University of Vermont Extension System
Department of Plant and Soil Science

Powdery Mildew on Phlox and Monarda:                                 COH 39
Overview, Cultivar Resistance

Dr. Leonard P. Perry, Extension Professor



The Problem

Cause Conditions affecting mildew Management Options

Phlox Cultivar Resistance

4 David (white)

4 Orange Perfection (dark salmon)

4 Prime Minister (white, red eye)

4 Starfire (red)

Monarda Cultivar Resistance

NC State Univ. cultivar ratings (Dick Bir, Fletcher NC MHCREC), replicated 1998
Least disease—early season (early June) Least disease—late season (late July)
Claire Grace

Marshall’s Delight

Stone’s Throw Pink

Beauty of Cobham

Blue Stocking

Cambridge Scarlet

Elsie’s Lavender


Marshall’s Delight

Vintage Wine

Severe disease pressures at this location, with much rain and fog. At least 45% defoliation on all early in season, and at least 65% defoliation on all late in season.

Chicago Botanic Garden cultivar ratings (Richard Hawke), replicated 1993-1996 (more common shown)
Least or no disease High disease
Colrain Red

Gardenview Scarlet

Marshall’s Delight

Ohio Glow

Petite Delight

Raspberry Wine


Violet Queen


Beauty of Cobham

Cambridge Scarlet

Croftway Pink


Mrs. Perry


Prairie Fire

Snow Queen


fistulosa ‘Claire Grace’

Vermont cultivar ratings, replicated 1994-1997 (Leonard Perry et al)
Least or no disease High disease
Blue Stocking (purple)

Marshall's Delight (pink)

Violet Queen (purple)

Adam (red)

Cambridge Scarlet (red)

Croftway Pink (pink)

Souris (pink)

Vermont cultivar ratings, replicated 1999- present

Promising for least disease: Jacob Cline, Petite Delight, Petite Wonder COH39 11/15/01

Return to Perry's Perennial Pages

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. Lawrence Forcier, Director, UVM Extension System, Burlington, Vermont. University of Vermont Extension System and U.S. Department of Agriculture cooperating, offer education and employment to everyone, without regard to race, color, national origin, sex, religion, age, disability, political beliefs, and marital or familial status.

Last reviewed 11/15/01