Description of the Disease
Red thread may kill turfgrass in patches that are 2 to 8 inches in diameter, or the disease may occur over large areas without killing the plants. A pink web of fungal threads binds the leaves together. Look for pink, gelatinous fungal crusts projecting from the leaves to help identify this disease.
Susceptible Turfgrasses
Bentgrasses, bluegrasses, fescues, ryegrasses, and bermudagrasses are susceptible to red thread.
Conditions Favoring Disease
This disease occurs most frequently along the coast of northern and central California but may be found in southern California on rare occasions. The disease is common under conditions of mild air temperatures (60° to 75°F) and extended periods of leaf wetness. It often appears on plants deficient in nitrogen during periods of cool or warm temperatures if there is adequate moisture (excess irrigation or rainfall).
Management
Providing proper irrigation and fertilization can reduce the incidence of red thread. Adequate nitrogen can usually prevent this disease from occurring. Prevent drought stress by irrigating turfgrass based on evapotranspiration needs of the turfgrass. Provide adequate air circulation and reduce shading. Fungicides are rarely warranted except in severe cases.
| Common name | Amount to use | Ag Use REI‡ |
NonAg Use REI‡ |
|
|---|---|---|---|---|
| (Example trade name) | (hours) | (hours) | ||
| Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide's properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. | ||||
| A. | AZOXYSTROBIN | |||
| (Heritage) | 0.2–0.4 oz/1000 sq ft | 4 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) | ||||
| B. | CHLOROTHALONIL | |||
| (Daconil Action) | Label rates | 12 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M5) | ||||
| C. | FLUTOLANIL | |||
| (Prostar WG) | Label rates | 12 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Carboxamide (7) | ||||
| D. | IPRODIONE | |||
| (Chipco 26019) | 4 fl oz/1000 sq ft | See label | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Dicarboximide (2) | ||||
| E. | MANCOZEB | |||
| (Fore 80WP, Dithane M-45) | 4–8 oz/1000 sq ft | 24 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M3) | ||||
| COMMENTS: Dithane M-45 registered for use on sod farms only. | ||||
| F. | MYCLOBUTANIL | |||
| (Eagle 20EW) | 1.2 fl oz/1000 sq ft | 24 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) | ||||
| G. | PROPICONAZOLE | |||
| (Banner Maxx) | 2 fl oz/1000 sq ft | 12 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) | ||||
| H. | THIOPHANATE-METHYL | |||
| (Fungo Flo) | Label rates | 12 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) | ||||
| I. | TRIADIMEFON | |||
| (Bayleton 50 Turf and Ornamental) | Label rates | 12 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) | ||||
| J. | TRIFLOXYSTROBIN | |||
| (Compass) | Label rates | 12 | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) | ||||
| K. | VINCLOZOLIN | |||
| (Curalan EG, Touche EG) | 2.7 lb/acre (1 oz/1000 sq ft) | 120 (5 days) | Until dry | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Dicarboximide (2) | ||||
| 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. |
| ‡ | Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Agricultural use applies to sod farms and commercial seed production. |