purple blotch

purple blotch

[′pər·pəl ¦bläch]
(plant pathology)
A fungus disease of onions, garlic, and shallots caused by Alternaria porri and characterized by small white spots which become large purplish blotches.
References in periodicals archive ?
If this ink were to leak in your field vest it would go through many layers of clothes and leave a purple blotch on your skin that will not wash off for a month or more.
There are reliable bulbs and corms for summer, too ( old favourites like lilies and newly fashionable Acidanthera murielae (pictured), bearing numerous pure white blooms with a purple blotch in the throat.
Pointing to a purple blotch, where he has a cabin with a Grassy Narrows trapper, Billard says, "If they cut here, we'll have to pretend we're living in a forest.