The threecornered alfalfa hopper (TCAH) is a vector of Grapevine red blotch virus that causes Grapevine red blotch disease in vineyards. A degree day model was developed to predict the ideal time frame for ground cover management to help reduce TCAH populations in vineyards.
The following video below walks through the steps on how to use the UCIPM website to calculate degree days for your specific vineyard and then use the model to time ground cover management for reduction of TCAH in your vineyard.