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How to Manage Pests
UC Pest Management Guidelines
Turfgrass
Melting Out
Pathogen: Drechslera poae
(Reviewed 6/03,
updated 6/03)
In this Guideline:
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DESCRIPTION OF THE DISEASE
Melting out causes circular to elongated purplish or brown spots with
straw-colored centers on leaf blades, leaf sheaths, and stems. The leaf spots
may be widespread throughout the lawn, indicating spread by windborne spores.
Crowns and roots are frequently affected with a dark brown rot. The
crown-infected plants are weakened and may die in hot, windy weather, resulting
in a thinning out of the turf in scattered areas. The fungus survives on
infected bluegrass plants or grass debris and may be seedborne.
SUSCEPTIBLE TURFGRASSES
Kentucky bluegrass is highly susceptible to melting out. Many improved
bluegrass selections are resistant, including: Adelphi, Bristol, Destiny,
Eclipse, Enmundi, Glade, Ikone, Liberty, Majestic, Mona, P-104, Rugby, and
Somerset.
CONDITIONS FAVORING DISEASE
Cool (50° to 75°F), moist conditions favor melting out. Symptoms
first appear on shaded plants. Melting out is most severe on closely mowed turf
and on turf with high nitrogen fertilization.
MANAGEMENT
To prevent the development of melting out, follow good management practices.
Reduce shade, improve soil aeration and water drainage, and control thatch.
Avoid dry spots and maintain as high a cutting height as feasible. Apply
recommended rates of nitrogen fertilizers. Select resistant cultivars. With the
use of resistant cultivars and other recommended cultural management practices,
fungicides should not be necessary in most situations. For susceptible
cultivars, treat at the onset of symptoms.
| 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 |
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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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