University of Vermont Extension
System
Department of Plant and Soil Science
Powdery Mildew on Phlox and Monarda:
COH 40
Control Studies, References
Dr. Leonard P. Perry, Extension Professor
Organic Controls Research (Vermont)
1991-93 in Vermont, 'White Admiral' Phlox, replicated
-
Best control (no differences among treatments):
4 Baking soda, 0.5% (1.5Tbsp/gal
water, weekly)
4 Sunspray Horticultural Oil (3Tbsp/gal
water, every 2 weeks)
4 Both combined (every 2 weeks)
-
Least control (worst treatments, not effective):
t Antidessicants (Wilt-Pruf, ForEverGreen)
t Mulch, 2" (bark, marble chips)
t Spacing (1 or 2 ft)
-
Horticultural oil is only one registered for use as a fungicide
-
Worst treatments in this study often provide some control in less stressful
situations, in landscapes, or for individual plants
-
Antidessicants form a barrier, preventing diseases from entering the leaf;
so as leaves grow they must be reapplied to remain effective (not done
in above studies)
1999, ‘Mr. Fuji’ Phlox, replicated
-
Best control (no differences among treatments):
4 WiltPruf, followed by Remedy
-
Least control (worst treatments, not effective):
t Neem
-
Moderate control from horticultural oil (Sunspray Ultrafine) or baking
soda
2000-2001, ‘Snow White’ Bee Balm (Monarda didyma)
-
Best control (no differences among treatments):
4 WiltPruf and SunSpray in 2000,
Sunspray and Remedy (potassium bicarbonate) in 2001
-
Least control (worst treatments, not effective):
t Neem in 2000 (not used in 2001), Sulfur
(not used in 2000) and baking soda in 2001
-
In 2000, Remedy and baking soda became less effective over time
-
In 2001, WiltPruf was effective at first but less so over time
Chemical Controls Research
-
Long Island (Margery Daughtrey)
-
1990, 4 phlox cultivars, horticultural oil at both 2 and 4 week intervals
provided as good or better control than Bayleton
-
1991-92, replicated for phlox and monarda cultivars:
3 Significant control by horticultural
oil at 2% and 3% rates, and at 2 and 3 week intervals
3 Often Funginex provided the least
control
3 Bayleton control was intermediate
Some Useful References
-
Pest Management Recommendations for Production of Herbaceous Perennials,
Cornell University
-
Perry's Perennial Pages: http://www.uvm.edu/~pass/perry/
-
Smith, Michael. The Ortho Problem Solver.
-
Pirone, Pascal. Diseases and Pests of Ornamental Plants.
-
Olkowski, W., S Daar and H. Olkowski. The Gardener’s Guide to Common
Sense Pest Control. Timber Press, 1995.
-
Chase, Daughtrey and Simone. Diseases of Annuals and Perennials. Ball
Publ. 1995.
-
C. Powell and R. Lindquist. Ball Pest and Disease Manual, 2nd ed. Ball
Publ. 1997.
-
Gill, Clement and Dutkey. Pests and Diseases of Herbaceous Perennials.
Ball Publ. 1999
-
Perry, Leonard. Herbaceous Perennial Production. NRAES, Riley Robb
Hall, Cornell Univ., Ithaca NY 14853
-
New England Greenhouse Floricultural Recommendations, A Management Guide
for Insects, Diseases, Weeds and Growth Regulators. 2001-2002. Bulletin
Center, Draper Hall, Univ. Mass., Amherst, MA 01003
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