Diseases ›

Large Patch

Symptoms

Large patch is a new name for an old disease of warm-season turfgrasses. This disease was formerly called brown patch, the same disease that affects cool-season grasses during hot weather. Other than the fact that they affect different grasses, there are several important differences between brown patch and large patch that necessitated a name change: they occur at different times of the year, produce distinct symptoms, are caused by different strains of the fungus Rhizoctonia solani, and require very different control strategies.

Development Factors

Large patch begins to develop when soil temperatures decline to 70°F in the fall, but the symptoms do not necessarily appear at this time. The symptoms of large patch are most evident during periods of cool, wet weather in the fall and spring. In many cases, symptoms may not become evident until early spring when the warm season grasses are greening up.

Large patch is favored by excessive nitrogen in the fall and spring, poor soil drainage, over-irrigation, excessive thatch accumulations, and low mowing heights. Centipedegrass and seashore paspalum are most susceptible to large patch, followed by zoysiagrass, and then St. Augustinegrass. Bermudagrass, rarely affected by large patch, recovers very quickly when the disease does occur.

Cultural Control

Establishment of a disease-resistant turfgrass species is the most effective means for management of large patch. Bermudagrass rarely sustains significant damage from large patch, and grows of out the symptoms quickly when the disease does occur. In contrast, centipedegrass, seashore paspalum, St. Augustinegrass, and zoysiagrass often sustain serious damage and recovery can take several weeks or months. Fescues and bluegrasses are immune to large patch and are also an option in areas where cool-season turfgrasses can be maintained.

Do not apply nitrogen to warm-season grasses in the fall and spring. These grasses are growing slowly during this time and do not require a significant amount of this nutrient. In general, nitrogen should not be applied to the warm-season grasses within 6 weeks before dormancy in the fall or within 3 weeks after green-up begins in the spring. Warm-season grasses vary in their fertility requirements, so refer to local university recommendations for more specific recommendations for timing and rates.

Avoid establishing warm-season grasses in low lying areas that remain saturated for extended periods of time from surface runoff. If this is unavoidable, install subsurface drainage to remove excess water from the soil. Irrigate only as needed to prevent severe drought stress in the fall and spring. Control traffic patterns to prevent severe compaction, and aerify as needed to maintain soil drainage and aeration. Mow at recommended heights, and power rake or vertical mow as needed to control thatch accumulations.

Chemical Control

Fungicides are available for large patch control, but must be applied on a preventative basis. Applications should be initiated in the fall when soil temperatures decline to 70°F for 5 or more consecutive days, regardless of when symptoms have appeared in the past. One or two well-timed applications provide season-long control of large patch in many situations. In severely affected sites, repeat applications should be made on 4 to 6 week intervals as long as soil temperatures are between 50°F and 70°F. Mapping of affected areas in the spring for spot-treatment in the fall can substantially reduce fungicide expenditures.

Fungicide and Formulation1
Amount of Formulation2
Application Interval3
Efficacy Rating
Resistance Risk
Fungicide and Formulation1

azoxystrobin
(Heritage, Strobe)
(Heritage TL)
(Heritage G)
(Strobe L)

Amount of Formulation2


0..2 to 0.4
2
2 to 4 lbs
0.38 to 0.77

Application Interval3


14 to 28
14 to 28
14 to 28
28

Efficacy Rating

+++



Resistance Risk

Low



Fungicide and Formulation1

azoxystrobin + acibenzolar-S-methyl (Heritage Action)*

Amount of Formulation2

0.2 to 0.4

Application Interval3

14 to 28

Efficacy Rating

+++

Resistance Risk

Fungicide and Formulation1

azoxystrobin + chlorothalonil (Renown)*

Amount of Formulation2

2.5
4.5

Application Interval3

14
14 to 21

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

azoxystrobin + difenoconazole (Briskway)*

Amount of Formulation2

0.3 to 0.725

Application Interval3

14 to 28

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

azoxystrobin + propiconazole (Headway)
ME
G

Amount of Formulation2


1.5 to 3
2 to 4 lbs

Application Interval3


14 to 28
14 to 28

Efficacy Rating

++++

Resistance Risk

Low

Fungicide and Formulation1

azoxystrobin + tebuconazole (Strobe T)*

Amount of Formulation2

0.75 to 1.5

Application Interval3

14 to 21

Efficacy Rating

++++

Resistance Risk

Fungicide and Formulation1

chlorothalonil + fluoxastrobin (Fame C)*
chlorothalonil + iprodione + thiophanate-methyl + tebuconazole (Enclave)*

Amount of Formulation2

3 to 5.9
3 to 4
7 to 8

Application Interval3

14 to 28
14 to 21
28

Efficacy Rating

+++
?

