Wain Johnson, instrumental in reintroducing wine grape production to Mariposa County, retired from a 20-year career with University of California Cooperative Extension for the county, effective July 16.

Since his appointment to the one-person department in 1981, he served not only as the grape, olive, and livestock farm advisor but also as county director and 4-H advisor.

Johnson spent much of the last 10 years working on control of yellow starthistle, a serious weed pest for livestock, and will continue work on regional management of the problem after retirement.

A native of San Diego, Johnson formerly served with Cooperative Extension of New Mexico State University, where he earlier earned bachelor's and master's degrees.

The Mariposa area had a wine grape industry in the 1870s, but after Prohibition, grape growing moved to the Central Valley.

In 1981 Johnson organized landowners and county officials who toured the Mother Lode wine country and learned its soils and climate are similar to those of Mariposa County.

Later, he and other UC experts guided development of new plantings in the county, which today has about a dozen vineyards, several with on-farm wineries and tasting rooms catering to tourism.