Serious New Patch Diseases of Warm-Season Turf Grasses

Dr Percy WongPlant Breeding Institute

University of Sydney

Overview

� Patch diseases of couch, buffalo and kikuyu

� ERI fungal diseases

� Five new serious diseases in the last 15 years� Fairway patch� Summer decline� Adelaide patch� Wongoonoo patch� Deniliquin patch

ERI Fungal Diseases

� ERI fungi = Ectotrophic Root-Infecting fungi

Diseased water-conducting tissues of roots

Classic ERI Fungal Diseases

Disease Pathogen Hosts

Take-all patch Gaeumannomyces graminis var. avenae Creeping bentgass , couch

Root decline of warm season turfgrasses

Gaeumannomyces graminis var. graminis Couch, warm season turfgrasses

Summer patch Magnaporthiopsis poae (Magnaporthe poae) Kentucky bluegrass, Poa annua

Necrotic ring spot Ophiosphaerella korrae (Leptosphaeriakorrae)

Kentucky bluegrass, Poa annua

Dead spot Ophiosphaerella agrostidis Creeping bentgrass

Spring dead patchOphiosphaerella narmariOphiosphaerella korrae Couch, buffalo, kikuyu

New ERI Fungal Diseases in Australia

Disease Pathogen Hosts

Fairway patch Phialocephala bamuru (BF1) Couch, kikuyu

Summer decline Wongia griffinii (Magnaporthe griffinii) Couch, hybrid couch, kikuyu

Adelaide patch Wongia garrettii (Magnaporthe garrettii) Couch, buffalo

Wongoonoo patch Gaeumannomyces wongoonoo Buffalo, couch

Deniliquin patch Budhanggurabania cynodonticola Couch

Patch disease on couch

Diseased roots

Steps in diagnosis

� Examine leaves, stems and roots under dissecting microscope

� Examine washed roots and stolons under dissecting microscope

� Examine root squash on slide under compound microscope for typical hyphae or spores

� Plate out infected roots on agar to isolate the pathogen or pathogens

Plating out infected roots and stems

Pathogen growing out of a diseased root

Isolation of fungi from diseased roots

Isolation of pathogen from diseased roots

Pure culture of the pathogen

How do we prove that a fungus is

the cause of the disease?

Koch’s Postulates

� The pathogen should always be associated with the disease

� The pathogen should be isolated from the diseased roots into pure culture

� If a healthy host is inoculated with the pure culture, the same disease symptoms should develop

� The same pathogen should be re-isolated from the diseased roots

Glasshouse test for pathogenicity

Disease symptom expression

Disease symptom expression

Re-isolation of the pathogen

Pure culture of the pathogen

Fairway Patch

Fairway patch on golf fairway

� Pathogen photo

Fairway patch on green surrounds

� photo

Bonnie Doon green surrounds and fairway

18th green surrounds at Royal Sydney

Fairway patch at The Australian Golf Club

Fairway patch at Avondale Golf Club

Fairway patch at New South Wales Golf Club

BF1 on two fairways at NSWGC

Fairway Patch at Kingston Heath Golf Club

Golf Clubs with Fairway PatchNSW�Bonnie Doon�New South Wales�Royal Sydney�The Australian (2015)�St Michael’s�Eastlake�Pymble�Avondale�Elanora�Ryde – Parramatta�Twin Creeks (near Penrith)�Pacific Dunes (near Newcastle)

QLD�The Grand�Pacific Harbour (2015)

WA�Gosnells (2015)�Mt Lawley (2015)�Collier Park (1016)

VIC�Kingston Heath (2015)

�SA ??

Affected turf species and cultivars

� Couch

� Wintergreen

� Windsor Green

� Santa Ana

� Legend

� Greenlees Park

� Common couch

� Kikuyu

Fairway patch in kikuyu

� photo

Fairway patch in kikuyu

� photo

Identity of the pathogen (BF1)

� BF1 has not produced any spores for easy identification

� Not a known turf pathogen like Rhizoctonia, Gaemannomyces orOphiosphaerella

� DNA work has shown that it is a new fungal species, Phialocephala bamuru

How does the pathogen spread?

