Late spring rains and cooler growing temperatures have led to an overall drop in agricultural production in San Joaquin County for the second straight year.

The value of farm production was $1.96 billion countywide during 2010. That’s a 2.02 perecent decrease from 2009 when production barely topped $2 billion.

But while some crops were hit hard by unexpected weather changes – asparagus production dropped 46 percent while tomatoes fell 42 percent – others saw sharp increases during the same time frame.

According to a report prepared by San Joaquin County Agricultural Commissioner Scott Hudson, silage corn production went up 115 percent and milk climbed 32 percent to become the biggest product in San Joaquin County this past year.

Walnuts and almonds also saw double-digit growth.

And while Sonoma and Napa counties are widely regarded for their wine production, it’s San Joaquin County that tops the state list for overall wine grape acreage. The county is listed as third in total value in the 75 wineries served here in the local area.

The value of the wine grape crop is estimated at $250,000,000.

In the last 15 years, the acreage that growers have dedicated to wine grapes has more than doubled in the county and has forced Hudson’s staffers to pay close attention to the pests that could destroy the extremely valuable harvest.

An extensive program to monitor for the European grape vine moth and the glassy-winged sharpshooter has been launched. Special focus has been given to the grape vine moth since two were discovered last year in a vineyard east of Lodi. It triggered a quarantine in the five-mile radius from where it was discovered.

But in the agricultural areas in the South County, several of the more recognizable crops and products were listed in the top 10 this past year. Milk topped the list, while almonds came in fifth and hay was listed in eighth place. Silage corn rounded out the top 10.

According to Hudson – who presented the report to the San Joaquin County Board of Supervisors on Tuesday – the majority of the crops that saw a significant decline were susceptible to the bizarre growing season that has affected farmers over the last 12 months.

Both blueberries and cherries saw a double-digit drop along with asparagus, peppers and tomatoes – most of which, Hudson said, were raised by specialty growers in the county.