By: Erin Norton, Ph.D.
This year, as a collaborative project, Randall Vos and the MGWII are conducting a berry maturity study across the state of Iowa and into Illinois. Several vineyards are sending weekly samples of grapes to the MGWII labs at Iowa State University where they are being analyzed for maturity standards (°Brix, pH, TA, berry weight). Results are being released at the end of each week throughout the harvest season.
The goal is to give all growers an idea of the degree of ripening happening in their area and other areas. All growers are still encouraged to sample their own vineyards. It is important to take a representative sampling from each plot (for each cultivar) to get an overall idea of the ripeness of that cultivar. While many growers rely on soluble solids measurement ((°Brix) to make harvest decision, we highly recommend checking acidity (pH and TA) as well. Tasting the fruit/juice is another important measurement to perform, and observation of the seed ripeness.
To get started with a sampling program, please see the Fact Sheet series on Grape Maturity (FS49) at the ISU Extension Store.
We would like to expand the project next year to include growers distributed around the state.