Common blight of beans
Note Number: AG0557
Published: December 1999
Updated: September 2010
Xanthomonas campestris pv. phaseoli
Common blight, caused by a bacterium which infects foliage, pods and seed is very destructive and can cause major losses in yield.
Symptoms initially appear on leaves as water soaked, often angular shaped spots and gradually grow to form large-brown spots of dead tissue, often surrounded by a very narrow zone of yellow tissue. Spots can form at the margins and interveinal regions. In severe infections, the plant appears burnt and dead leaves remain attached.
Spots on pods are generally circular, slightly sunken, water-soaked and dark green in colour. As spots age they turn dark red-brown in colour and under extremely humid conditions are covered with bacterial ooze.
Symptoms of common blight appear similar to halo blight, but halo blight has leaf spots with large, pale yellow margins.
Bacteria enter plants through wounds or natural openings. It takes 10-14 days from initial infection for new bacteria to be released.
The bacterium can survive either inside the seed or on the seed surface. Tolerant varieties may harbour the bacterium. It over winters on infected plant debris, especially on residues near the soil surface. The bacterium can also survive on the surface of volunteer beans, weeds and intercropped plants without showing any symptoms.
Contaminated seed is the major means of dispersal of the bacterium. It is also spread by plant to plant contact, especially when wet and by water splash from rain or overhead irrigation. It can be transported in soil, irrigation water, by insects, animals and people.
Development of the disease is favoured by warm-humid weather, with or without rain and temperatures of 28-32 °C.
French and mung beans.
- Use disease-free seed.
- Plant tolerant or resistant cultivars.
- Use a crop rotation of two or more years between bean crops.
- Eliminate alternate hosts such as volunteer beans and weeds.
- Use a registered bactericide spray if weather conditions favor disease development.
- Avoid overhead irrigation.
Persley, D., Cooke, T. and House, S. (2010). Diseases of vegetable crops in Australia. CSIRO Publishing, 292p.
Koike, S.T., Gladders, P. and Paulus, A.O. (2007). Vegetable diseases, a colour handbook. Mason Publishing, 448p.
Howard, F. S., James, R. S., Robert, H., and Robert, L. F. (2005) Compendium of Beans diseases. APS Publishing, 120p.
Contact/services available from DEPI
For effective pest and disease control, correct diagnosis is essential. Phone Crop Health Services on (03) 9032 7515 or fax (03) 9032 7604.
For further information on registered chemicals, phone the DEPI Customer Service Centre on 136 186.
This Agriculture Note was developed by Elizabeth Minchinton, Knoxfield in December 1999.
It was reviewed by Elizabeth Minchinton, BioSciences Research in September 2010.
Published and Authorised by:
Department of Environment and Primary Industries
1 Spring Street
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