Resistance Risk

Low
Low

Fungicide and Formulation1

fluoxastrobin (Fame)
SC
G

Amount of Formulation2


0.28 to 0.36
2.3 to 4.6 lbs

Application Interval3


14 to 28
14 to 28

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

fluxapyroxad (Xzemplar)

Amount of Formulation2

0.21 to 0.26

Application Interval3

14 to 28

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

flutolanil (Prostar)

Amount of Formulation2

2.2

Application Interval3

30

Efficacy Rating

++++

Resistance Risk

Low

Fungicide and Formulation1

iprodione (26GT, Iprodione Pro, Ipro)*

Amount of Formulation2

4

Application Interval3

14 to 21

Efficacy Rating

++

Resistance Risk

Low

Fungicide and Formulation1

iprodione + thiophanate-methyl (26/36)*

Amount of Formulation2

2 to 4

Application Interval3

14 to 21

Efficacy Rating

++

Resistance Risk

Low

Fungicide and Formulation1

iprodione + trifloxystrobin (Interface)*

Amount of Formulation2

4

Application Interval3

14 to 21

Efficacy Rating

++

Resistance Risk

Low

Fungicide and Formulation1

metconazole (Tourney)

Amount of Formulation2

0.37

Application Interval3

14

Efficacy Rating

++++

Resistance Risk

Low

Fungicide and Formulation1

myclobutanil (Eagle, Myclobutanil)

Amount of Formulation2

2.4

Application Interval3

28 (fall)

Efficacy Rating

++

Resistance Risk

Low

Fungicide and Formulation1

penthiopyrad (Velista)

Amount of Formulation2

0.7

Application Interval3

14 to 28

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

propiconazole (Banner MAXX, Propiconazole)

Amount of Formulation2

3 to 4

Application Interval3

early fall

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

pyraclostrobin (Insignia)
WG
SC

Amount of Formulation2


0.5 to 0.9
0.4 to 0.7

Application Interval3


14 to 28
14 to 28

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

pyraclostrobin + boscalid (Honor)*

Amount of Formulation2

1.1

Application Interval3

14 to 28

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

pyraclostrobin + fluxapyroxad (Lexicon Intrinsic)

Amount of Formulation2

0.34 to 0.47

Application Interval3

14 to 28

Efficacy Rating

++++

Resistance Risk

Low

Fungicide and Formulation1

pyraclostrobin + triticonazole (Pillar G)

Amount of Formulation2

3 lbs

Application Interval3

14 to 28

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

tebuconazole
(Torque)*
(Mirage)*
(Tebuconazole)*

Amount of Formulation2


0.6 to 1.1
1 to 2
0.6

Application Interval3


21
28
28

Efficacy Rating

++++


Resistance Risk

Low


Fungicide and Formulation1

triadimefon (Bayleton)

Amount of Formulation2

1 to 2

Application Interval3

fall and spring

Efficacy Rating

+++

Resistance Risk

Low

Fungicide and Formulation1

triticonazole
(Trinity)
(Triton)

Amount of Formulation2


1 to 2
0.15 to 0.3

Application Interval3


14 to 28
14 to 28

Efficacy Rating

++++

Resistance Risk

Low

Fungicide and Formulation1

triticonazole + chlorothalonil (Reserve)*

Amount of Formulation2

3.2 to 5.4

Application Interval3

14 to 28

Efficacy Rating

++++

Resistance Risk

Low

1 Other trade names with the same active ingredients are labeled for use on turfgrasses and can be used according to label directions.
2 Apply fungicides in 2 to 5 gallons of water per 1,000 square feet according to label directions. Use lower rates for preventive and higher rates for curative applications.
3 Use shorter intervals when conditions are very favorable for disease.
* Products marked with an asterisk are not labeled for home lawn use.

Efficacy Rating
++++ = excellent control when conditions are highly favorable for disease development
+++ = good control when disease pressure is high, excellent control when disease pressure is moderate
++ = good control when disease pressure is moderate, excellent control when disease pressure is low
+ = good control when disease pressure is low
? = not rated due to insufficient data

Resistance Risk
Low = Rotate to different chemical class after 3-4 applications; tank mixing not necessary
Medium = Rotate to different chemical class after 1-2 applications; tank-mixing with low or medium risk product recommended
High = Rotate to different chemical class after EVERY application; tank-mix with low or medium risk product for EVERY application
? = not rated due to insufficient data

