Bacterial Blight Peas
Pseudomonas syringae pv. pisi
Pseudomonas syringae pv. syringae
A bacterial disease of Peas. Plants from infected seed develop water soaked spots on the stems near ground level that become purplish brown with age. Stems may be thin and shrivelled. Bacteria from these lesion infect leaves of other plants. The lesion tends to fan out from the base of the leaflet or may be on the edges. Initially they have a water soaked appearance and change to yellow then brown and then the tissue dies and becomes grey brown and papery. On pods the lesion usually appears on the edges and as dark green water soaked areas that that soon become dark brown patches. Infected young pods often shrivel. A cream coloured, slimy substance is sometimes produced from the lesions in wet conditions. Small black seed remnants or shrivelled seed may occur depending on the time of infection.
Species Affected:Peas, Sweet Pea and some other Pisum species.
Biology:Infects plants through wounds and stomata.
Frost, sand blasting and wind damage may lead to increased infections.
Favoured by cool to warm, wet weather.
Carried on seed.
May be spread by workers or machinery in wet crops and by harvesting and grain handling and cleaning equipment.
Inspections need to occur before flowering and continue through grain fill to find the disease.
Life Cycle:Origin and History:
Can cause total crop loss with early infections followed by wet windy weather.
It is usually only a severe problem where the crop has been physically damaged.
Management and Control:Use healthy seed. Harvest seed early and from the cleanest part of the paddock.
Test seed for the disease (Current tests only detect the pv. pisi form)
Clean seed cleaning equipment between seed lots.
Reduce Pea stubble by grazing, burying, burning or chopping.
Rotate to resistant crops.
Don't plant Peas in infected areas for 3 years.
Delay planting in risky situations.
Control volunteer Pea plants and weeds.
Avoid frost prone paddocks.
Use tram lines to minimise crop damage and avoid paddocks where sandblasting may occur.
Don't work in wet crops.
Related and Similar Species:References:
Eric Armstrong, NSW Agriculture.
Trevor Bretag, DPI Victoria.
Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.