It seems that setting DateFormat doesn't have any effect. It alwys tend to format like this '06/24/2016'.
Code:x.DatePickerField()
.Label("Date")
.DestroyPickerOnHide(true)
.Name("date")
.DateFormat("d-m-Y")
.Picker(
x.DatePicker()
.YearFrom(1990)
.DateValue(new DateTime(2016, 6, 24))
)
)