Powdery mildew of parsley
Powdery mildew of parsley can be caused by the fungi Erysiphe heraclei and Leveillula lanuginose. Neither powdery mildew has been reported on parsley in Australia.
Symptoms of powdery mildew
Erysiphe heraclei produces a white powdery growth on the upper surface of leaves (Figure 1) which leads to yellowing, crinkling and early death of older leaves. It occurs on stems and flower stalks. Crop losses of up to 50 per cent have been reported in the USA, and it is considered a significant pathogen in Europe.
Leveillula lanuginose produces white powdery growth on both the upper and lower surface of leaves and on stems. Angular yellow blotches develop on the upper surface of leaves. It is sporadic and of little economic importance.
Both fungi have a wide host range in the Apiaceae, but E. heraclei is known to include many host-specific races. The carrot type of E. heraclei was detected in Australia during 2007, but it did not infect parsley or celery and only a restricted infection was observed on parsnip.
Spread of powdery mildew
The fungus E. heraclei is thought to be seedborne. Hot dry conditions promote the disease while wet weather and overhead irrigation retard it. Disease development can be rapid during late summer and early autumn. Spores produced on the leaf surfaces are rapidly spread within a crop by air currents. The fungus probably survives season to season on volunteer plants, sequential host crops and possibly by ‘survival’ spores in crop debris.
Controlling powdery mildew
- Maintain good hygiene practices, such as weed control, avoiding sequential plantings and carry over of crop debris.
- Avoid shady conditions as sunlight is detrimental to spore survival.
- Use overhead irrigation.
Current situation in Victoria
Powdery mildew disease in parsley has not been reported in Australia to date. If you suspect you have powdery mildew symptoms on parsley plants, please report to the Exotic Plant Pest Hotline.
Distribution of powdery mildew
E. heraclei is present on parsley in the USA, Brazil, Europe and Asia. L.lanuginose has been reported on parsley in Greece and Italy.
- Koike ST, Gladders P, Paulus AO (2007), Vegetable Diseases: A Colour Handbook, Mason Publishing, 448p.
- Raid R, Miller C, Pernezny K (2007) First Report of Powdery Mildew of Parsley Caused by Erysiphe heraclei in Florida
- Rosa DD, Ohto CT, Basseto MA, Souza NL de, Furtado EL (2008), Brazil, a new location for powdery mildew on parsley and fenchel plants, Blackwell Publishing, Oxford, UK, Plant Pathology, 2008, Vol. 57, No. 2, pp.373
- Watson A (2011), Erysiphe heracleid, Pathogen of the month – 2011
Figure 1 courtesy of AHDB