Envirologix: Putting Science to the Test

Measure the Primary Cause of Bunch Rot with a New, Rapid Test

The EnviroLogix QuickStix Kit for Botrytis in wine grape juice is the first rapid test to detect and quantify the primary cause of bunch rot. Used with a QuickStix Reader, the test provides semi-quantitative analysis of Botrytis cinerea—enabling vineyards, laboratories and wineries to make better decisions on harvesting, segregation and processing.

Botrytis is one of the wine grape industry’s main diseases. It has been described as the industry’s “billion-dollar challenge,” owing to the associated costs of management, lower-quality berries and lost sales.

An immunoassay, the QuickStix test works on the immunological principle that specific antigens will stimulate very unique immune responses. The proteins produced by the immune response, called antibodies, can be used to signal the presence of a target compound in a sample. Providing rapid, sensitive and affordable screening of a variety of compounds, the method has been widely used in the medical, veterinary and horticultural industries for many years.

The test kit uses a Botrytis monoclonal antibody that recognizes a specific Botrytis antigen in grape juice from infected berries. In its lateral flow (or immunostrip) format, the device has been used by researchers in California and New Zealand to detect and quantify the Botrytis fungus in juice from immature and harvested berries.

Frances M. Dewey, Ph.D., of the University of Oxford, England, created the measurement scale employed by the QuickStix testing system. The Dewey I-W Standard, developed during her work with the California Wine Grape Inspection Advisory Board, measures Botrytis levels on the basis of incidence or weight.

The scale is derived from combining 20 half-turgid Botrytis-infected berries with 80 uninfected berries, giving a 20 percent incidence standard. This juice is then diluted further into juice from uninfected berries to achieve a measurement range. Percent by weight is obtained by multiplying the incidence level by 0.333, as a half-turgid Botrytis-infected berry weighs, on average, one-third that of an uninfected berry.

The ability of the QuickStix system to determine whether Botrytis is present, and to what degree, allows growers and vintners alike to make critical decisions prior to crushing the fruit, so that the juice can be managed to best meet the winery's needs.

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