Pepper stip is a physiological disorder manifested as gray-brown to greenish spots occurring on fruit of bell, pimento, Anaheim, and other types of peppers, most noticeably on red fruit produced under fall conditions. The spots, ≈0.5 cm in diameter, occur singly or in groups; marketability for either fresh market or processing use is severely affected. The factors controlling the occurrence or severity of the disorder are not well understood; to date, control has been achieved primarily by the use of resistant cultivars. In 1995 replicated plots of susceptible (`Yolo Wonder L' and `Grande Rio') and resistant (`Galaxy' and `King Arthur') cultivars were grown in seven commercial fields in central California. `Galaxy' and `King Arthur' were essentially free of symptoms, while `Yolo Wonder L' and `Grande Rio' showed significant damage at all sites, with 23% to 88% of fruits affected at the mature-red stage. Petiole tissue analysis showed that resistant cultivars consistently had lower N and K, and higher Ca concentrations than susceptible cultivars; the same trend was apparent in fruit tissue. Stip was most severe at sites with low soil Ca and/or very high N and K fertilization rates. It is hypothesized that Ca nutrition significantly influences stip expression.
Richard Smith, Bob Mullen, and Tim Hartz
Mike Murray, Mike Cahn, Janet Caprile, Don May, Gene Miyao, Bob Mullen, Jesus Valencia, and Bill Weir
University of California Cooperative Extension farm advisors have conducted applied research to quantify processing tomato [Lycopersicum esculentum (L.) Mill] varietal performance, as a coordinated activity, since 1973. Early and midseason maturity varieties are annually evaluated at four to six locations throughout the state. The test varieties are selected in collaboration with seed companies, processors and growers. The growers and seed companies provide financial support for the tests. Most tests are conducted in production tomato fields and are harvested using commercial harvesters. The results are widely disseminated through an annual report to the funding sources, farm advisor research reports, newsletters, production meetings, the California Tomato Grower magazine, and popular media. The information obtained for fruit yield potential, fruit quality and plant horticultural characteristics is used by processors, growers, and seed companies to make variety selection decisions. This regional extension program has proven to be an effective way to generate well-designed replicated information for making intelligent processing tomato cultivar decisions and has been well accepted by the California industry.