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White Tip

Phytopthora porri




Leeks. Can also be found on onions and other Allium spp


Can be first seen in late summer (end July) but more readily found in late autumn. The first symptoms are yellowing lesions at the leaf tips which become dry, bleached and white. As the lesions develop they can coalesce causing dieback on large areas of leaf tissue. On close inspection water soaked regions can be observed between the lesion and healthy tissue.


White tip survives in the soil as oospores for periods of 3 years or more. These germinate to form sporangia (spore containing bodies) which release spores to infect host plants. Established lesions produce further oospores to distribute the disease more widely.

Favourable Factors

Develops in cool, humid, wet conditions.


An important disease of leeks in Western Europe and the UK. Has become more of a problem as leek production increases and effective fungicide options decrease.


Identification and Management of onion and leek diseases

Find out more information on the key disease threats to your onion and leek crop. For each disease you will find out the importance of the disease in terms of potential yield penalty, how to identify the disease in its early stages and our advice on the best control strategies.

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