euteiches Dreshler Classification Disease Common Name (b). Oospores thein of tip a bean root (c). Fig. 1. Key Contacts: Andrew Watson, NSW Department of Primary Industries, of Department 0269512647 NSW KeyWatson, Andrew Contacts: DJ(1982)Hagedorn Pfender & WF Virginia Experiment Station. Agricultural Genus the of (1961) AScott monograph WW Reading: Further by species of isolate from infected plant material, often overtaken to machine harvest. have variabilityin pod maturation reducing the ability or irrigation isinadequate. Crops that do survivemay root activity if hot weather occurs and where rainfall plant death. Plants can and wiltdie due to reduced stem reducing plant vigour and but yield not causing disease causes browningof the roots and the lower cause of disease itson own. In beans and peas the soilborne disease complex but it can be the prime Aphanomyces Impact: different Australianisolates. comparisons have not been undertaken with Broad cross infection studies with genetic bean roots withoutsymptoms on the hypocotyl. euteiches infecting peas. The pea isolateknown as from beans ( different forma specialis(f.sp.) with the type isolated Aphanomyces euteiches Host Range: in the cellwall. soilfor many years or from hyphae in infected plant material. The hyphaehave no septa and contain cellulose irrigation whichis also required for infection. Zoospores can either developfrom oospores that survivein the lucerne. The fungus produces motile zoospores that are produced during periods of high rainfall or excessive in some cases the hypocotyl. The pathogen is found commonly affecting peas, beans, faba beans, cloverand Aphanomyces euteiches a

Symptoms on beanSymptoms plants causing brownroots Zoospores andstem(a). lowerencysting at the end of the sporangia

:

f.sp. A. euteiches

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: iscommonly assumed to be part of a pisi

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Aphanomyces euteiches K: Chromista, D: Oomycota, C: , O: , Aphanomyces root rot of legumes. F: Leptolegniaceae Pathogenof the month

may cause some infection on Aphanomyces

and

has been shown to exist as isa f.sp. b

Pythium

fungal fungal pathogen found in many areas of Australia causing browningof roots and

phaseolus) Phytopathology

is difficult isdifficult to .

A.

not not Aphanomyces. Aphanomyces. Technical Bulletin

72, 306

- Australia. dressing on beans but isunlikely to be inavailable product has also shown to be effective as a seed cochlioides hymexazolsuccessfully controls A years in soil. Metalaxyldoes not control often difficult as the fungus can survivefor many way to reduce the impact from this disease, but this is Avoidance of fields with severe infections is the only limited if any resistant varieties across the host range. No chemical control methods are available. There are Control: infected plant material. Oospores are also characteristic and numerous in cultures or infected roots are placedwater. in opening. This process can easilybe observed if shape, congregate and encyst at the sporangial zoospores are then ejected, form into a spherical protoplasmic contents of the sporangia. The zoospores that are produced by segmentation of the Aphanomyces KeyDistinguishing Features: 310. phanomyces

c

on sugar beet in the United States. The –

howevera seed dressing containing species produce characteristic

December

151

Aphanomyces

2011