Presentations

Publications

Species Data

Host species

bermudagrass, centipedegrass,seashore paspalum, St. Augustinegrass, zoysiagrass

centipede11 ltc
centipede11 ltc
centipede11 ltc
centipede2 ltc
centipede2 ltc
centipede2 ltc
centipede3 ltc
centipede3 ltc
centipede3 ltc
centipede4 ltc
centipede4 ltc
centipede4 ltc
centipede6 ltc
centipede6 ltc
centipede6 ltc
centipede7 ltc
centipede7 ltc
centipede7 ltc
centipede9 ltc
centipede9 ltc
centipede9 ltc
centipede ltc
centipede ltc
centipede ltc
large patchbermuda1 ltc
large patchbermuda1 ltc
large patchbermuda1 ltc
large patchbermuda3 ltc
large patchbermuda3 ltc
large patchbermuda3 ltc
large patchbermuda4 ltc
large patchbermuda4 ltc
large patchbermuda4 ltc
large patchbermuda ltc
large patchbermuda ltc
large patchbermuda ltc
large patchcentipede11 ltc
large patchcentipede11 ltc
large patchcentipede11 ltc
large patchcentipede3 ltc
large patchcentipede3 ltc
large patchcentipede3 ltc
large patchcentipede8 ltc
large patchcentipede8 ltc
large patchcentipede8 ltc
large patchcentipede9 ltc
large patchcentipede9 ltc
large patchcentipede9 ltc
large patchcentipede ltc
large patchcentipede ltc
large patchcentipede ltc
large patchst aug ltc
large patchst aug ltc
large patchst aug ltc
large patchzoysia1 ltc
large patchzoysia1 ltc
large patchzoysia1 ltc
large patchzoysia2 ltc
large patchzoysia2 ltc
large patchzoysia2 ltc
large patchzoysia ltc
large patchzoysia ltc
large patchzoysia ltc
sheath lesionstaug3 ltc
sheath lesionstaug3 ltc
sheath lesionstaug3 ltc
sheath lesionstaug4 ltc
sheath lesionstaug4 ltc
sheath lesionstaug4 ltc
sheath lesionstaug6 ltc
sheath lesionstaug6 ltc
sheath lesionstaug6 ltc
Months with symptoms

August to May

Stand symptoms

patches (1 foot to greater than 3 feet)

centipede11 ltc
centipede11 ltc
centipede11 ltc
centipede2 ltc
centipede2 ltc
centipede2 ltc
centipede4 ltc
centipede4 ltc
centipede4 ltc
centipede6 ltc
centipede6 ltc
centipede6 ltc
centipede7 ltc
centipede7 ltc
centipede7 ltc
centipede9 ltc
centipede9 ltc
centipede9 ltc
centipede ltc
centipede ltc
centipede ltc
large patchbermuda1 ltc
large patchbermuda1 ltc
large patchbermuda1 ltc
large patchbermuda3 ltc
large patchbermuda3 ltc
large patchbermuda3 ltc
large patchbermuda4 ltc
large patchbermuda4 ltc
large patchbermuda4 ltc
large patchbermuda ltc
large patchbermuda ltc
large patchbermuda ltc
large patchcentipede11 ltc
large patchcentipede11 ltc
large patchcentipede11 ltc
large patchcentipede3 ltc
large patchcentipede3 ltc
large patchcentipede3 ltc
large patchcentipede8 ltc
large patchcentipede8 ltc
large patchcentipede8 ltc
large patchcentipede9 ltc
large patchcentipede9 ltc
large patchcentipede9 ltc
large patchcentipede ltc
large patchcentipede ltc
large patchcentipede ltc
large patchst aug ltc
large patchst aug ltc
large patchst aug ltc
large patchzoysia1 ltc
large patchzoysia1 ltc
large patchzoysia1 ltc
large patchzoysia2 ltc
large patchzoysia2 ltc
large patchzoysia2 ltc
large patchzoysia ltc
large patchzoysia ltc
large patchzoysia ltc
Foliar symptoms location/shape

lesions on leaf sheaths

sheath lesionstaug3 ltc
sheath lesionstaug3 ltc
sheath lesionstaug3 ltc
sheath lesionstaug4 ltc
sheath lesionstaug4 ltc
sheath lesionstaug4 ltc
sheath lesionstaug6 ltc
sheath lesionstaug6 ltc
sheath lesionstaug6 ltc
Foliar symptoms color

tan, yellow, orange, red

sheath lesionstaug3 ltc
sheath lesionstaug3 ltc
sheath lesionstaug3 ltc
sheath lesionstaug4 ltc
sheath lesionstaug4 ltc
sheath lesionstaug4 ltc
sheath lesionstaug6 ltc
sheath lesionstaug6 ltc
sheath lesionstaug6 ltc
Root/Crown symptoms

none

Fungal Signs

none