What is in this article?:
- Carson Smith big on Central California wine grapes
- Adding diversity
- Lending a hand
- Carson Smith Farming Co. co-owns and manages 800 acres of grapes in southwest Madera County along the San Joaquin River.
Carson Smith standing in a Muscat Alexandria block, two years after planting on Freedom rootstock. The vines are planted on a 10-foot row spacing with the vines 6-feet apart within the rows. The cover crop is a blend of bell beans, Dundale peas, common vetch and Cayuse oats.
Smith, who also serves as president of the San Joaquin Valley Winegrowers Association and as a member-at-large on the board of directors of the California Association of Winegrape Growers (CAWG), began his career in agriculture in 1973, selling farm equipment. That was after graduating from Fresno State University, where he majored in agricultural economics. Two years later, he was working with a farm management company, based in Fresno, and learning how to grow wine grapes.
Today, Carson Smith Farming Co. co-owns and manages 800 acres of grapes in southwest Madera County along the San Joaquin River. This is his 17th season for managing that operation.
At one time, the vineyards included 755 acres of French Colombard and 45 acres of Ruby Cabernet. However, to take advantage of changing markets and spread out the harvest work, Smith replaced 200 acres of the French Colombard vines with 100 acres each of Chardonnay and Muscat Alexandria. Continuing this diversification, Smith is replacing another 140 acres of Chardonnay with Pinot Grigio this spring.
He has no access to surface water, relying solely on groundwater to irrigate his vines. With an adequate supply of groundwater Smith has not had to drill any new wells. That’s contrast many San Joaquin Valley growers. However, since 1998, he’s been treating his water with sulfuric acid to reduce pH levels to around 7.0. Otherwise, pH would be in the range of about 7.7 to 8.1, impeding water infiltration and causing salts to build up in the soil.
Smith flood irrigates his older blocks. In the fields where he replaced older vines with new ones, he reduced the spacing between rows from 12 feet 10 feet and added a drip irrigation system. However, he floods these blocks several times each year to flush salts out of the root zone.
Facing a new crop threat
Powdery mildew is the most consistent threat to Smith’s crop. Lately, though, he’s also been keeping a wary eye on red blotch, an emerging threat to growers throughout California’s wine grape country. This viral disease was first observed in California five years ago. Some symptoms of red blotch are similar to leaf roll. In fact, researchers suspect that this particular virus is the real cause of damage previously attributed to viruses that cause leaf roll disease and fan leaf. Red Blotch can reduce grape sugar levels by as much as 5º Brix.
“Fields infected with the disease either don’t get as ripe as wineries want or they’re the last fields to ripen. There are many variables when it comes to the severity of the effects of Red Blotch including climate, vine health, grape variety, and possibly which strain of red blotch is present.” Smith says.
Like any viral disease, there is no cure for red blotch and researchers have not verified how it is vectored. “It is best to start by using virus-free grapevine nursery stock when planting a new vineyard or when replacing infected vines in an existing vineyard,” he explains. “Within the Farm Bill that the CAWG pushed for, we were successful in helping to get language included that funds the National Clean Plant Network. That’s important to ensure an adequate supply of clean grapevine nursery stock.”