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UC Pest Management Guidelines

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Turfgrass

General Properties And Use Of Fungicides

(Reviewed 9/09, updated 9/09)

In this Guideline:

The fungicide products mentioned in this section are registered for use on turfgrass in California, but many have not been evaluated by the University of California for their effectiveness in controlling turfgrass diseases. The fungicides are listed alphabetically in the treatment tables and not necessarily in the order of effectiveness. In general, use fungicides only on golf and bowling greens and other high maintenance turfgrasses. For best results, use fungicides preventively based on history of previous diseases and when conditions are conducive to disease development or when the disease is first visible. Accurate identification of a disease is critical to choosing the best fungicide. Read and follow fungicide label recommendations carefully for rate recommendations, which usually vary based on the severity of the disease and whether the treatment is preventive or curative.

Turfgrass areas such as landscape areas and parks only rarely require fungicide applications. Good cultural practices including proper turf species selection, appropriate use of fertilizer and irrigation will prevent serious damage in most turfgrass areas.

To help prevent the development of resistance to a pesticide, rotate pesticides with different mode-of-action Group numbers. These numbers are listed with each pesticide in the treatment tables throughout this guideline.

Common name
(example trade names)		 Chemical class Activity Mode of action
(FRAC Group No.1)		 Resistance potential Comments
azoxystrobin (Heritage) QoI2 systemic single-site (11) high4  
captan (Captan) phthalimide contact multi-site (M4) low highly toxic to bees
chlorothalonil (Concorde, Daconil) chloronitrile contact multi-site (M5) low  
fenarimol (Patchwork, Rubigan) DMI3-pyrimidine systemic6 single-site (3) high  
fosetyl-al (Aliette, Prodigy, Chipco Signature) phosphonate systemic multi-site (33) low  
fludioxonil (Medallion) phenylpyrrole contact few to multi-site (12) medium  
flutolanil (Prostar) carboxamide — multi-site (7) medium  
iprodione (Chipco 26019) dicarboximide systemic multi-site (2) low  
mancozeb (Fore, Dithane M-45, Manhandle) carbamate (EBDC)5 contact multi-site (M3) low  
mefenoxam (Subdue Maxx, Apron) phenylamide systemic single-site (4) high4  
myclobutanil (Eagle) DMI3-triazole systemic6 single-site (3) high  
PCNB (Engage, Revere, Terrachlor, Turfcide) aromatic hydrocarbon slight systemic single-site (14) medium  
propiconazole (Banner Maxx) DMI3-triazole systemic6 single-site (3) high  
sulfur inorganic contact multi-site (M2) low  
thiophanate-methyl (Cavalier, Fungo 50, T-Methyl E-Pro) benzimidazole systemic single-site (1) high  
triadimefon (Accost, Bayleton) DMI3-triazole systemic6 single-site (3) high  
trifloxystrobin (Compass) QoI2 systemic6 single-site (11) high4  
vinclozolin (Curalan, Touche) dicarboximide systemic (local) multi-site (2) low  
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action Group number.
2 Qol = quinone outside inhibitors
3 DMI = demethylation inhibitors
4 Resistance has been found in California for certain fungicides with a single-site mode of action. To reduce the risk of resistance development, take the mode of action into account when choosing a fungicide. At the beginning of a treatment program, use a fungicide with a multi-site mode of action; for subsequent applications rotate or mix fungicides with different mode of action FRAC numbers. Use labeled rates (preferably the upper range) of the single-site fungicides, and limit the total number of applications/season.
5 EBDC = ethylene bisdithiocarbamate
6 Generally considered to have systemic action based on performance data but has not been proven experimentally.

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
General Information
M. L. Flint, UC IPM Program, UC Davis
M. A. Harivandi, UC Cooperative Extension, Alameda County
H. K. Kaya, Nematology, UC Davis

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