Fresh-market tomato growers and shippers had direct access to both variety trials and University of California specialists during a recent field day at LeGrand.

A test plot within an 80-acre block farmed at the Merced County community by Bill Giampoli was opened for viewing just prior to harvesting.

Nearly 30 green-pick varieties, including round- and roma-types, from American Taki, BHN Seed, LSL Plant Science, Seminis/Asgrow/Petoseed, Syngenta/Rogers/Novartis, Sunseeds, and United Genetics were planted.

UC Cooperative Extension and the California Tomato Commission sponsored the field day.

Scott Stoddard, Merced County staff research associate, said data from the trials was to be gathered shortly after the field day and evaluations would be announced later.

Dodder strategy options

Kurt Hembree, Fresno County farm advisor, one of several UC researchers on hand for poster presentations, offered strategy options for management of the long-time foe of tomato growers, dodder.

Urging growers not to give up, Hembree said proper implementation of several steps can significantly reduce or eliminate the stringy, yellow, parasitic weed over time.

“Another part of a good strategy,” Hembree said, “is using good crop rotation…”

  • Preplant incorporated or pre-emergence herbicides can be applied to eliminate weedy hosts within the plant row during stand establishment.

  • Pre-emergence herbicides, however, have little impact on controlling dodder seed.

  • Planting after June 15 will avoid the majority of dodder seed germination.

  • Varieties known to have resistance to dodder can be used in fields that have mild or new infestations.

  • Early season weed control, including hand removal or treating with glyphosate, can eliminate small, escaped weeds. Infected plants should be removed from the field and destroyed.

  • Timely cultivation can reduce the risk of weed host survival, while sanitation along field borders and roadways can eliminate dodder plants and seed sources.

  • A mid-season walk-through can eliminate escaped dodder plants before they can set flowers or seed. Again, infected plants should be removed from the field and destroyed.

Crop rotation

“Another part of a good strategy,” Hembree said, “is using good crop rotation, by planting non-host crops like cereals, cotton, or resistant tomatoes. Do not plant host crops like onions, safflower, melons, sugar beets, or legumes unless there are control options available, such as in alfalfa.”

Hembree reminded that monitoring for weeds is a key component in a successful weed management program. Growers can record observations by walking several locations, perhaps three times a season, and listing broadleaf, grass, and perennial species.

Monitoring, records

They then can map areas of concern, adjust the treatment program as needed, and keep records of treatments and results for future reference.

The California-grown, fresh-market tomato crop in 1999 was slightly more than 40 million, 25-pound cartons harvested from about 44,000 acres. California produces nearly a third of the nation's output and is second to Florida.

In 1999, San Joaquin County was the leading producer, with more than 11,000 acres. Other major acreage counties were Merced, 9,000; Fresno, 6,500; and San Diego, 4,300.

e-mail: dbryant@primediabusiness.com