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 these guidelines.
| Common name (Example trade name) |
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 | |
| 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) | 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 (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 (Fungo Flo) | benzimidazole | systemic | single-site (1) | high | |
| triadimefon (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 action. 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 a 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 per season. |
| 5 | EBDC = ethylene bisdithiocarbamate |
| 6 | Generally considered to have systemic action based on performance data but has not been proven experimentally. |