Article written by Madeline Wimmer, Extension Educator - Fruit Production Grapes: Growth stage update: Nearing harvest Article topic: Measuring fruit ripeness Nutrition: Magnesium deficiency Blueberries: Nutrition: Iron deficiency Plums: Mount Royal (European plum) at harvest Grapes Growth stage update: Nearing harvest Images: Itasca and Marquette, two UMN grape cultivars, along with Sabrevois, Swenson White, and Louise Swenson, cultivars bred by Elmer Swenson. Photos taken at Salem Glen Winery, located in Olmsted County (Zone 5a). This week I stopped by Salem Glen Winery to check on their wine grape development. Salem Glen has been growing a wide variety of grapes since the early aughts, including a number of French-hybrid grapes (e.g. Foch), UMN bred grapes, as well as cultivars bred by Elmer Swenson and Tom Plocher (e.g. Petite Pearl, Crimson Pearl). Many of these cultivars were measuring around 14 ° Brix out in the field, ...
Madeline Wimmer, Extension Educator and Soon Li Teh, Extension Specialist Grapes are a fruit crop with distinct, measurable ways to determine fruit ripeness. Harvested too early, and the fruit will be unbalanced with higher acidity and lower sugar levels. Using taste and visual cues can be informative for fresh grapes, but sweetness can often mask acidity and be deceptive. With knowledge of the fruit development process and by using the right tools and methods to track berry ripening, a vineyard can be confident in its ability to harvest a quality crop. Information in this article: Grape berry ripening phases How to sample berries Analyzing juice for sugar levels, pH, and titratable acidity Additional ripeness indicators Grape berry ripening phases Grape berries generally go through three developmental stages for ripening: Stage I : This is the earliest phase that happens right after fruit set. Cells within the berry begin to divide and multiply, which leads to a...