recently purchased by a homeowner at a church bazaar. The homeowner told Mutual officials who had sold her the plant and a painstaking, home-by-home follow-up investigation showed that no other grafts from the same purveyor were infected.

“There is a CSI element to it, there truly is,” Ms. Batchman said.

There is also a cooperative element, as Texas learned in January 2012, when HLB was confirmed in a lone grove in the Rio Grande Valley. Florida growers’ struggles with the disease have better prepared other states to deal with it. Since the initial discovery, there have been no other confirmed HLB cases in Texas, thanks in large part to information Lone Star growers learned from Florida farmers.

California was paying attention all along.

Said Ms. Batchman, “We were proactive and tried to get ahead of the curve because Florida was so gracious in sharing with us everything they’d done wrong. When we were down there in 2008 they said, ‘This is what we did, it’s wrong, don’t do what we did, you need to consider doing this,’ and we did that at every level. We have benefitted from what they went through, we really have. We’ll see where we ultimately end up.”

Intact psyllids were found in two areas of the San Joaquin, around which there are “quasi-quarantines” in place, consisting of five-mile circles with tightened controls and 800-meter epicenters where more intensive protocols are in place. The initial quarantine period is six months. After that, “if there are no additional finds, they will be removed. If there are, it’s my understanding we will then go into a full-blown quarantine,” Ms. Batchman said.

Because of Florida’s experience and ongoing willingness to share information, “I think we’re much better prepared,” Ms. Batchman said. “If Florida hadn’t opened their doors and laid it on the line for us, we’d have been a couple more years down the road when we [started making preparations] and then we’d have been in real trouble.”