Diagnosing Utricularia longifolia Discoloration: Powdery Mildew

A South Florida grower's indoor U. longifolia (75°F, east window, pure sphagnum, pure water, no fertilizer) turns purplish from base up, losing leaves rapidly. Photo shows affected plant.

Jeff Dallas suspects powdery mildew—common on U. longifolia. Advises removing affected leaves and daily misting to prevent spore adhesion. Fungicides are problematic: Utricularia are sensitive, and waxy leaves reduce treatment efficacy.

Follow-up: Grower notes discoloration is inside leaves, no external powder. Dallas clarifies powdery mildew appears as fine white powder (often subtle) and causes internal discoloration. Overhead watering/misting keeps spores off new growth. Treatment remains cultural.

Powdery mildew thrives in stagnant, humid air. Air circulation, misting, and prompt removal of infected tissue are primary controls for this sensitive genus.