Phoma of Chickpea

Note Number: AG0452
Published: June 2008
Updated: August 2012

Phoma has the potential to be a serious disease of chickpea. Relatively few serious outbreaks have occurred, however, the disease is common in southern Australia. Careful paddock selection and use of fungicide seed dressings can minimise the impact of this disease.

What to look for

Seed-borne infection often results in black-brown discolouration of the root near where the seed is attached. Blackening may spread up the root and cause lesions at the base of the stem (Figures 1 & 2).

Initial above ground symptoms are small, dark tan coloured, irregular flecks on leaves, stems, and pods. The flecks on leaves enlarge to lesions and the surrounding tissue yellows. Within the lesions numerous pinhead-sized black fruiting bodies of the fungus develop. On the stem, similar but more elongated lesions form.

Black lesions may completely girdle the base of the stem and root where infection is severe (Figure 1). Pod lesions are sunken, with pale centres and dark margins, and may be covered by small black spots. The fungus may penetrate the pod and infect developing seeds. Badly affected plants may be totally defoliated when infected leaflets senesce and fall.

Fig 1. Characteristic collar and root rot caused by Phoma.	Fig 2. Stem lesions caused by Phoma infection.

Disease cycle

Phoma, caused by the fungus Phoma medicaginis var. pinodella can survive on infected seed, in soil and on crop residue from one season to the next. Infection can occur at any stage of plant growth provided conditions are favourable. Moisture is essential for infection to occur. During wet weather, the disease may spread further when spores of the fungus are carried by wind and rain splash onto neighbouring plants. Pod infection can occur when the fungus penetrates the pod wall and infects developing seeds late in the season.

Economic importance

The only serious outbreaks of this disease on chickpea in Australia have occurred in very wet years. However, it is usually a more damaging disease on field pea than chickpea.

Management

Before sowing

Use clean seed

The use of disease free seed and crop rotation will help prevent the establishment and build-up of this disease.

Crop Rotation

Where chickpeas have been badly infected, a two year break from host crops will minimise the disease risk. Crops which host phoma include field pea, chickpea, faba bean, lupin, lentil, vetch and legume pasture species. Cereal and oilseed crops will provide a good disease break.

Chemical control

Seed-borne disease infection can sometimes be controlled with fungicide seed dressings. No fungicides are known to manage this disease in crop.

Further references

Pulse Australia
DPI Information Notes
National Variety Trials
Victorian Winter Crop Summary
Winter Pulse Disorders: The Ute Guide
Seed Health Testing in Pulse Crops (AG1250)

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

Acknowledgements

This Information Note was originally written by Helen Richardson and Kristy Hobson. It was reviewed by Frank Henry and Helen Richardson, Farm Services Victoria - BioSciences Research, March 2010 and August 2012. Financial support by the GRDC is gratefully acknowledged.