This is academic to me as we don't see native or hybrid US wines here in UK (except sometime NY Kosher wine), but there's an interesting article in the Fall 2019 American Wine Society Journal that says foxy tastes vanish when the grapes are fully ripe.
The article, by Jim Rink, tells that this is the theory of Nathaniel Rose of Nathaniel Rose Wines, MI who made wines from late harvested hybrids when his expected delivery of vinifera didn't arrive
In short, it says,
1) foxiness is caused by methyl anthranilate
2) methyl anthranilate levels rise in hybrid grapes as they ripen
3) when grapes are fully - physiologically - ripe, methyl anthranilate levels disappear
4) methyl anthranilate is sprayed on crops by farmers as a bird deterrent, as birds hate its taste
5) vines want their grapes to be eaten so seeds are dispersed, (thus they change colour when ripe)
6) vines don't want unripe grapes to be eaten as unripe seeds won't germinate
7) thus evolution has given native wines methyl anthranilate as a bird deterrent until grapes are fully ripe
8 ) because hybrids quickly produce high sugar and low acidity before physiological ripeness they usually are harvested with methyl anthranilate - thus foxiness
Calling Paul Bulas !!
