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How to Manage Pests
UC Pest Management Guidelines
Turfgrass
Leaf Blotch
Pathogen: Bipolaris cynodontis
(Reviewed 6/03,
updated 6/03)
In this Guideline:
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DESCRIPTION OF THE DISEASE
Leaf blotch appears as tiny purplish to reddish spots that occur on leaf blades
and leaf sheaths. Seedlings are very susceptible, but older plants rapidly
become resistant. Affected seedlings wither, die, and turn brown. The roots and
crowns of infected plants may develop small lesions and rot. The disease occurs
in irregular patches that range in size from 2 inches to 3 feet across.
SUSCEPTIBLE TURFGRASSES
Leaf blotch is a disease of bermudagrass. The pathogen survives in infected
bermudagrass plants and debris.
CONDITIONS FAVORING DISEASE
Leaf blotch damages young bermudagrass seedlings or adult plants that are
weakened by factors such as excess thatch, nitrogen deficiency, and other
unfavorable growing conditions. The disease attacks during cool, wet weather,
with symptoms usually seen from late autumn to spring.
MANAGEMENT
Follow good management practices; fungicides are usually not necessary except
in young turfgrass.
Cultural Control
Remove thatch at regular intervals and apply adequate nitrogen to help prevent
the development of this disease. Manage leaf wetness by irrigating pre-dawn to
early morning.
Treatment Decisions
Fungicides are primarily used in young turfgrass; established, healthy
turfgrass is not usually damaged by this disease.
| 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. |
CAPTAN |
Pthalamide (multi-site) |
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| C. |
CHLOROTHALONIL |
Chlorophenyl (multi-site) |
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| D. |
FLUDIOXONIL |
Phenylpyrrole |
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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. |
TRIFLOXYSTROBIN |
QoI (strobilurins) |
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| K. |
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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