Viruses Devastate Lettuce Crop

Salinas Valley lettuce growers are tallying their losses from a set of plant viruses that continue to increase in frequency and intensity across the region.

“It was a disaster as we wrapped up the year,” said Salinas Valley lettuce grower Mark Pisoni. “I’ve seen 20-acre fields without a single head of lettuce harvested.”

As word of the widespread outbreak spreads, lettuce growers in the low desert of southern California and southwest Arizona planted lettuce earlier than normal. Some of those lettuce crops are being harvested this week as growers try to capture record-high lettuce prices. The U.S. Department of Agriculture reports iceberg prices above $90 per box, with romaine prices trailing that by a few dollars per box.

What caused this?

Laboratory tests of lettuce plants point to Impatiens Necrotic Spot Virus (INSV) and Pythium wilt, according to Steven Koike, Director, TriCal Diagnostics in Hollister, California. Koike admits that disease diagnosis can be confusing in that the symptoms resemble each other. This can make it difficult to determine the primary cause of death for the lettuce plant.

The two pathogens largely responsible for the lettuce deaths happen independently, but one may encourage the other. INSV is an insect-vectored issue brought on by Western Flower Thrips. This can make insect control difficult.

Crop crash

The Grower-Shipper Association is working to gather information for the Monterey County Agricultural Commissioner’s office, which compiles data on crop production for its annual crop and livestock report. The numbers from this summer’s INSV outbreak should be reflected in the annual crop report when it is released next year.

“It’s still too early to tell the extent of crop losses,” Mary Zischke with the Grower-Shipper Association told the ag commissioner’s office. She estimates that of the 20% of lettuce acreage in the Salinas Valley thought to be impacted by INSV this year, about one-third of that was lost from the crop disease. Regardless of the cause of the disease, lettuce with disease symptoms like this never makes it to market.

Consumer impacts

Consumers are seeing the impacts of high lettuce prices, which Zischke says could last into December when the desert lettuce harvest begins to fill the marketplace. Some desert growers were already starting to harvest lettuce in early November to help meet market demand.

USDA reports show iceberg and romaine lettuce to be in high demand. This took iceberg prices in early November above $90 per box, with romaine prices trailing by a few dollars. This is reflected in lettuce prices at the store for products that are still available.

Joe Castaneda, owner of the Dog Haus, a Yuma, Arizona restaurant, recently said that he was still able to source lettuce from California but was uncertain if he could resupply. His last price for lettuce was $73.25 per box.

Anecdotal reports showed some restaurants unable to buy lettuce, notifying customers of this as they order hamburgers and other items that commonly come with lettuce.

EDITOR’S TAKE:

When diseases like INSV invade a crop as it did in the Salinas Valley, the results are devastating. It is clear that there currently are more questions than answers about what is causing this catastrophic loss. Researchers will move into high gear to find a solution. In the interim, growers are looking for workarounds that help them salvage a crop and meet strong consumer demand. The overall impact on farmers and consumers is yet to be determined, but should prices for lettuce continue to rise, consumers are likely to cut back purchases. Lower demand would then lead to lower prices at the farm gate. Lower prices coupled with reduced production output could have a very negative impact on growers in that region! Good time to emphasize your service and parts specials.