Stuck, or sluggish, grape juice fermentations are a recurring problem in the wine industry. Defined as those that take longer than two weeks to finish ,or those that stop prematurely with a residual sugar concentration of greater than 0.2%, stuck fermentations can severely delay the fermentation schedule in a commercial winery. This needlessly extends harvest and dominates tank space.
Nitrogen levels in grape must that are either too high or too low can cause sensory and economic issues in the production of fine wine. The amount of available nitrogen during fermentation is key to the healthy formation and reproduction of yeast, and completion of the process to dryness. The major yeast strain that dominates healthy alcoholic fermentation, Saccharomyces cerevisiae, typically produces one molecule of urea, glutamate, and proline from the metabolism of the amino arginine.
Developing Pinot noir crop load metrics that are adaptable to Winery site and wine quality production goals II-grape and wine quality evaluation abstract In the Pacific Northwest wine grapes are…
Blueberry shock virus (BlShV) is a serious problem in blueberry production in the Pacific Northwest (PNW) region of North America. Infection occurs during bloom and the virus moves into other parts of the plant in an uneven but steady manner and may take several years to become fully systemic in mature bushes. In the year after infection, emerging flower and leaf tissues die rapidly at full bloom followed by regrowth. Once symptoms have been exhibited in all parts of the plant, the plant remains asymptomatic in subsequent years. Infection in young plants of some cultivars can stunt the plant for the remainder of its life, however, more typically production is lost for one year. While there appears to be no immunity as tested by grafting, it has been recognized that the rate of infection varies among genotypes. Plants in the HCRU breeding program and at the NCGR, have been tested regularly by ELISA for BlShV, in some cases for nearly 20 years, and germplasm that is particularly slow to become infected has been identified. At Oregon State University, North Willamette Research and Extension Center (NWREC), ‘Legacy’ , ‘Toro’, ‘Bluecrop’, ‘Baby Blues’, ‘Darrow’ and all rabbiteye cultivars have tested negative for BlShV for over 10 years while growing among many known positive plants. On the other extreme, ‘Berkeley’, ‘Bluegold’, ‘Brigitta Blue’, ‘Nui’ and ‘Spartan’ tested positive in the year following their 1st bloom. At the NCGR, ‘Bladen’, ‘Harding’, ‘Lateblue’, ‘Legacy’, ‘Razz’, US 612, US 693, US 845, and US 847 all tested negative after 20 years in the field. ‘Toro’ and ‘Bluecrop’, which had tested negative after 20+ years at NWREC, were positive at the NCGR, as were many Rabbiteye cultivars. Crosses will have been made among genotypes that are slow to test positive for BlShV to try to develop this trait in cultivars.
Developing commercial blueberry cultivars adapted to the Pacific Northwest and that may tolerate Blueberry shock virus and testing new selections and cultivars from other programs abstract Blueberry shock virus (BlShV)…
