OAKVILLE – A San Francisco-based real estate investor who built a wine business with 550 acres of vines in Sonoma and Napa counties and acquired a former Mondavi winery has filed for U.S. Bankruptcy Court reorganization, citing $13.7 million in debt.

Eight weeks after filing for chapter 11 reorganization for his San Francisco-based Montgomery Realty Group investment companies, Dinesh Maniar filed for similar relief from creditors for his Diamond Oaks Vineyards and Southland Thoroughbred Farms racehorse business on Sept. 14, according to court documents filed in Santa Rosa.

Mr. Maniar and his attorneys – David Chandler in Santa Rosa for Diamond Oaks and Michael St. James in San Francisco for the others – did not return calls asking for comment.

Debts topped $32 million in all four filings. Diamond Oaks has $26.8 million in assets and $13.7 million in debt.

Southland had $6.90 million in assets for five properties in Riverside County and $3.24 million in debt.

Montgomery Realty Group Inc., formed in 1999, has $26.04 million in assets and $15.39 million in debt. Of the asset value, $22.3 million is in two San Francisco office buildings and an Austin apartment complex. In a reorganization plan, Mr. Maniar proposed to give the apartment building back to lender California Mortgage and Realty and use rent from the others to pay debt.

Bank of America won a judgment regarding its note on one of the buildings, according to documents.

Gross lease revenue from those properties decreased from $2.03 million in 2007 to nearly $869,000 so far this year.

Montgomery Realty Group LLC has $18.03 million in assets – Concord Plaza Park & Shop shopping center – and $14.58 million in debt.

Mr. Maniar got into real estate in 1973 with the development of 1.5 million square feet of space in south San Francisco, according to a company securities filing.

Over the past three decades, Mr. Maniar built a wine property portfolio that included five properties in Napa and Sonoma counties, according to the winery Web site. With advice from Robert Mondavi, Mr. Maniar got started in the wine business with the purchase of 52 acres of vines at the foot of Diamond Mountain near Calistoga in 1977 from the Zinc family.

In 1982 he purchased 64 acres south of Cloverdale in Sonoma County’s Alexander Valley appellation and planted 35 acres of it with grapes. The following year he acquired the 93-acre Mina Ranch in Sonoma’s Chalk Hill appellation from Harold Groom Horse Ranch and planted 85 acres of grapes. In 1994 he purchased a 330-acre vineyard in the Sonoma side of Los Carneros region.

Grape sales totaled $1.01 million in 2007, $830,000 in 2008 and $477,600 so far this year, according to court records.

Silverado Vineyards LLC purchased the Carneros and Chalk Hill properties in May 2008 and April 2009, respectively, for $6.08 million apiece.

In 2000 Mr. Maniar and his son Raj started the Diamond Oaks label, made from the family’s grapes. Three years later Dinesh Maniar acquired the 22-acre winery site from Robert Mondavi Corp., which operated it for the Vichon and La Famiglia brands.

A court meeting of creditors in the Diamond Oaks matter is set for Oct. 23  in Santa Rosa.