Pests, diseases and weeds
Leeks suffer few problems with pests, although onion seedling maggot, two-spotted mite and caterpillars can be a problem. If present in large numbers, thrips and snails can damage young seedlings. Root-knot nematode is not a problem.
Fusarium basal rot (Fusarium spp.) can be a problem with continuous cropping. Rotation with other crops is the only way to minimise the impact of this disease.
Bacterial soft rot is sometimes a problem in cooler months, especially in leaves and shanks below ground. There are often physical causes for this condition, such as plant damage from hot weather or mechanical operations, allowing the bacteria entry points to the stem. The seed-borne disease bacterial blight, caused by the organism Pseudomonas syringae pv. porri, has been identified in South Australia and Victoria.
Good control of weeds by hand is essential, because of the lengthy period from planting to harvesting.
The registration and availability of chemicals for pest, disease and weed control changes regularly. Consult a trained and experienced horticultural agronomist or the Australian Pesticides and Veterinary Medicines Authority (APVMA) website for chemicals which are currently registered or have a permit for use on this crop. The information on the label or permit for a chemical must be followed, including the directions for use, critical use comments, withholding period and maximum residue limit. Quality assurance (QA) schemes for horticultural crop production require producers to have current information on chemical registrations readily available.