How does the pathogen spread?

� Infected turf – divots, corings, sprigs, etc.

� Golf shoes, golf carts, other vehicles, wind

� Maintenance equipment – mowers, corers, earth-moving equipment

� Predictions

� It is only a matter of time before most golf clubs will be infected

� Turf farms could be infected if debris is brought back to the farms

Research on control of fairway patch

� Replicated field trials on infected golf fairways

� Strategic fungicide applications

� Biological control agents

� Organic and other amendments

� Cultural control

� Integrated control to manage disease

Field trial at Bonnie Doon Golf Club

Summer Decline

Summer Decline

� Patch disease of couch, hybrid couch, South African couch and kikuyu

� Found in Qld, NSW, VIC, SA and WA

� Caused by Wongia griffinii (Magnaporthe griffinii)

� Serious decline disease

� No satisfactory chemical control

Summer decline at Killara Golf Club, NSW

Summer Decline at Carbrook Golf Club, QLD

Diseased root systems

Diseased roots and stolons

Vascular discolouration of roots

Sexual stage of Wongia griffinii

Spores of Wongia griffinii

Adelaide Patch

Adelaide Patch

� First found in Adelaide (Colonel Light Gardens Bowling Club) on Greenlees Park couch

� Also occurs on buffalo grass in NSW

� Caused by Wongia garrettii (Magnaporthe garrettii)

� Devastating patch disease but is relatively uncommon

� No satisfactory chemical control

Adelaide Patch on bowling green

Sexual stage of Wongia garrettii

Spores of Wongia garrettii

Summer Patch

Summer Patch on the White House lawn

Summer Patch

� Caused by Magnaporthiopsis poae Landschoot & Jackson (1987)

� Disease of cool-season grasses

� Not found in Australia

� Preventative control possible with chemicals

Spores of Magnaporthiopsis poae

Wongoonoo Patch

Wongoonoo Patch in Buffalo

Take-all Patch in Tifdwarf Couch

Take-all PatchGaeumannomyces graminis var. avenae

Wongoonoo Patch

� Caused by a relative of the take-all fungus named Gaeumannomyces wongoonoo (Wong 2002)

� A patch disease similar to take-all patch in couch

� Occurs mainly on buffalo grass but has now been found in couch

� Chemicals that control take-all patch may be effective

Deniliquin Patch

Deniliquin Patch on Deniliquin Golf Club

Deniliquin Patch on a bowling green

Deniliquin Patch

� A devastating patch disease on couch

� Caused by a new genus and species of fungus� Budhanggurabania cynodonticola (Wong et al. 2015)

� It may be part of a disease complex

� Has not been controlled by chemicals

Budhanggurabania cynodonticola

Accurate diagnosis

� To manage turf diseases, an accurate diagnosis is essential

� Many disease symptoms look alike

� We often use American information on diseases but symptoms in the US may be different to those in Australia

� We also have diseases in Australia that do not occur in the US and vice versa

Disease Management

� For some of these intractable diseases, a long-term disease management program is required

� We may not be able to eradicate the pathogen

� Management would consist of using chemicals, biological control agents and cultural methods

� The long-term solution is to identify resistant cultivars

Management strategies

� Apply chemicals before couch comes out of dormancy

� Choose chemicals that are compatible with biological agents

� Apply biological control agents or organic amendments regularlye.g. composts or Trichoderma products

� Remove thatch to reduce the amount of the pathogen

� Fertilise judiciously to keep turf root systems growing actively

� If possible, mow at a height that does not stress the turf

Conclusions

� For ERI fungal diseases, diseased roots should be plated out onto agar to isolate the pathogens for an accurate diagnosis

� Accurate diagnosis allows chemicals to be used rationally or else money is wasted

� Build up local knowledge and not depend solely on information from the United States or the internet

� We should train more professional turf pathologists in Australia so that more research can be done locally