The low-chill, southern highbush group of blueberries are the varieties that offer the most promise for extended season production on the central California coast. Some of these varieties require little or no chilling to break dormancy and stay green year-round if temperatures are mild. Flowering and fruiting is a function of pruning and other cultural practices and temperature during the fruiting period. Even though the plants flower and fruit throughout the late fall and winter months, often there is not adequate heat to ripen the fruit normally. However, I have observed blueberry fruiting and ripening into the late fall (November) and depending on the area, early spring production is also possible. Additional special cultural practices related to soil management are also important for successful blueberry production.

Some initial data is now available illustrating the production potential for several southern highbush blueberry varieties. This trial was established initially because of uncertainty over which of this group of low-chill blueberry varieties offers the greatest potential for production in mild coastal growing areas. I am also interested in the production cycles of these varieties and how different varieties might fit into a production program in different growing areas.

These plants were established in coastal San Luis Obispo County in mid-1997 from 18 month-old plants. Flowers and fruit were stripped from the plants until the 1999 season when a light harvest was taken. The data summarized below is from March through June 2000.

The production data for six southern highbush-type blueberry varieties is summarized in Figures 1-3 on pages 3-4. The varieties harvested thus far include Sharpblue, Georgia Gem, Marimba, Misty, Gulf Coast, and Cape Fear.

Sharpblue is a widely grown, early-season variety, and Sharpblue started producing earliest in this trial. The surprise, however, is that Sharpblue maintained a production edge over the other varieties throughout the harvest season (Figs. 1, 2). The Sharpblue produced highest per plant marketable yields (Fig. 1), and highest number of marketable fruit per plant (Fig. 2) over most of the harvest season. Mean fruit size was highest with Sharpblue early in the season, but fell off mid-way through the season (Fig. 3).

Other varieties such as Marimba, Georgia Gem, and Gulf Coast also have shown good overall plant vigor and were productive in this initial harvest. Gulf Coast has been reported to have problems on picking because the fruit does not break free from the stem easily, and the stem may stay with the fruit. This was true in this trial and may increase harvest costs for some market situations. And this trait may limit the suitability of Gulf Coast in commercial fields. Misty can be quite variable in overall plant vigor, and this is reflected in Misty’s relatively low yields in this trial. Reports from the University of Florida indicate that Misty has a tendency to over-produce flowers and fruit on young plants, and vegetative development is restricted if plants are not pruned aggressively.

Another marked advantage of mild, coastal growing conditions is the relatively long harvest period, which in this trial lasted up to 12-14 weeks. Warmer production areas typically produce berries over a shorter harvest season lasting 3-6 weeks. The total cumulative yield of Sharpblue during the harvest period exceeded 6.5 lb per plant, and yields should continue to increase over the next 4-6 harvest seasons.

Newer varieties have been bred with reportedly improved fruit quality characteristics over that of Sharpblue. To date we have limited data available showing production potential of different blueberry varieties under coastal California growing conditions. Sharpblue fruit is attractive and flavorful and readily accepted in the marketplace. Sharpblue is widely adapted and vigorous and should be one of the key varieties to be included in new plantings until information is available which clearly shows advantages for the newer varieties.

A 3-day conference entitled "Markets, Tools, and Opportunities for Limited Resource Farmers" - An Agricultural Marketing Outreach Conference is planned for Modesto, CA, at the Doubletree Hotel and Modesto Centre Plaza October 31-November 2, 2000.

The conference, sponsored by the USDA, the College of Agriculture at CalPoly, San Luis Obispo, and the UC Small Farm Center. Conference topics included sessions on wholesale marketing, contract marketing, food quality and safety, PACA rights, marketing cooperatives, export markets and federal procurement programs.

Additional topics include new products, agrotourism, value-added products, direct consumer marketing, and farm management/record keeping. A day of tours to small-scale farming and processing operations in the northern San Joaquin Valley is also planned. The $150 registration fee includes admission to all events including two lunches, two dinners, and workshops. For more information contact the College of Agriculture at CalPoly at 1-888-277-5624 or e-mail to cagr@calpoly.edu