With unseasonably warm weather and a lack of rain this winter, local winegrape growers worry grape buds will break too early, resulting in a reduced crop.
Camron King, executive director of the Lodi Winegrape Commission, said a number of factors have local winemakers concerned.
“The fact that the warmth has forced a lot of buds to break early and has the potential to cause frost damage is a big concern for growers,” he said.
Grapes buds usually break in the spring after being dormant during the winter, but temperatures in the high 60s and early 70s the last few weeks have some growers worried about early bud breaks.
The beginning of a grape’s growth cycle is called “bleeding,” and usually starts when vines are pruned in the winter. Bleeding occurs when soil warms up and water is pushed from the root system through cuts in the vine. Grape buds then typically break and begin to grow in the spring.
Tom Hoffman, owner of Acampo’s Heritage Oak Winery, said he expects his grapevines to start bleeding in next few weeks, about a month before the first day of spring.
Hoffman added that he is seeing signs of spring along the portion of the Mokelumne River that flows near his 160-acre property.
“As the vines begin to grow in this warmer weather, that means the grapes will grow too soon,” Hoffman said. “And the warm weather we had last week was alarming to me.”
Last week’s daytime temperatures reached the 70s. While temperatures are expected to drop into the 50s this weekend, the area is expecting warmer numbers in the next two weeks, according to AccuWeather.com, a private weather forecasting service.
Paul Verdegaal, a farm adviser at the University of California, Davis extension in Stockton, wrote tips earlier this week for local growers in times of drought on the Lodi Winegrape Commission’s website.
Verdegaal writes that dry soil creates dry roots that can result in erratic budbreaks and delayed or advanced water push. In addition, vines can experience drought-induced Boron deficiency, which includes erratic, slow, distorted stem growth. Some leaves may also start to shape into crinkled fans with prominent veins. Other effects drought can have on grapes include potassium deficiency and increased nitrogen absorption, he said.
His tips can be found at www.lodigrowers.com/cold-and-dry-thoughts.
Hoffman said he wouldn’t know how this year’s dry weather would affect his grapes until their buds begin to break. But he said wineries can expect to see a reduced crop this year.
His biggest concern is the reliance on groundwater to maintain his grapes.
“I have had to irrigate this month, and I’ve never had to irrigate in January,” he said.
Local agencies such as the city of Lodi and the San Joaquin County Public Works Department have been encouraging water users — both residents and commercial customers — to conserve as much groundwater as possible.
But without rain, and in order to have a successful crop, grape growers may be forced to use their groundwater supplies throughout the year.
The North San Joaquin Water Conservation District has 131 groundwater wells under its authority.
According to a 2013 groundwater report conducted by the San Joaquin County Flood Control and Water Conservation District, of 109 of the NSJWCD wells that were monitored, 62 wells saw water level increases from 2012 to 2013, while 46 wells saw decreased levels.
With Gov. Jerry Brown’s declaration of a dry year last week, it is anticipated many water districts will see reduced water flows from nearby rivers, which will mean less water transferred to groundwater wells for storage this year.
King said several members of the Lodi Winegrape Commission will soon be asking the state legislature to review its policy on water distribution during dry years.
“(Addressing the legislature) highlights the agricultural and water availability needs of not just winegrape growers, but the farming community in general,” he said. “I mean, everybody’s happy we’re getting a little rain this week, but it won’t solve our drought or warm weather concern.”
Contact reporter Wes Bowers at email@example.com.