Septoria Blotch of Field Pea
Note Number: AG1164
Published: May 2008
Updated: August 2012
Septoria blotch of field peas is usually a minor disease occurring sporadically in Victoria and South Australia but has caused major crop losses in NSW. The disease is often seen on senescing plants late in the growing season. The disease can be prevented by stubble management and crop rotation.
What to look for
The disease is mainly found on the lower, senescing parts of the plant and pods. Diseased areas on leaves are of indefinite size and shape and are yellow then straw coloured to light brown (see Figure 1), often with a lighter centre and a pale yellow halo on the margin. Several such blotches may join together to cover the entire leaf. Within the lesions, pin-point sized black fruiting bodies of the fungus may be seen (see Figure 2). Diseased tissues may dry off prematurely.
Septoria blotch is caused by the fungus Septoria pisi. The fungus survives from one season to the next on infected pea trash and seed. Spores of the fungus are carried by wind from infected trash, into the new crop. Infection is found on the lower foliage where the humidity is high following rain or heavy dews. The disease is favoured by warm temperatures (21 to 27°C) and extended periods of high humidity. Secondary spread occurs during the growing season. Rain splash assists in spreading the disease within a crop. Whilst seed transmission can occur it is unlikely to be important.
This disease occurs sporadically and seldom causes significant yield losses. However, losses of up to 40 per cent have been reported in some susceptible pea varieties.
Septoria can be managed by using an integrated approach that encompasses crop rotation, stubble management and fungicides.
The septoria blotch fungus survives in soil and on old pea trash. It is only safe to re-crop an area with peas after all pea debris has decomposed. Destroying pea stubble by grazing, burning and cultivation will help in reducing the pea debris more quickly. This also minimises the amount of inoculum available to infect new crops.
No foliar or seed applied fungicides are registered for use on septoria in field peas in Victoria.
Contact/Services available from DPI
DPI Field Crops Pathology, Grains Innovation Park, 110 Natimuk Rd, Horsham 3400. Tel (03) 5362 2111, or the DPI Customer Service Centre 136 186
This Information Note was originally written by Trevor Bretag.
It was reviewed by Helen Richardson and Frank Henry, BioSciences Research - Farm Services Victoria, March 2010.
Financial support by the GRDC is gratefully acknowledged.