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Parsnip Canker



P_psnipcnkr

Parsnip Canker

Usually appear in

Autumn to Winter


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Caused By:-     Various Fungi

Description

Parsnip Canker can be a serious disease of parsnips especially in wet soils. It is caused mainly by the fungus Intersonilia pastinaceae, though other fungi, like Phoma and Mycocentrospora, can cause this disease. It causes the storage root to darken starting from the crown, shoulder or sides which then crack and eventually rot. This rotting may be due to secondary invasion from bacteria or fungi. Infected areas vary in size from a few millimetres to several centimetres.
It is also responsible for leaf-spot disease where small pale green or water soaked spots which may or may not have a paler halo. Spores that are produced on leaves fall to the ground where they come in touch with the roots.
The fungi survive in the soil and can build up to damaging levels if too parsnip are grown in the same place year after year. The seed may also be a source of the infection.
Carrot-fly and hoeing injury can let the disease into the roots.
See these other Cankers Apple and Pear, Bacterial, Bleeding, Canker, Cytospora, European, Horse Chestnut Bleeding, Mulberry, Pear and Apple, Phomopsis, Poplar Bacterial, Rose Stem and Dieback, Willow Black.


Control

Prompt removal and disposal by burning of debris from infected source is essential.
Keeping carrot fly away by covering the roots with fleece or insect-proof mesh in early summer when the Carrot Root fly is most active should reduce damage.
Crop rotation is essential in preventing build up of this fungus.
Ridging up Ridge up just before foliage meets within rows should help keep the fungus from the roots and help prevent attack.
Acidic pH also makes the disease more likely and more severe. Ensuring good drainage with adequate composted materials and a soil ph above 6.5 will help. If there has been a history of this disease early harvesting and watering the soil with a soil sterilant will help.
Early sowings and larger roots are worst affected. Sowing in late April, May and even June will help reduce attack.
Once attacked there is nothing that can be done, but spraying the leaf stage with a systemic insecticide will help prevent attack.
There are resistant varieties that can be planted.



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