DESJARDINS GROUP LOWERS VISA INTEREST RATE (La Confederation des Caisses Populaires et d'Economie Desjardins), the Quebec credit union group, said it is lowering the interest rate on unpaid balances on its Visa credit card to 15.9 pct from 18.0 pct, effective with June billing statements. The move follows cuts in credit card interest rate charges by several Canadian banks.