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How to Manage Pests
UC Pest Management Guidelines
Turfgrass
Red Thread
Pathogen: Laetisaria fuciformis
(Reviewed 6/03,
updated 6/03)
In this Guideline:
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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 |
Chemical class |
Many of these products are available for use by licensed applicators only and cannot be used by home gardeners.
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| A. |
AZOXYSTROBIN |
QoI (strobilurins) |
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| B. |
CHLOROTHALONIL |
Chlorophenyl (multi-site) |
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| C. |
FENARIMOL |
DMI |
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| D. |
FLUTOLANIL |
Oxathiin |
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| E. |
IPRODIONE |
Dicarboximide |
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| F. |
MANCOZEB |
EDBC (multi-site) |
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| G. |
MYCLOBUTANIL |
DMI |
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| H. |
PROPICONAZOLE |
DMI |
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| I. |
THIOPHANATE-METHYL |
Benzimidazole |
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| J. |
TRIADIMEFON |
DMI |
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| K. |
TRIFLOXYSTROBIN |
QoI (strobilurins) |
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| L. |
VINCLOZOLIN |
Dicarboximide |
UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
Diseases
F. Wong, Plant Pathology, UC Riverside
M. A. Harivandi, UC Cooperative Extension, Alameda Co.
J. Hartin, UC Cooperative Extension, San Bernardino Co.
Acknowledgment for contributions to the disease section:
M. E. Grebus, Plant Pathology, UC Davis
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