How to Manage Pests

UC Pest Management Guidelines

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		Example trade names	Ag Use R.E.I.+	NonAg Use R.E.I.+
(trade name)			(hours)	(hours)
When choosing a fungicide, consider general properties as well as information relating to environmental impact.
A.	AZOXYSTROBIN	Heritage
	MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11)		4	until dry
B.	CAPTAN	Captan
	MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M4)		4 days	until dry
C.	CHLOROTHALONIL	Daconil
	MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M5)		12	until dry
D.	FLUDIOXONIL	Medallion
	MODE OF ACTION GROUP NAME (NUMBER1): Phenylpyrrole (12)		12	until dry
E.	IPRODIONE	Chipco 26019
	MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2)		see label	until dry
F.	MANCOZEB	Fore, Dithane M-45
	MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M3)		24	until dry
	COMMENTS: Dithane M-45 registered for use on sod farms only.
G.	MYCLOBUTANIL	Eagle
	MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)		24	until dry
H.	PROPICONAZOLE	Banner Maxx
	MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)		24	until dry
I.	THIOPHANATE-METHYL	Fungo 50, T-Methyl E-Pro
	MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1)		12	until dry
J.	TRIFLOXYSTROBIN	Compass
	MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11)		12	until dry
K.	VINCLOZOLIN	Curalan, Touche
	MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2)		5 days	until dry
1	Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). 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 fungicide with a different mode of action Group number.
+	Restricted entry interval (R.E.I.) 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.

PUBLICATION

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 County
Acknowledgment for contributions to Diseases:
J. Hartin, UC Cooperative Extension, San Bernardino County
M. E. Grebus, Plant Pathology, UC Riverside

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