Why Is My Wisteria Yellow. Irregular dark brown marks and blotches usually with a yellow margin are a symptom of infection by the fungal disease powdery mildew. Asked by Anonymous on May 9 2011.
Jun 21 2020 It could be powdery mildew which actually doesnt show the usual white powder on wisteria - according to the RHS who advise you make sure your wisteria is well ventilated so air can circulate and try overhead watering mid morning to wash it off. Discoloring is extremely noticeable on the Chinese wisteria Wisteria sinensis due to the plants purplish leaves. Sep 06 2011 Member.
Article byGardening Know How 24.
Sep 06 2011 Member. Aphid infestation is the reason why Wisteria leaves get curled and turn yellow in color. Leaves will first turn yellow and if untreated may turn brown. We have had plenty of rain this year and temps are 50 at night to 80 in the daytime.